Servlet 详细教程 + 案例

发布于:2023-01-22 ⋅ 阅读:(19) ⋅ 点赞:(0) ⋅ 评论:(0)

Servlet 方法介绍

  • init():初始化方法
    • 调用时机:默认情况下,servlet 被第一次访问时,调用
      • 可通过 loadOnStartup 修改
    • 调用次数:1次
  • service():提供服务
    • 调用时机:每一次Servlet被访问时,调用
    • 调用次数:多次
  • destory():销毁方法
    • 调用时机:内存释放或者服务器关闭的时候,Servlet对象会被销毁,调用
    • 调用次数:1次
  • getServletConfig():获取 ServletConfig 对象
  • getServletInfo():获取 Servlet 信息(author、version、copyright)

Servlet urlPattern 配置

  • 一个 Servlet 可以配置多个 urlPattern @WebServlet(urlPatterns = {"/demo3", "/demo4"})
  • urlPattern 配置规则
    • 精确匹配
      • 配置路径:@WebServlet("/demo3")
      • 访问路径:localhost:8080/web-demo/demo3
    • 目录匹配
      • 配置路径:@WebServlet("/user/*")
      • 访问路径:localhost:8080/web-demo/user/aaalocalhost:8080/web-demo/user/bbb
    • 扩展名匹配
      • 配置路径:@WebServlet("*.do")
      • 访问路径:localhost:8080/web-demo/aaa.dolocalhost:8080/web-demo/bbb.do
    • 任意匹配
      • 配置路径:@WebServlet("/")@WebServlet("/*")
      • 访问路径:localhost:8080/web-demo/hehelocalhost:8080/web-demo/haha

//* 的区别

  • 当我们的项目中的Servlet配置了 /,会覆盖掉 tomcat 中的 DefaultServlet,当其他的 url-pattern 都匹配不上时都会走这个Servlet
  • 当我们的项目中配置了 /*,意味着匹配任意访问路径

优先级:精确路径 > 目录路径 > 扩展名路径 > /* > /

IDEA 模板创建 Servlet

 

#if (${PACKAGE_NAME} && ${PACKAGE_NAME} != "")package ${PACKAGE_NAME};#end
#parse("File Header.java")

#if ($JAVAEE_TYPE == "jakarta")
import jakarta.servlet.*;
import jakarta.servlet.http.*;
import jakarta.servlet.annotation.*;
#else
import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
#end
import java.io.IOException;

@WebServlet("/${Entity_Name}")
public class ${Class_Name} extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

中文乱码问题

POST 乱码

  • getReader() 默认编码是 iso-8859-1
  • 设置字符输入流的编码为 UTF-8request.setCharacterEncoding("UTF-8");

GET 乱码

 

 

URL 编码

  • 将字符串按照编码方式转为二进制
  • 每个字节转为2个16进制并在前边加上% 

 

 

URL编解码Demo 

package com.ruochen.web;

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;

public class URLDemo {
    public static void main(String[] args) throws UnsupportedEncodingException {
        String username = "张三";

        // 1. URL 编码
        String encode = URLEncoder.encode(username, "utf-8");
        System.out.println(encode);

        // 2. URL 解码
        String decode = URLDecoder.decode(encode, "ISO-8859-1");
        System.out.println(decode);
    }
}

 

  %E5%BC%A0%E4%B8%89
  å¼ ä¸

tomcat ISO-8859-1 接码我们无法改变,但是我们可以发现 URL 编码数据和接收打的数据字节是一样的(二进制数据 10101xxxx),这就为我们提供了一种思路:我们可以将乱码的数据转换为字节数据(二进制数据),再将二进制字节数据转换为字符串,demo 如下


 

package com.ruochen.web;

import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.net.URLEncoder;

public class URLDemo {
    public static void main(String[] args) throws UnsupportedEncodingException {
        String username = "张三";

        // 1. URL 编码
        String encode = URLEncoder.encode(username, "utf-8");
        System.out.println(encode);

        // 2. URL 解码
        String decode = URLDecoder.decode(encode, "ISO-8859-1");
        System.out.println(decode);

        // 3. 转换为字节数据,编码
        byte[] bytes = decode.getBytes("ISO-8859-1");
        for (byte b : bytes) {
            System.out.print(b + " ");
        }
        System.out.println();

        // 4. 将字节数组转换为字符串,解码
        String string = new String(bytes, "utf-8");
        System.out.println(string);
    }
}
  %E5%BC%A0%E4%B8%89
  å¼ ä¸
  -27 -68 -96 -28 -72 -119 
  张三

servlet demo

@WebServlet("/req1")
public class RequestDemo1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 解决post乱码 getReader() 默认编码是 iso-8859-1
        request.setCharacterEncoding("UTF-8");  // 设置字符输入流的编码

        String username = request.getParameter("username");
        System.out.println("解决乱码前:" + username);

        // GET 获取参数的方式:getQueryString()
        // 乱码原因:tomcat 进行URL解码,默认的字符集ISO-8859-1
        // 1. 先对乱码进行编码,转为字节数组
        // byte[] bytes = username.getBytes(StandardCharsets.ISO_8859_1);
        // 2. 字节数组解码
        // username = new String(bytes, StandardCharsets.UTF_8);
        username = new String(username.getBytes(StandardCharsets.ISO_8859_1), StandardCharsets.UTF_8);

        System.out.println("解决乱码后:" + username);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

 Tomcat 8 之后,已将GET请求乱码问题解决,设置默认的解码方式为 UTF-8

路径问题

  • 明确路径谁使用?
    • 浏览器使用:需要加虚拟目录(项目访问路径)
    • 服务端使用:不需要加虚拟目录
  • 练习
    • <a href = "路径">:加虚拟目录
    • <form action="路径">:加虚拟目录
    • req.getRequestDispatcher("路径"):不需要加虚拟目录
    • resp.sendRedirect("路径"):需要加虚拟目录


 

 

 

Response 响应字符数据

  • 使用 Response 对象获取字符输出流:PrintWriter writer = resp.getWriter();
  • 写数据:write.write("aaa");
  • 可通过设置 header 指定类型:resp.setHeader("content-type", "text/html");
  • 流不需要关闭,resp 对象销毁的时候会自动关闭
  • 中文乱码,设置流的编码:resp.setContentType("text/html;charset=utf-8");

Response 响应字节数据

  • 通过 Response 对象获取字节输出流:ServletOutputStream outputStream = resp.getOutputStream();
  • 写数据:outputStream.write(字节数据);
  • 案例
package com.ruochen.web;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.FileInputStream;
import java.io.IOException;

@WebServlet("/resp1")
public class ResponseDemo1 extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // 1. 读取文件
        FileInputStream fis = new FileInputStream("C:\\Users\\ruochen\\Desktop\\离雨.jpg");

        // 2. 获取 response 字节输出流
        ServletOutputStream os = response.getOutputStream();

        // 3. 完成流的 copy
        byte[] buff = new byte[1024];
        int len = 0;
        while((len = fis.read(buff)) != -1) {
            os.write(buff, 0, len);
        }
        fis.close();
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}
  • 我们可以使用 commons-io 工具类简化上述操作
  • 导入坐标:pom.xml
            <dependency>
                <groupId>commons-io</groupId>
                <artifactId>commons-io</artifactId>
                <version>2.6</version>
            </dependency>

    上述循环遍历代码可简化为如下

IOUtils.copy(fis, os);

 

用户登录案例

准备工作

  • login.html 放到 webapp 目录下
<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>login</title>
    <link href="css/login.css" rel="stylesheet">
</head>

<body>
<div id="loginDiv">
    <form action="/web-demo/loginServlet" method="post" id="form">
        <h1 id="loginMsg">LOGIN IN</h1>
        <p>Username:<input id="username" name="username" type="text"></p>

        <p>Password:<input id="password" name="password" type="password"></p>

        <div id="subDiv">
            <input type="submit" class="button" value="login up">
            <input type="reset" class="button" value="reset">&nbsp;&nbsp;&nbsp;
            <a href="register.html">没有账号?点击注册</a>
        </div>
    </form>
</div>

</body>
</html>

 login.css

* {
    margin: 0;
    padding: 0;
}

html {
    height: 100%;
    width: 100%;
    overflow: hidden;
    margin: 0;
    padding: 0;
    background: url(../imgs/Desert.jpg) no-repeat 0px 0px;
    background-repeat: no-repeat;
    background-size: 100% 100%;
    -moz-background-size: 100% 100%;
}

body {
    display: flex;
    align-items: center;
    justify-content: center;
    height: 100%;
}

#loginDiv {
    width: 37%;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 300px;
    background-color: rgba(75, 81, 95, 0.3);
    box-shadow: 7px 7px 17px rgba(52, 56, 66, 0.5);
    border-radius: 5px;
}

#name_trip {
    margin-left: 50px;
    color: red;
}

p {
    margin-top: 30px;
    margin-left: 20px;
    color: azure;
}

input {
    margin-left: 15px;
    border-radius: 5px;
    border-style: hidden;
    height: 30px;
    width: 140px;
    background-color: rgba(216, 191, 216, 0.5);
    outline: none;
    color: #f0edf3;
    padding-left: 10px;
}
#username{
    width: 200px;
}
#password{
    width: 202px;
}
.button {
    border-color: cornsilk;
    background-color: rgba(100, 149, 237, .7);
    color: aliceblue;
    border-style: hidden;
    border-radius: 5px;
    width: 100px;
    height: 31px;
    font-size: 16px;
}

#subDiv {
    text-align: center;
    margin-top: 30px;
}
#loginMsg{
    text-align: center;color: aliceblue;
}

 创建 db1 数据库,创建 tb_user 表,创建 User 实体类

-- 创建数据库
create database db1 character set utf8;
use db1;

-- 创建用户表
CREATE TABLE tb_user(
	id int primary key auto_increment,
	username varchar(20) unique,
	password varchar(32)
);

-- 添加数据
INSERT INTO tb_user(username,password) values('zhangsan','123'),('lisi','234');

SELECT * FROM tb_user;

 

package com.ruochen.pojo;

public class User {

    private Integer id;
    private String username;
    private String password;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

导入MyBatis 坐标,MySQL 驱动坐标

        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.5</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.34</version>
        </dependency>

 创建 mybatis-config.xml 核心配置文件,UserMapper.xml 映射文件,UserMapper 接口

  • mybatis-config.xml

 

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!--起别名-->
    <typeAliases>
        <package name="com.ruochen.pojo"/>
    </typeAliases>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql:///db1?useSSL=false&amp;useServerPrepStmts=true"/>
                <property name="username" value="root"/>
                <property name="password" value="ruochen666"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--扫描mapper-->
        <package name="com.ruochen.mapper"/>
    </mappers>
</configuration>

 UserMapper.xml

 

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.ruochen.mapper.UserMapper">

</mapper>

UserMapper.java

package com.ruochen.mapper;

public interface UserMapper {

}

目录树如下

 

 

流程

  • UserMapper.java
package com.ruochen.mapper;

import com.ruochen.pojo.User;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

public interface UserMapper {

    /**
     * 根据用户名和密码查询用户对象
     * @param username
     * @param password
     * @return
     */
    @Select("select * from tb_user where username= #{username} and password = #{password}")
    User select(@Param("username") String username, @Param("password") String password);
}

 UserServlet.java

 

package com.ruochen.web;

import com.ruochen.mapper.UserMapper;
import com.ruochen.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1. 接收用户名和密码
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        // 2. 调用 MyBatis 完成查询
        // 2.1 获取 SqlSessionFactory 对象
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        // 2.2 获取 SqlSession 对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        // 2.3 获取 Mapper
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        // 2.4 调用方法
        User user = userMapper.select(username, password);
        // 2.5 释放资源
        sqlSession.close();

        // 获取字符输出流,并设置 content-type
        response.setContentType("text/html;charset=utf-8");
        PrintWriter writer = response.getWriter();
        // 3. 判断 User 是否为 null
        if (user != null) {
            // 登录成功
            writer.write("登录成功");
        } else {
            // 登录失败
            writer.write("登录失败");
        }
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

用户注册案例

  • register.html
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>欢迎注册</title>
    <link href="css/register.css" rel="stylesheet">
</head>
<body>

<div class="form-div">
    <div class="reg-content">
        <h1>欢迎注册</h1>
        <span>已有帐号?</span> <a href="login.html">登录</a>
    </div>
    <form id="reg-form" action="#" method="get">

        <table>

            <tr>
                <td>用户名</td>
                <td class="inputs">
                    <input name="username" type="text" id="username">
                    <br>
                    <span id="username_err" class="err_msg" style="display: none">用户名不太受欢迎</span>
                </td>

            </tr>

            <tr>
                <td>密码</td>
                <td class="inputs">
                    <input name="password" type="password" id="password">
                    <br>
                    <span id="password_err" class="err_msg" style="display: none">密码格式有误</span>
                </td>
            </tr>


        </table>

        <div class="buttons">
            <input value="注 册" type="submit" id="reg_btn">
        </div>
        <br class="clear">
    </form>

</div>
</body>
</html>

 UserMapper.java

    /**
     * 根据用户名查询用户对象
     * @param username
     * @return
     */
    @Select("select * from tb_user where username = #{username}")
    User selectByUserName(String username);

    /**
     * 添加用户
     * @param user
     */
    @Insert("insert into tb_user values (null, #{username}, #{password});")
    void add(User user);

 RegisterServlet

package com.ruochen.web;

import com.ruochen.mapper.UserMapper;
import com.ruochen.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.io.InputStream;

@WebServlet("/registerServlet")
public class RegisterServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1. 接收用户数据
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        // 封装用户对象
        User user = new User();
        user.setUsername(username);
        user.setPassword(password);

        // 2. 调用 Mapper 根据用户名查询用户对象
        // 2.1 获取 SqlSessionFactory 对象
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        // 2.2 获取 SqlSession 对象
        SqlSession sqlSession = sqlSessionFactory.openSession();
        // 2.3 获取 Mapper
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        // 2.4 调用方法
        User u = userMapper.selectByUserName(username);

        // 3. 判断用户对象是否为 null
        if (u == null) {
            // 用户名不存在,添加用户
            userMapper.add(user);
            // 提交事务
            sqlSession.commit();
        } else {
            // 用户名存在,给出提示信息
            response.setContentType("text/html;charset=utf-8");
            response.getWriter().write("用户名已存在");
        }
        // 释放资源
        sqlSession.close();
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

代码优化

  • 创建 SqlSessionFactory 代码优化
    • 代码重复:工具类
    • SqlSessionFacroty 工厂只创建一次,不要重复创建:静态代码块

 

package com.ruochen.util;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

public class SqlSessionFactoryUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static {
        // 静态代码块会随着类的加载自动执行,且只执行一次

        try {
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    public static SqlSessionFactory getSqlSessionFactory() {
        return sqlSessionFactory;
    }
}

案例

准备工作

  • 创建新的模块 brand_demo,引入坐标

 

 

 

 pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.ruochen</groupId>
    <artifactId>brand-demo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>

    <dependencies>
        <!--mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.5.5</version>
        </dependency>

        <!--mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.34</version>
        </dependency>

        <!--servlet-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

        <!--jsp-->
        <dependency>
            <groupId>javax.servlet.jsp</groupId>
            <artifactId>jsp-api</artifactId>
            <version>2.2</version>
            <scope>provided</scope>
        </dependency>

        <!--jstl-->
        <dependency>
            <groupId>jstl</groupId>
            <artifactId>jstl</artifactId>
            <version>1.2</version>
        </dependency>

        <!--standard-->
        <!--jstl 1.2 版本不需要此依赖-->
        <!--
        <dependency>
            <groupId>taglibs</groupId>
            <artifactId>standard</artifactId>
            <version>1.1.2</version>
        </dependency>
        -->
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.tomcat.maven</groupId>
                <artifactId>tomcat7-maven-plugin</artifactId>
                <version>2.1</version>
            </plugin>
        </plugins>
    </build>

</project>

创建三层架构的包结构

 数据库表 tb_brand

-- 创建数据库
create database db1 character set utf8;
use db1;

-- 删除tb_brand表
drop table if exists tb_brand;
-- 创建tb_brand表
create table tb_brand
(
    -- id 主键
    id           int primary key auto_increment,
    -- 品牌名称
    brand_name   varchar(20),
    -- 企业名称
    company_name varchar(20),
    -- 排序字段
    ordered      int,
    -- 描述信息
    description  varchar(100),
    -- 状态:0:禁用  1:启用
    status       int
);
-- 添加数据
insert into tb_brand (brand_name, company_name, ordered, description, status)
values ('三只松鼠', '三只松鼠股份有限公司', 5, '好吃不上火', 0),
       ('华为', '华为技术有限公司', 100, '华为致力于把数字世界带入每个人、每个家庭、每个组织,构建万物互联的智能世界', 1),
       ('小米', '小米科技有限公司', 50, 'are you ok', 1);


SELECT * FROM tb_brand;

 实体类 Brand

package com.ruochen.pojo;

/**
 * 品牌实体类
 */

public class Brand {
    // id 主键
    private Integer id;
    // 品牌名称
    private String brandName;
    // 企业名称
    private String companyName;
    // 排序字段
    private Integer ordered;
    // 描述信息
    private String description;
    // 状态:0:禁用  1:启用
    private Integer status;


    public Brand() {
    }

    public Brand(Integer id, String brandName, String companyName, String description) {
        this.id = id;
        this.brandName = brandName;
        this.companyName = companyName;
        this.description = description;
    }

    public Brand(Integer id, String brandName, String companyName, Integer ordered, String description, Integer status) {
        this.id = id;
        this.brandName = brandName;
        this.companyName = companyName;
        this.ordered = ordered;
        this.description = description;
        this.status = status;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getBrandName() {
        return brandName;
    }

    public void setBrandName(String brandName) {
        this.brandName = brandName;
    }

    public String getCompanyName() {
        return companyName;
    }

    public void setCompanyName(String companyName) {
        this.companyName = companyName;
    }

    public Integer getOrdered() {
        return ordered;
    }

    public void setOrdered(Integer ordered) {
        this.ordered = ordered;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public Integer getStatus() {
        return status;
    }

    public void setStatus(Integer status) {
        this.status = status;
    }

    @Override
    public String toString() {
        return "Brand{" +
                "id=" + id +
                ", brandName='" + brandName + '\'' +
                ", companyName='" + companyName + '\'' +
                ", ordered=" + ordered +
                ", description='" + description + '\'' +
                ", status=" + status +
                '}';
    }
}

 MyBatis 基础环境

  • MyBatis-config.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!--起别名-->
    <typeAliases>
        <package name="com.ruochen.pojo"/>
    </typeAliases>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url"
                      value="jdbc:mysql:///db1?useSSL=false&amp;useServerPrepStmts=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/>
                <property name="username" value="root"/>
                <property name="password" value="ruochen666"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--扫描mapper-->
        <package name="com.ruochen.mapper"/>
    </mappers>
</configuration>

 BrandMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.ruochen.mapper.BrandMapper">

</mapper>

 BrandMapper 接口

package com.ruochen.mapper;

public interface BrandMapper {
}

 目录树如下

 

 

 业务 - 查询所有

 

 

Dao 层:BrandMapper 

 

    /**
     * 查询所有
     * @return
     */
    @Select("select * from tb_brand")
    @ResultMap("brandResultMap")
    List<Brand> selectAll();

 BrandMapper.xml

 

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.ruochen.mapper.BrandMapper">

    <resultMap id="brandResultMap" type="brand">
        <result column="brand_name" property="brandName"></result>
        <result column="company_name" property="companyName"></result>
    </resultMap>
</mapper>

 工具类:SqlSessionFactoryUtils

package com.ruochen.utils;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;

public class SqlSessionFactoryUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static {
        //静态代码块会随着类的加载而自动执行,且只执行一次

        try {
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    public static SqlSessionFactory getSqlSessionFactory(){
        return sqlSessionFactory;
    }
}

 Service 层:BrandService

 

package com.ruochen.service;

import com.ruochen.mapper.BrandMapper;
import com.ruochen.pojo.Brand;
import com.ruochen.utils.SqlSessionFactoryUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

import java.util.List;

public class BrandService {
    // 1. 获取 sqlSessionFactory
    SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();

    /**
     * 查询所有功能
     * @return
     */
    public List<Brand> selectAll() {
        // 调用BrandMapper.selectAll()
        // 2. 获取 SqlSession
        SqlSession sqlSession = factory.openSession();
        // 3. 获取 BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
        // 4. 调用方法
        List<Brand> brands = mapper.selectAll();
        // 5. 释放资源
        sqlSession.close();

        return brands;
    }
}

Web 层

  • index.html
<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Title</title>
    </head>
    <body>
        <a href="/brand-demo/selectAllServlet">查询所有</a>

    </body>
</html>

 SelectAllServlet

 

package com.ruochen.web;

import com.ruochen.pojo.Brand;
import com.ruochen.service.BrandService;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

@WebServlet("/selectAllServlet")
public class SelectAllServlet extends HttpServlet {
	private BrandService brandService = new BrandService();
	
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1. 调用 BrandService 完成查询
        List<Brand> brands = brandService.selectAll();

        // 2. 存入request域中
        request.setAttribute("brand", brands);

        // 3. 转发到 brand.jsp
        request.getRequestDispatcher("/brand.jsp").forward(request, response);

    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

brand.jsp

<%--
  Created by IntelliJ IDEA.
  User: ruochen
  Date: 2022/2/27
  Time: 12:33
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
    <head>
        <title>Title</title>
    </head>
    <body>
        <input type="button" value="新增"><br>
        <hr>
        <table border="1" cellspacing="0" width="80%">
            <tr>
                <th>序号</th>
                <th>品牌名称</th>
                <th>企业名称</th>
                <th>排序</th>
                <th>品牌介绍</th>
                <th>状态</th>
                <th>操作</th>
            </tr>

            <c:forEach items="${brands}" var="brand" varStatus="status">
                <tr align="center">
                    <td>${status.count}</td>
                    <td>${brand.brandName}</td>
                    <td>${brand.companyName}</td>
                    <td>${brand.ordered}</td>
                    <td>${brand.description}</td>
                    <c:if test="${brand.status == 1}">
                        <td>启用</td>
                    </c:if>
                    <c:if test="${brand.status != 1}">
                        <td>禁用</td>
                    </c:if>

                    <td><a href="#">修改</a> <a href="#">删除</a></td>
                </tr>
            </c:forEach>
        </table>
    </body>
</html>

 测试

 

 注意点:resultMap 的使用:属性名称和数据库字段名称不一致

业务 - 添加 

 

 Dao 层:BrandMapper

 

    @Insert("insert into tb_brand values (null, #{brandName}, #{companyName}, #{ordered}, #{description}, #{status});")
    void add(Brand brand);

Service 层:BrandService

 

    /**
     * 添加
     * @param brand
     */
    public void add(Brand brand) {
        // 2. 获取 SqlSession
        SqlSession sqlSession = factory.openSession();
        // 3. 获取 BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
        // 4. 调用方法
        mapper.add(brand);

        // 提交事务
        sqlSession.commit();

        // 释放资源
        sqlSession.close();
    }

 Web 层:brand.jsp

<%--
  Created by IntelliJ IDEA.
  User: ruochen
  Date: 2022/2/27
  Time: 12:33
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
    <head>
        <title>Title</title>
    </head>
    <body>
        <input type="button" value="新增" id="add"><br>
        <hr>
        <table border="1" cellspacing="0" width="80%">
            <tr>
                <th>序号</th>
                <th>品牌名称</th>
                <th>企业名称</th>
                <th>排序</th>
                <th>品牌介绍</th>
                <th>状态</th>
                <th>操作</th>
            </tr>

            <c:forEach items="${brands}" var="brand" varStatus="status">
                <tr align="center">
                    <td>${status.count}</td>
                    <td>${brand.brandName}</td>
                    <td>${brand.companyName}</td>
                    <td>${brand.ordered}</td>
                    <td>${brand.description}</td>
                    <c:if test="${brand.status == 1}">
                        <td>启用</td>
                    </c:if>
                    <c:if test="${brand.status != 1}">
                        <td>禁用</td>
                    </c:if>

                    <td><a href="#">修改</a> <a href="#">删除</a></td>
                </tr>
            </c:forEach>
        </table>
    </body>

    <script>
        document.getElementById("add").onclick = function () {
            location.href = "/brand-demo/addBrand.jsp";
        }
    </script>
</html>

 addBrand.jsp

 

<%--
  Created by IntelliJ IDEA.
  User: ruochen
  Date: 2022/2/27
  Time: 13:32
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
    <head>
        <meta charset="UTF-8">
        <title>添加品牌</title>
    </head>
    <body>
        <h3>添加品牌</h3>
        <form action="/brand-demo/AddServlet" method="post">
            品牌名称:<input name="brandName"><br>
            企业名称:<input name="companyName"><br>
            排序:<input name="ordered"><br>
            描述信息:<textarea rows="5" cols="20" name="description"></textarea><br>
            状态:
            <input type="radio" name="status" value="0">禁用
            <input type="radio" name="status" value="1">启用<br>

            <input type="submit" value="提交">
        </form>
    </body>
</html>

AddBrandServlet

 

package com.ruochen.web;

import com.ruochen.pojo.Brand;
import com.ruochen.service.BrandService;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet("/addServlet")
public class AddServlet extends HttpServlet {
    private BrandService service = new BrandService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1. 接收表单提交的数据,封装为一个 Brand 对象
        String brandName = request.getParameter("brandName");
        String companyName = request.getParameter("companyName");
        String ordered = request.getParameter("ordered");
        String description = request.getParameter("description");
        String status = request.getParameter("status");

        Brand brand = new Brand();
        brand.setBrandName(brandName);
        brand.setCompanyName(companyName);
        brand.setOrdered(Integer.parseInt(ordered));
        brand.setDescription(description);
        brand.setStatus(Integer.parseInt(status));

        // 2. 调用 service 完成添加
        service.add(brand);

        // 3. 转发到查询所有 Servlet
        request.getRequestDispatcher("/selectAllServlet").forward(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

测试

 

 业务 - 修改(数据回显)

 

 Dao 层:BrandMapper

    /**
     * 根据 id 查询
     * @param id
     * @return
     */
    @Select("select * from tb_brand where id = #{id}")
    @ResultMap("brandResultMap")
    Brand selectById(int id);

 Service 层:BrandService

 

    /**
     * 根据 id 查询
     * @param id
     * @return
     */
    public Brand selectById(int id) {
        // 调用BrandMapper.selectAll()
        // 2. 获取 SqlSession
        SqlSession sqlSession = factory.openSession();
        // 3. 获取 BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
        // 4. 调用方法
        Brand brand = mapper.selectById(id);
        // 5. 释放资源
        sqlSession.close();

        return brand;
    }

Web 层:brand.jsp

<td><a href="/brand-demo/selectByIdServlet?id=${brand.id}">修改</a> <a href="#">删除</a></td>

 SelectByIdServlet

package com.ruochen.web;

import com.ruochen.pojo.Brand;
import com.ruochen.service.BrandService;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/selectByIdServlet")
public class SelectByIdServlet extends HttpServlet {
    private BrandService brandService = new BrandService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1. 接收id
        String id = request.getParameter("id");
        // 2. 调用 service
        Brand brand = brandService.selectById(Integer.parseInt(id));
        // 3. 存储到 request 中
        request.setAttribute("brand", brand);
        // 4. 转发到 update.jsp
        request.getRequestDispatcher("/update.jsp").forward(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

 update.jsp

<%--
  Created by IntelliJ IDEA.
  User: ruochen
  Date: 2022/2/27
  Time: 13:32
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
    <head>
        <meta charset="UTF-8">
        <title>修改品牌</title>
    </head>
    <body>
        <h3>修改品牌</h3>
        <form action="#" method="post">
            品牌名称:<input name="brandName" value="${brand.brandName}"><br>
            企业名称:<input name="companyName" value="${brand.companyName}"><br>
            排序:<input name="ordered" value="${brand.ordered}"><br>
            描述信息:<textarea rows="5" cols="20" name="description">${brand.description}</textarea><br>
            状态:
            <c:if test="${brand.status == 0}">
                <input type="radio" name="status" value="0" checked>禁用
                <input type="radio" name="status" value="1">启用<br>
            </c:if>
            <c:if test="${brand.status == 1}">
                <input type="radio" name="status" value="0">禁用
                <input type="radio" name="status" value="1" checked>启用<br>
            </c:if>

            <input type="submit" value="提交">
        </form>
    </body>
</html>

测试

 

 业务 - 修改(修改数据)

 

 Dao 层:BrandMapper

 

    /**
     * 修改
     * @param brand
     */
    @Update("update tb_brand set brand_name = #{brandName}, company_name = #{companyName}, ordered = #{ordered}, " +
            "description = #{description}, status = #{status} where id = #{id}")
    void update(Brand brand);

Service 层:BrandService

 

    /**
     * 修改
     * @param brand
     */
    public void update(Brand brand) {
        // 2. 获取 SqlSession
        SqlSession sqlSession = factory.openSession();
        // 3. 获取 BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
        // 4. 调用方法
        mapper.update(brand);

        // 提交事务
        sqlSession.commit();

        // 释放资源
        sqlSession.close();
    }

Web 层:update.jsp

<%--
  Created by IntelliJ IDEA.
  User: ruochen
  Date: 2022/2/27
  Time: 13:32
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
    <head>
        <meta charset="UTF-8">
        <title>修改品牌</title>
    </head>
    <body>
        <h3>修改品牌</h3>
        <form action="/brand-demo/updateServlet" method="post">
            <%-- 隐藏域,提交 id --%>
            <input type="hidden" name="id" value="${brand.id}">
                
            品牌名称:<input name="brandName" value="${brand.brandName}"><br>
            企业名称:<input name="companyName" value="${brand.companyName}"><br>
            排序:<input name="ordered" value="${brand.ordered}"><br>
            描述信息:<textarea rows="5" cols="20" name="description">${brand.description}</textarea><br>
            状态:
            <c:if test="${brand.status == 0}">
                <input type="radio" name="status" value="0" checked>禁用
                <input type="radio" name="status" value="1">启用<br>
            </c:if>
            <c:if test="${brand.status == 1}">
                <input type="radio" name="status" value="0">禁用
                <input type="radio" name="status" value="1" checked>启用<br>
            </c:if>

            <input type="submit" value="提交">
        </form>
    </body>
</html>

 updateServlet

package com.ruochen.web;

import com.ruochen.pojo.Brand;
import com.ruochen.service.BrandService;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/updateServlet")
public class UpdateServlet extends HttpServlet {
    private BrandService service = new BrandService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        // 处理 post 请求的乱码问题
        request.setCharacterEncoding("utf-8");

        // 1. 接收表单提交的数据,封装为一个 Brand 对象
        String id = request.getParameter("id");
        String brandName = request.getParameter("brandName");
        String companyName = request.getParameter("companyName");
        String ordered = request.getParameter("ordered");
        String description = request.getParameter("description");
        String status = request.getParameter("status");

        Brand brand = new Brand();
        brand.setId(Integer.parseInt(id));
        brand.setBrandName(brandName);
        brand.setCompanyName(companyName);
        brand.setOrdered(Integer.parseInt(ordered));
        brand.setDescription(description);
        brand.setStatus(Integer.parseInt(status));

        // 2. 调用 service 完成修改
        service.update(brand);

        // 3. 转发到查询所有 Servlet
        request.getRequestDispatcher("/selectAllServlet").forward(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

 测试

 

业务 - 删除 

Dao 层:BrandMapper 

 

    /**
     * 删除
     * @param id
     */
    @Delete("delete from tb_brand where id = #{id}")
    void delete(int id);

Service 层:BrandService

    /**
     * 删除
     * @param id
     */
    public void delete(int id) {
        // 2. 获取 SqlSession
        SqlSession sqlSession = factory.openSession();
        // 3. 获取 BrandMapper
        BrandMapper mapper = sqlSession.getMapper(BrandMapper.class);
        // 4. 调用方法
        mapper.delete(id);

        // 提交事务
        sqlSession.commit();

        // 释放资源
        sqlSession.close();
    }

 

Web 层:brand.jsp

<td><a href="/brand-demo/selectByIdServlet?id=${brand.id}">修改</a> <a
href="/brand-demo/deleteServlet?id=${brand.id}">删除</a></td>

DeleteServlet

package com.ruochen.web;

import com.ruochen.pojo.Brand;
import com.ruochen.service.BrandService;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

@WebServlet("/deleteServlet")
public class DeleteServlet extends HttpServlet {
    private BrandService service = new BrandService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1. 接收 id
        String id = request.getParameter("id");
        // 2. 调用 service
        service.delete(Integer.parseInt(id));
        // 3. 转发到查询所有 Servlet
        request.getRequestDispatcher("/selectAllServlet").forward(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

 测试

 

业务 - 用户登录 

 

Dao 层:UserMapper.java 

 

package com.ruochen.mapper;

import com.ruochen.pojo.User;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;

public interface UserMapper {


    /**
     * 根据用户名和密码查询用户对象
     * @param username
     * @param password
     * @return
     */
    @Select("select * from tb_user where username = #{username} and password = #{password}")
    User select(@Param("username") String username,@Param("password")  String password);

    /**
     * 根据用户名查询用户对象
     * @param username
     * @return
     */
    @Select("select * from tb_user where username = #{username}")
    User selectByUsername(String username);

    /**
     * 添加用户
     * @param user
     */
    @Insert("insert into tb_user values(null,#{username},#{password})")
    void add(User user);
}

User.java

package com.ruochen.pojo;

public class User {

    private Integer id;
    private String username;
    private String password;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.ruochen.mapper.UserMapper">

</mapper>

 Service 层:UserService.java

package com.ruochen.service;

import com.ruochen.mapper.UserMapper;
import com.ruochen.pojo.User;
import com.ruochen.utils.SqlSessionFactoryUtils;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

public class UserService {
    SqlSessionFactory factory = SqlSessionFactoryUtils.getSqlSessionFactory();

    /**
     * 登录方法
     * @param username
     * @param password
     * @return
     */
    public User login(String username, String password) {
        // 2. 获取 SqlSession
        SqlSession sqlSession = factory.openSession();
        // 3. 获取 UserMapper
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        // 4. 调用方法
        User user = mapper.select(username, password);
        // 5. 释放资源
        sqlSession.close();

        return user;
    }
}

 Web 层:login.jsp

 

<%--
  Created by IntelliJ IDEA.
  User: ruochen
  Date: 2022/2/27
  Time: 15:45
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>

    <head>
        <meta charset="UTF-8">
        <title>login</title>
        <link href="css/login.css" rel="stylesheet">
    </head>

    <body>
        <div id="loginDiv" style="height: 350px">
            <form action="/brand-demo/loginServlet" id="form">
                <h1 id="loginMsg">LOGIN IN</h1>
                <div id="errorMsg">${login_msg}</div>
                <p>Username:<input id="username" name="username" type="text"></p>

                <p>Password:<input id="password" name="password" type="password"></p>
                <p>Remember:<input id="remember" name="remember" type="checkbox"></p>
                <div id="subDiv">
                    <input type="submit" class="button" value="login up">
                    <input type="reset" class="button" value="reset">&nbsp;&nbsp;&nbsp;
                    <a href="register.html">没有账号?</a>
                </div>
            </form>
        </div>

    </body>
</html>

brand.jsp 添加

<h1>${user.username},欢迎您</h1>

 LoginServlet

 

package com.ruochen.web;

import com.ruochen.pojo.User;
import com.ruochen.service.UserService;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
    private UserService service = new UserService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1. 获取用户名和密码
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        // 2. 调用 service 查询
        User user = service.login(username, password);

        // 3. 判断
        if (user != null) {
            // 登录成功,,跳转到查询所有的 BrandServlet

            // 将登录成功的user对象存储到 session
            HttpSession session = request.getSession();
            session.setAttribute("user", user);

            String contextPath = request.getContextPath();
            response.sendRedirect(contextPath + "/selectAllServlet");
        } else {
            // 登录失败

            // 存储错误信息到 request
            request.setAttribute("login_msg", "用户名或密码错误");

            // 跳转到 login.jsp
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        }
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

 测试

 

 

业务 - 记住用户

  • 如何自动填充用户名和密码?
    • 将用户名和密码写入Cookie中,并且持久化存储 Cookie,下次访问浏览器会自动携带 Cookie
    • 在页面获取 Cookie 数据后,设置到用户名和密码框中
  • 何时写 Cookie?
    • 登录成功
    • 用户勾选记住用户复选框
  • LoginServlet


 

package com.ruochen.web;

import com.ruochen.pojo.User;
import com.ruochen.service.UserService;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;

@WebServlet("/loginServlet")
public class LoginServlet extends HttpServlet {
    private UserService service = new UserService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1. 获取用户名和密码
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        // 获取复选框数据
        String remember = request.getParameter("remember");

        // 2. 调用 service 查询
        User user = service.login(username, password);

        // 3. 判断
        if (user != null) {
            // 登录成功,,跳转到查询所有的 BrandServlet

            // 判断用户是否勾选记住我
            if ("1".equals(remember)) {
                // 勾选了,发送 Cookie

                // 1. 创建 Cookie 对象
                Cookie c_username = new Cookie("username", username);
                Cookie c_password = new Cookie("password", password);
                // 设置 Cookie 存活时间
                c_username.setMaxAge(60 * 60 * 24 * 7);
                c_password.setMaxAge(60 * 60 * 24 * 7);
                // 2. 发送 Cookie
                response.addCookie(c_username);
                response.addCookie(c_password);
            }
            // 将登录成功的user对象存储到 session
            HttpSession session = request.getSession();
            session.setAttribute("user", user);

            String contextPath = request.getContextPath();
            response.sendRedirect(contextPath + "/selectAllServlet");
        } else {
            // 登录失败

            // 存储错误信息到 request
            request.setAttribute("login_msg", "用户名或密码错误");

            // 跳转到 login.jsp
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        }
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

login.jsp

<%--
  Created by IntelliJ IDEA.
  User: ruochen
  Date: 2022/2/27
  Time: 15:45
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>

    <head>
        <meta charset="UTF-8">
        <title>login</title>
        <link href="css/login.css" rel="stylesheet">
    </head>

    <body>
        <div id="loginDiv" style="height: 350px">
            <form action="/brand-demo/loginServlet" method="post" id="form">
                <h1 id="loginMsg">LOGIN IN</h1>
                <div id="errorMsg">${login_msg}</div>
                <p>Username:<input id="username" name="username" value="${cookie.username.value}" type="text"></p>

                <p>Password:<input id="password" name="password" value="${cookie.password.value}" type="password"></p>
                <p>Remember:<input id="remember" name="remember" value="1" type="checkbox"></p>
                <div id="subDiv">
                    <input type="submit" class="button" value="login up">
                    <input type="reset" class="button" value="reset">&nbsp;&nbsp;&nbsp;
                    <a href="register.html">没有账号?</a>
                </div>
            </form>
        </div>

    </body>
</html>

 测试

 

 业务 - 注册

 

 

 UserService.java

    /**
     * 注册方法
     *
     * @param user
     * @return
     */
    public boolean register(User user) {
        // 2. 获取 SqlSession
        SqlSession sqlSession = factory.openSession();
        // 3. 获取 UserMapper
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        // 4. 判断用户名是否存在
        User u = mapper.selectByUsername(user.getUsername());
        if (u == null) {
            // 用户名不存在,注册
            mapper.add(user);
            sqlSession.commit();
        }
        sqlSession.close();
        return u == null;
    }

 register.jsp

<%--
  Created by IntelliJ IDEA.
  User: ruochen
  Date: 2022/2/27
  Time: 16:24
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
    <head>
        <meta charset="UTF-8">
        <title>欢迎注册</title>
        <link href="css/register.css" rel="stylesheet">
    </head>
    <body>

        <div class="form-div">
            <div class="reg-content">
                <h1>欢迎注册</h1>
                <span>已有帐号?</span> <a href="login.html">登录</a>
            </div>
            <form id="reg-form" action="/brand-demo/registerServlet" method="post">

                <table>

                    <tr>
                        <td>用户名</td>
                        <td class="inputs">
                            <input name="username" type="text" id="username">
                            <br>
                        	<span id="username_err" class="err_msg">${register_msg}</span>
                        </td>

                    </tr>

                    <tr>
                        <td>密码</td>
                        <td class="inputs">
                            <input name="password" type="password" id="password">
                            <br>
                            <span id="password_err" class="err_msg" style="display: none">密码格式有误</span>
                        </td>
                    </tr>


                    <tr>
                        <td>验证码</td>
                        <td class="inputs">
                            <input name="checkCode" type="text" id="checkCode">
                            <img src="imgs/a.jpg">
                            <a href="#" id="changeImg">看不清?</a>
                        </td>
                    </tr>

                </table>

                <div class="buttons">
                    <input value="注 册" type="submit" id="reg_btn">
                </div>
                <br class="clear">
            </form>

        </div>
    </body>
</html>

 login.jsp 添加

 

<div id="errorMsg">${login_msg} ${register_msg}</div>
<a href="register.jsp">没有账号?</a>

RegisterServlet

 

package com.ruochen.web;

import com.ruochen.pojo.User;
import com.ruochen.service.UserService;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import java.io.IOException;

@WebServlet("/registerServlet")
public class RegisterServlet extends HttpServlet {
    private UserService service = new UserService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1. 获取用户名和密码
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        User user = new User();
        user.setUsername(username);
        user.setPassword(password);

        // 2. 调用 service 注册
        boolean flag = service.register(user);
        // 3. 判断注册成功与否
        if (flag) {
            // 注册成功,跳转登录页面
            request.setAttribute("register_msg", "注册成功,请登录");
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        } else {
            // 注册失败,跳转到注册页面
            request.setAttribute("register_msg", "用户名已存在");
            request.getRequestDispatcher("/register.jsp").forward(request, response);
        }
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

测试 

 

 

业务 - 注册验证码 

 

 验证码工具类:checkCodeUtil.java

 

package com.ruochen.utils;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.Arrays;
import java.util.Random;

/**
 * 生成验证码工具类
 */
public class CheckCodeUtil {

    public static final String VERIFY_CODES = "123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    private static Random random = new Random();

    /**
     * 输出随机验证码图片流,并返回验证码值(一般传入输出流,响应response页面端,Web项目用的较多)
     *
     * @param w          图片宽度
     * @param h          图片高度
     * @param os         输出流
     * @param verifySize 数据长度
     * @return 验证码数据
     * @throws IOException
     */
    public static String outputVerifyImage(int w, int h, OutputStream os, int verifySize) throws IOException {
        String verifyCode = generateVerifyCode(verifySize);
        outputImage(w, h, os, verifyCode);
        return verifyCode;
    }

    /**
     * 使用系统默认字符源生成验证码
     *
     * @param verifySize 验证码长度
     * @return
     */
    public static String generateVerifyCode(int verifySize) {
        return generateVerifyCode(verifySize, VERIFY_CODES);
    }

    /**
     * 使用指定源生成验证码
     *
     * @param verifySize 验证码长度
     * @param sources    验证码字符源
     * @return
     */
    public static String generateVerifyCode(int verifySize, String sources) {
        // 未设定展示源的字码,赋默认值大写字母+数字
        if (sources == null || sources.length() == 0) {
            sources = VERIFY_CODES;
        }
        int codesLen = sources.length();
        Random rand = new Random(System.currentTimeMillis());
        StringBuilder verifyCode = new StringBuilder(verifySize);
        for (int i = 0; i < verifySize; i++) {
            verifyCode.append(sources.charAt(rand.nextInt(codesLen - 1)));
        }
        return verifyCode.toString();
    }

    /**
     * 生成随机验证码文件,并返回验证码值 (生成图片形式,用的较少)
     *
     * @param w
     * @param h
     * @param outputFile
     * @param verifySize
     * @return
     * @throws IOException
     */
    public static String outputVerifyImage(int w, int h, File outputFile, int verifySize) throws IOException {
        String verifyCode = generateVerifyCode(verifySize);
        outputImage(w, h, outputFile, verifyCode);
        return verifyCode;
    }


    /**
     * 生成指定验证码图像文件
     *
     * @param w
     * @param h
     * @param outputFile
     * @param code
     * @throws IOException
     */
    public static void outputImage(int w, int h, File outputFile, String code) throws IOException {
        if (outputFile == null) {
            return;
        }
        File dir = outputFile.getParentFile();
        //文件不存在
        if (!dir.exists()) {
            //创建
            dir.mkdirs();
        }
        try {
            outputFile.createNewFile();
            FileOutputStream fos = new FileOutputStream(outputFile);
            outputImage(w, h, fos, code);
            fos.close();
        } catch (IOException e) {
            throw e;
        }
    }

    /**
     * 输出指定验证码图片流
     *
     * @param w
     * @param h
     * @param os
     * @param code
     * @throws IOException
     */
    public static void outputImage(int w, int h, OutputStream os, String code) throws IOException {
        int verifySize = code.length();
        BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        Random rand = new Random();
        Graphics2D g2 = image.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        // 创建颜色集合,使用java.awt包下的类
        Color[] colors = new Color[5];
        Color[] colorSpaces = new Color[]{Color.WHITE, Color.CYAN,
                Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA, Color.ORANGE,
                Color.PINK, Color.YELLOW};
        float[] fractions = new float[colors.length];
        for (int i = 0; i < colors.length; i++) {
            colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];
            fractions[i] = rand.nextFloat();
        }
        Arrays.sort(fractions);
        // 设置边框色
        g2.setColor(Color.GRAY);
        g2.fillRect(0, 0, w, h);

        Color c = getRandColor(200, 250);
        // 设置背景色
        g2.setColor(c);
        g2.fillRect(0, 2, w, h - 4);

        // 绘制干扰线
        Random random = new Random();
        // 设置线条的颜色
        g2.setColor(getRandColor(160, 200));
        for (int i = 0; i < 20; i++) {
            int x = random.nextInt(w - 1);
            int y = random.nextInt(h - 1);
            int xl = random.nextInt(6) + 1;
            int yl = random.nextInt(12) + 1;
            g2.drawLine(x, y, x + xl + 40, y + yl + 20);
        }

        // 添加噪点
        // 噪声率
        float yawpRate = 0.05f;
        int area = (int) (yawpRate * w * h);
        for (int i = 0; i < area; i++) {
            int x = random.nextInt(w);
            int y = random.nextInt(h);
            // 获取随机颜色
            int rgb = getRandomIntColor();
            image.setRGB(x, y, rgb);
        }
        // 添加图片扭曲
        shear(g2, w, h, c);

        g2.setColor(getRandColor(100, 160));
        int fontSize = h - 4;
        Font font = new Font("Algerian", Font.ITALIC, fontSize);
        g2.setFont(font);
        char[] chars = code.toCharArray();
        for (int i = 0; i < verifySize; i++) {
            AffineTransform affine = new AffineTransform();
            affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1), (w / verifySize) * i + fontSize / 2, h / 2);
            g2.setTransform(affine);
            g2.drawChars(chars, i, 1, ((w - 10) / verifySize) * i + 5, h / 2 + fontSize / 2 - 10);
        }

        g2.dispose();
        ImageIO.write(image, "jpg", os);
    }

    /**
     * 随机颜色
     *
     * @param fc
     * @param bc
     * @return
     */
    private static Color getRandColor(int fc, int bc) {
        if (fc > 255) {
            fc = 255;
        }
        if (bc > 255) {
            bc = 255;
        }
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }

    private static int getRandomIntColor() {
        int[] rgb = getRandomRgb();
        int color = 0;
        for (int c : rgb) {
            color = color << 8;
            color = color | c;
        }
        return color;
    }

    private static int[] getRandomRgb() {
        int[] rgb = new int[3];
        for (int i = 0; i < 3; i++) {
            rgb[i] = random.nextInt(255);
        }
        return rgb;
    }

    private static void shear(Graphics g, int w1, int h1, Color color) {
        shearX(g, w1, h1, color);
        shearY(g, w1, h1, color);
    }

    private static void shearX(Graphics g, int w1, int h1, Color color) {

        int period = random.nextInt(2);

        boolean borderGap = true;
        int frames = 1;
        int phase = random.nextInt(2);

        for (int i = 0; i < h1; i++) {
            double d = (double) (period >> 1)
                    * Math.sin((double) i / (double) period
                    + (6.2831853071795862D * (double) phase)
                    / (double) frames);
            g.copyArea(0, i, w1, 1, (int) d, 0);
            if (borderGap) {
                g.setColor(color);
                g.drawLine((int) d, i, 0, i);
                g.drawLine((int) d + w1, i, w1, i);
            }
        }

    }

    private static void shearY(Graphics g, int w1, int h1, Color color) {

        int period = random.nextInt(40) + 10; // 50;

        boolean borderGap = true;
        int frames = 20;
        int phase = 7;
        for (int i = 0; i < w1; i++) {
            double d = (double) (period >> 1)
                    * Math.sin((double) i / (double) period
                    + (6.2831853071795862D * (double) phase)
                    / (double) frames);
            g.copyArea(i, 0, 1, h1, 0, (int) d);
            if (borderGap) {
                g.setColor(color);
                g.drawLine(i, (int) d, i, 0);
                g.drawLine(i, (int) d + h1, i, h1);
            }

        }

    }
}

register.jsp

<tr>
    <td>验证码</td>
    <td class="inputs">
        <input name="checkCode" type="text" id="checkCode">
        <img id="checkCodeImg" src="/brand-demo/checkCodeServlet">
        <a href="#" id="changeImg">看不清?</a>
    </td>
</tr>
<script>
    document.getElementById("changeImg").onclick = function () {
        document.getElementById("checkCodeImg").src = "/brand-demo/checkCodeServlet?" + new Date().getMilliseconds();
    };

    document.getElementById("checkCodeImg").onclick = function () {
        document.getElementById("checkCodeImg").src = "/brand-demo/checkCodeServlet?" + new Date().getMilliseconds();
    };
</script>

 CheckCodeServlet.java

 

package com.ruochen.web;

import com.ruochen.utils.CheckCodeUtil;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

@WebServlet("/checkCodeServlet")
public class CheckCodeServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 生成验证码
        ServletOutputStream os = response.getOutputStream();
        String checkCode = CheckCodeUtil.outputVerifyImage(100, 50, os, 4);

        // 存入 session
        HttpSession session = request.getSession();
        session.setAttribute("checkCodeGen", checkCode);

    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

RegisterServlet.java

package com.ruochen.web;

import com.ruochen.pojo.User;
import com.ruochen.service.UserService;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import java.io.IOException;

@WebServlet("/registerServlet")
public class RegisterServlet extends HttpServlet {
    private UserService service = new UserService();

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 1. 获取用户名和密码
        String username = request.getParameter("username");
        String password = request.getParameter("password");

        User user = new User();
        user.setUsername(username);
        user.setPassword(password);

        // 获取用户输入的验证码
        String checkCode = request.getParameter("checkCode");

        // 程序生成的验证码,从 session 获取
        HttpSession session = request.getSession();
        String checkCodeGen = (String) session.getAttribute("checkCodeGen");

        // 比对
        if (!checkCodeGen.equalsIgnoreCase(checkCode)) {
            request.setAttribute("register_msg", "验证码错误");
            request.getRequestDispatcher("/register.jsp").forward(request, response);

            // 不允许注册
            return;
        }

        // 2. 调用 service 注册
        boolean flag = service.register(user);
        // 3. 判断注册成功与否
        if (flag) {
            // 注册成功,跳转登录页面
            request.setAttribute("register_msg", "注册成功,请登录");
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        } else {
            // 注册失败,跳转到注册页面
            request.setAttribute("register_msg", "用户名已存在");
            request.getRequestDispatcher("/register.jsp").forward(request, response);
        }
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request, response);
    }
}

 测试

 

 业务 - 登录验证

 

 LoginFilter

package com.ruochen.web.filter;

import javax.servlet.*;
import javax.servlet.annotation.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import java.io.IOException;

/**
 * 登录验证的过滤器
 */
@WebFilter("/*")
public class LoginFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws ServletException, IOException {

        HttpServletRequest req = (HttpServletRequest) request;
        // 判断访问资源路径是否和登录注册相关
        String[] urls = {"/login.jsp", "/imgs/", "/css/", "/loginServlet", "/register.jsp", "/registerServlet", "/checkCodeServlet"};
        // 获取当前访问的资源路径
        String url = req.getRequestURL().toString();
        // 循环判断
        for (String u : urls) {
            if (url.contains(u)) {
                // 包含
                // 放行
                chain.doFilter(request, response);
                return;
            }
        }

        // 1. 判断 session 中是否有 user
        HttpSession session = req.getSession();
        Object user = session.getAttribute("user");

        // 2. 判断user是否为 null
        if (user != null) {
            // 已登录
            // 放行
            chain.doFilter(request, response);
        } else {
            // 未登录,存储提示信息,跳转到登录页面
            req.setAttribute("login_msg", "您尚未登录!");
            req.getRequestDispatcher("/login.jsp").forward(req, response);
        }

    }

    public void init(FilterConfig config) throws ServletException {
    }

    public void destroy() {
    }

}

 测试