释放双眼，带上耳机，听听看~！
user类
package p01_user;
public class User {
private String UserName;
private String Password;
public String getUserName() {
return UserName;
}
public void setUserName(String username) {
UserName = username;
}
public String getPassword() {
return Password;
}
public void setPassword(String password) {
Password = password;
}
}登录界面（login.jsp）
<%@ page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8" import="java.util.*"%>
<html>
<head></head>
<center><h3>用户登录</h3></center>
<body style="text-align: center;">
<%--${pageContext.request.contextPath 获取项目名【其实是获取根目录资源名】} --%>
<form action="${pageContext.request.contextPath }/LoginServlet" method="post">
<table border="1" width="600px" cellpadding="0" cellspacing="0" align="center" >
<tr>
<td height="30" align="center">用户名：</td>
<td>
<input type="text" name="username" />${errorMsg }</td>
</tr>
<tr>
<td height="30" align="center">密 码：</td>
<td>
<input type="password" name="password" /></td>
</tr>
<tr>
<td height="35" align="center">自动登录时间</td>
<td>
<input type="radio" name="autologin"
value="${60*60*24*31 }" />一个月
<input type="radio" name="autologin"
value="${60*60*24*31*3 }" />三个月
<input type="radio" name="autologin"
value="${60*60*24*31*6 }" />半年
<input type="radio" name="autologin"
value="${60*60*24*31*12 }" />一年
</td>
</tr>
<tr>
<td height="30" colspan="2" align="center">
<input type="submit" value="登录" />
<input type="reset" value="重置" />
</td>
</tr>
</table>
</form>
</body>
<html>成功登录界面（index.jsp）
<%@
page language="java" contentType="text/html; charset=utf-8"
pageEncoding="utf-8" import="java.util.*"
%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<head>
<title>显示登录的用户信息</title>
</head>
<body>
<br />
<center>
<h3>欢迎光临</h3>
</center>
<br />
<br />
<c:choose>
<%--用户信息为空 --%>
<c:when test="${sessionScope.user==null }">
<a href="${pageContext.request.contextPath }/login.jsp">用户登录</a>
</c:when>
<c:otherwise>
<%--用户信息不为空 --%>
欢迎你，${sessionScope.user.getUserName()}!
<a href="${pageContext.request.contextPath }/LogoutServlet">注销</a>
</c:otherwise>
</c:choose>
<hr />
</body>
</html>信息检验
package p02_servlet;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.beanutils.BeanUtils;
import p01_user.User;
public class LoginServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
public LoginServlet() {
super();
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获取用户名和密码（从浏览器请求中获取）
String username = request.getParameter("username");
String password = request.getParameter("password");
//判断用户名和密码是否正确
if("111".equals(username)&&"222".equals(password)) {
//创建user对象来封装正确的用户信息。
User u = new User();
try {
BeanUtils.populate(u, request.getParameterMap());
}
catch(IllegalAccessException e) {
e.printStackTrace(); }
catch(InvocationTargetException e) {
e.printStackTrace(); }
/*
* u.setUserName(username); u.setPassword(password);
*/
//放到域对象中去，为了后面方便调用信息
request.getSession().setAttribute("user", u);
//获取用户是否点击了自动登录的标识符
String autoLogin = request.getParameter("autologin");
if(autoLogin!=null) {
//说明用户点击了自动登录，这时候就要把信息保存到cookie中去
Cookie c = new Cookie("autologin", username+"_"+password);
int auto_save_time = Integer.parseInt(autoLogin);
c.setMaxAge(auto_save_time);
//设置路径，可以省略
c.setPath(request.getContextPath());
//响应到浏览器
response.addCookie(c);
}
//重定向到主页面.getcontextPath是获取项目名称【站点目录名称】
response.sendRedirect(request.getContextPath()+"/index.jsp");
}else {
//登陆失败了
request.setAttribute("errorMsg", "用户名或密码错误");
RequestDispatcher rd = request.getRequestDispatcher("/login.jsp");
rd.forward(request, response);
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}过滤cookie实现自动登录
package p03_Filter;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import p01_user.User;
/**
* Servlet Filter implementation class AutoLoginFilter
*/
public class AutoLoginFilter implements Filter {
public AutoLoginFilter() {
}
public void destroy() {
}
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
//1,获取所有的cookie,在ServletRequest中没有获取所有cookie的方法
HttpServletRequest req = (HttpServletRequest)request;
Cookie[] cs = req.getCookies();
//遍历cookie，找到自动登录的cookie
String autologin = null;//cookie名称
String user_massage = null;//保存在cookie中的用户信息
for(int i = 0 ;cs!=null&&i<cs.length;i++) {
String cookie_name = cs[i].getName();
if("autologin".equals(cookie_name)) {
user_massage = cs[i].getValue();
}
}
if(user_massage!=null) {
String[] msg = user_massage.split("_");
String user_name = msg[0];
String user_password = msg[1];
if("111".equals(user_name)&&"222".equals(user_password)) {
//创建user对象来封装正确的用户信息。
User u = new User();
u.setUserName(user_name);
u.setPassword(user_password);
//放到域对象中去，为了后面方便调用信息
req.getSession().setAttribute("user", u);
}
}
chain.doFilter(request, response);
}
/**
* @see Filter#init(FilterConfig)
*/
public void init(FilterConfig fConfig) throws ServletException {
// TODO Auto-generated method stub
}
}登出
package p02_servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* Servlet implementation class LogoutServlet
*/
public class LogoutServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public LogoutServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//清除session保存的用户信息
request.getSession().removeAttribute("user");
//清除cookie,就是创建同名的cookie
Cookie c = new Cookie("autoLogin", "");
c.setMaxAge(0);//0就是立马销毁
c.setPath(request.getContextPath());
response.addCookie(c);
//重定向到主页面
response.sendRedirect(request.getContextPath()+"/index.jsp");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}