会话跟踪技术
Cookie
遇到这个问题：The server encountered an internal error that prevented it from fulfilling this request.
原因：在pom.xml文件下的servlet里面没有配置provided
发送Cookie
AServlet.java核心代码
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//创建cookie对象
Cookie cookie = new Cookie("username", "zc");
//2.发送cookie
resp.addCookie(cookie);
}
获取Cookie
BServlet.java核心代码
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//获取Cookie数组
Cookie[] cookies = req.getCookies();
//遍历数组获取cookie
for (Cookie cookie : cookies) {
//获取数据
String name = cookie.getName();
if ("username".equals(name)) {
String value= cookie.getValue();
System.out.println(name+":"+value);
break;
}
}
}
Cookie原理
Cookie细节
Cookie存活时间
细节：设置cookie存活时常要在发送cookie之前
Cookie存储中文
AServlet核心代码：
//将中文进行URL编码
String value="张成";
value=URLEncoder.encode(value,"UTF-8");
//创建cookie对象
Cookie cookie = new Cookie("username", value);
BServlet核心代码：
String value= cookie.getValue();
value= URLDecoder.decode(value,"UTF-8");
System.out.println(name+":"+value);
Session
SessionDemo1核心代码：
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
HttpSession session = req.getSession();
session.setAttribute("username","张成");
}
SessionDemo2核心代码：
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
HttpSession session = req.getSession();
Object attribute = session.getAttribute("username");
System.out.println(attribute);
}
Session原理
Session细节
Session数据若要共享，则不能关闭浏览器。因为若是关闭了浏览器再次访问同一个资源，两次的session是不一样的。
小结
案例
记住用户
LoginServlet.java核心代码
//获取复选框
String remember = request.getParameter("remember");
//判断用户是否勾选记住我
if ("1".equals(remember)) {
//勾选了，发送cookie
//1.创建对应cookie对象
Cookie c_username = new Cookie("username", username);
Cookie c_password = new Cookie("password", password);
//2.设置cookie的存活时间
c_username.setMaxAge(60 * 60 * 24 * 7);
c_password.setMaxAge(60 * 60 * 24 * 7);
//3.发送cookie
response.addCookie(c_username);
response.addCookie(c_password);
}
注册功能
注册
UserService.java核心代码
注册的方法：
public boolean register(User user){
//2. 获取SqlSession
SqlSession sqlSession = factory.openSession();
//3. 获取 UserMapper UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
//4.判断用户是否存在
User u = userMapper.selectByUsername(user.getUsername());
if ( u ==null){
//用户不存在
userMapper.add(user);
sqlSession.commit();
}
sqlSession.close();
return u==null;
}
RegisterServlet.java代码
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取用户名和密码
String username = request.getParameter("username");
String password = request.getParameter("password");
//封装对象
User user = new User();
user.setUsername(username);
user.setPassword(password);
//调用service注册
boolean flag = service.register(user);
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，跳转失败也没
request.setAttribute("register_msg", "用户名已存在");
request.getRequestDispatcher("/register.jsp").forward(request, response);
}
}
生成验证码
生成验证码的工具类
public class CheckCodeUtil {
public static final String VERIFY_CODES = "123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
private static Random random = new Random();
public static void main(String[] args) throws IOException {
OutputStream fos = new FileOutputStream("c://a.jpg");
String checkCode = CheckCodeUtil.outputVerifyImage(100, 50, fos, 4);
System.out.println(checkCode);
}
/**
* 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 width 图片宽度
* @param height 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 width, int height, OutputStream os, int verifySize) throws IOException {
String verifyCode = generateVerifyCode(verifySize);
outputImage(width, height, 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);
}
}
}
}
CheckCodeServlet.java的核心代码
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
ServletOutputStream os = response.getOutputStream();
String checkCode = CheckCodeUtil.outputVerifyImage(100, 50, os, 4);
}
当验证码图片看不清，要换一张时的核心代码
register.jsp
<script>
document.getElementById("changeImg").onclick = function () {
document.getElementById("checkCodeImg").src = "/brand-demo/checkCodeServlet?"+new Date().getMilliseconds();
}
</script>
校验验证码
CheckCodeServlet.java核心代码：
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);
}
RegisterServle.java核心代码：
//获取用户输入的验证码
String checkCode = request.getParameter("checkCode");
//获取程序生成的验证码
HttpSession session = request.getSession();
String checkCodeGen = (String) session.getAttribute("checkCodeGen");
//比对验证码
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;
}
Filter
Filter快速入门
FilterDemo.java核心代码
@WebFilter("/*")
public class FilterDemo implements Filter {
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
//1.放行前，对request数据进行处理
System.out.println("FilterDemo...");
//放行
filterChain.doFilter(servletRequest, servletResponse);
//2.放行后，对response数据进行处理
}
public void init(FilterConfig filterConfig) throws ServletException {
}
public void destroy() {
}
}
Filter执行流程
1.放行前，对request数据进行处理
2.放行后，对response数据进行处理
Filter使用细节
过滤器链
案例
LoginFilter.java代码
@WebFilter("/*")
public class LoginFilter implements Filter {
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
HttpServletRequest request = (HttpServletRequest) servletRequest;
//判断访问的路径是否和登录注册相关
String[] urls = { "/login.jsp", "/imgs/","/css/" ,"/loginServlet","/register.jsp","/registerServlet","/checkCodeServlet"};
//获取当前访问资源路径
String url = request.getRequestURL().toString();
for (String url1 : urls) {
if (url.contains(url1)) {
//找到了，放行
filterChain.doFilter(servletRequest, servletResponse);
return;
}
}
//1.判断session中是否有user
HttpSession session = request.getSession();
Object user = session.getAttribute("user");
//2.判断user是否为null
if (user != null) {
//登录过了
//放行
filterChain.doFilter(servletRequest, servletResponse);
}else {
//没有登录，存储提示信息，跳转登录页面
request.setAttribute("login_msg", "你尚未登录！");
request.getRequestDispatcher("/login.jsp").forward(request, servletResponse);
}
}
@Override
public void destroy() {
}
public void init(FilterConfig filterConfig) throws ServletException {
}
}
Listener
了解，现在用的并不多。
ContextLoaderListener.java代码
@WebListener
public class ContextLoaderListener implements ServletContextListener {
@Override
public void contextInitialized(ServletContextEvent servletContextEvent) {
//加载资源
System.out.println("执行了....");
}
@Override
public void contextDestroyed(ServletContextEvent servletContextEvent) {
//释放资源
}
}