mybatis首个创建相关步骤

1。先关联数据库，用户，密码，数据库保持一致

2.添加包和类

1.User放和数据库属性一样的

package com.it.springbootmybatis01.pojo;

@lombok.Data
@lombok.AllArgsConstructor
@lombok.NoArgsConstructor
public class User {
    private Integer id;
    private String username;
    private String password;
    private String name;
    private String age;
}


2.UserMapper放数据库操作的注解

package com.it.springbootmybatis01.mapper;

import com.it.springbootmybatis01.pojo.User;
import org.apache.ibatis.annotations.*;

import java.util.List;

@Mapper//表示应用程序在运行过程中，会通过这个接口来创建一个实现类对象，这个对象就是MyBatis的代理对象，并且会把这个对象交给Spring容器IOC管理
public interface UserMapper {
    //查询所有用户
   // @Select("select * from user")
    public List<User> FindAll();
    @Delete("delete from user where id=#{id}")
    public void deleteById(Integer id);
    @Insert("insert into user(username,password,name,age) values(#{username},#{password},#{name},#{age})")
    public void insert(User user);
    @Update("update user set username=#{username},password=#{password},name=#{name},age=#{age} where id=#{id}")
    public void update(User user);
    @Select("select * from user where username=#{username} and password=#{password}")
    public User findByUsernameAndPassword(@Param("username") String username, @Param("password") String password);
    //多个形参要用@Param注解给形参起别名

}

3.UserMapper.xml放复杂的操作注解

<?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.it.springbootmybatis01.mapper.UserMapper">

    <select id="FindAll" resultType="com.it.springbootmybatis01.pojo.User">
        select id,username,password,name,age from user
    </select>

</mapper>

（注意包名和上面一样，文件名和接口名一样）

4.SpringbootMybatis01ApplicationTests放测试

package com.it.springbootmybatis01;

import com.it.springbootmybatis01.mapper.UserMapper;
import com.it.springbootmybatis01.pojo.User;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

@SpringBootTest//springboot测试类
class SpringbootMybatis01ApplicationTests {

   @Autowired
    private UserMapper userMapper;
   @Test
   public void testFindAll(){
       //调用方法
       List<User> userList = userMapper.FindAll();
      userList.forEach(System.out::println);

   }

    @Test
    public void testDeleteById(){
        //调用方法
         userMapper.deleteById(5);
    }
    @Test
    public void testInsert(){
        //调用方法
        User user = new User(null,"小明","123456","小明","18");
        userMapper.insert(user);
    }

    @Test
    public void testUpdate(){
        //调用方法
        User user = new User(2,"大红","123456","大红","18");
        userMapper.update(user);
    }
    @Test
    public void testFindByUsernameAndPassword(){
        //调用方法
        User user = userMapper.findByUsernameAndPassword("大红","123456");
        System.out.println(user);
    }

}

5.pom.xml放相关依赖

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.it</groupId>
    <artifactId>springboot-mybatis01</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springboot-mybatis01</name>
    <description>springboot-mybatis01</description>
    <properties>
        <java.version>17</java.version>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <spring-boot.version>3.0.2</spring-boot.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>3.0.0</version>
        </dependency>

        <dependency>
            <groupId>com.mysql</groupId>
            <artifactId>mysql-connector-j</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-dependencies</artifactId>
                <version>${spring-boot.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.8.1</version>
                <configuration>
                    <source>17</source>
                    <target>17</target>
                    <encoding>UTF-8</encoding>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <version>${spring-boot.version}</version>
                <configuration>
                    <mainClass>com.it.springbootmybatis01.SpringbootMybatis01Application</mainClass>
                    <skip>true</skip>
                </configuration>
                <executions>
                    <execution>
                        <id>repackage</id>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

</project>

6.配置文件application.properties

#下面这些内容是为了让MyBatis映射
#指定Mybatis的Mapper文件#如果没有按照要求建xml配置文件，需要在这里指定地址
mybatis.mapper-locations=classpath:mappers/*xml
#指定Mybatis的实体目录
mybatis.type-aliases-package=com.it.springbootmybatis01.mybatis.entity

#配置数据库的联接信息
spring.datasource.url=jdbc:mysql://localhost:3306/web01
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=q1q1q1q1q1q1

#配置MyBatis日志输出
mybatis.configuration.log-impl=org.apache.ibatis.logging.stdout.StdOutImpl