java cookie实现自动登录

登录界面：login.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>







  

	账号：

	密码：

		 自动登录

		
  

登录servlet：LoginServlet.java

package com.itheima.servlet;

import java.io.IOException;
import java.sql.SQLException;

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 com.itheima.dao.UserDao;
import com.itheima.dao.impl.UserDaoImpl;
import com.itheima.domain.UserBean;

/**
 * Servlet implementation class LoginServlet
 */
public class LoginServlet extends HttpServlet {
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

		try {
			String userName = request.getParameter("username");
			String password = request.getParameter("password");
			String autoLogin = request.getParameter("auto_login");
			UserBean user = new UserBean();
			user.setUsername(userName);
			user.setPassword(password);
			
			UserDao dao = new UserDaoImpl();
			UserBean userBean = dao.login(user);
			
			if(userBean != null){
				
				//页面提交上来的时候，是否选择了自动登录
				if("on".equals(autoLogin)){
					
					//发送cookie给客户端
					
					Cookie cookie = new Cookie("auto_login", userName+"#itheima#"+password);
					cookie.setMaxAge(60*60*24*7);//7天有效期
					cookie.setPath("/AutoLoginDemo");
					//cookie.setPath(request.getContextPath());
					response.addCookie(cookie);
					
				}
				
				
				//成功了，进入首页
				request.getSession().setAttribute("userBean", userBean);
				response.sendRedirect("index.jsp");
			}else{
				//不成功...
				request.getRequestDispatcher("login.jsp").forward(request, response);
			}
			
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

过滤器：AutoLoginFilter.java

package com.itheima.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.HttpServletRequest;

import com.itheima.dao.UserDao;
import com.itheima.dao.impl.UserDaoImpl;
import com.itheima.domain.UserBean;
import com.itheima.util.CookieUtil;

/**
 * Servlet Filter implementation class AutoLoginFilter
 */
public class AutoLoginFilter implements Filter {

	/**
	 * @see Filter#destroy()
	 */
	public void destroy() {
		// TODO Auto-generated method stub
	}

	/**
	 * @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
	 */
	public void doFilter(ServletRequest req, ServletResponse response, FilterChain chain) throws IOException, ServletException {

		try {
			HttpServletRequest request = (HttpServletRequest) req;
			
			//先判断，现在session中还有没有那个userBean.
			UserBean userBean = (UserBean) request.getSession().getAttribute("userBean");
			//还有，有效。
			if(userBean != null){
				chain.doFilter(request, response);
			}else{
				//代表session失效了。
				
				//2. 看cookie。
				
				//1. 来请求的时候，先从请求里面取出cookie , 但是cookie有很多的key-value
				Cookie[] cookies = request.getCookies();
				//2. 从一堆的cookie里面找出我们以前给浏览器发的那个cookie
				Cookie cookie = CookieUtil.findCookie(cookies, "auto_login");
				
				//第一次来
				if(cookie  == null){
					chain.doFilter(request, response);
				}else{
					
					//不是第一次。
					
					String value = cookie.getValue();
					String username = value.split("#itheima#")[0];
					String password = value.split("#itheima#")[1];

					//完成登录
					UserBean user = new UserBean();
					user.setUsername(username);
					user.setPassword(password);

					UserDao dao = new UserDaoImpl();
					userBean = dao.login(user);
					
					//使用session存这个值到域中，方便下一次未过期前还可以用。
					request.getSession().setAttribute("userBean", userBean);
					
					chain.doFilter(request, response);
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
			chain.doFilter(req, response);
		}
	}

	
	/**
	 * @see Filter#init(FilterConfig)
	 */
	public void init(FilterConfig fConfig) throws ServletException {
//		有可能在这里面执行10分钟的耗时
	}

}

判断cookie是否为空的工具类：findCookie.java

package com.itheima.util;

import javax.servlet.http.Cookie;

public class CookieUtil {

//	Cookie: JSESSIONID=373D65E0C30C5E3BB327D8ED538FFE5E; auto_login=itheima#itheima#10010
	public static Cookie findCookie(Cookie [] cookies , String name){
		if(cookies != null){
			for (Cookie cookie : cookies) {
				if(name.equals(cookie.getName())){
					return cookie;
				}
			}
		}
		return null;
	}
}

web.xml

  AutoLoginDemo
  
    index.html
    index.htm
    index.jsp
    default.html
    default.htm
    default.jsp
  
  
    
    LoginServlet
    LoginServlet
    com.itheima.servlet.LoginServlet
  
  
    LoginServlet
    /LoginServlet
  
  
    AutoLoginFilter
    AutoLoginFilter
    com.itheima.filter.AutoLoginFilter
  
  
    AutoLoginFilter
    /*