注意：過濾器主要過濾request,response裡面的值。

*web.xml----

*登入action新增cookie-------

*filter過濾器獲取cookie------

（不用從新輸入使用者名稱，密碼，直接讀取cookie通過查詢資料庫，獲取User  user ，

           request.getSession().setAttribute("user",user1)）

*其他action裡面獲取---------

        (DUser user=(DUser) request.getSession().getAttribute("user");//)自動登入

*登出：刪除cookie----------

1、web配置檔案--過濾所有請求

<filter>
  <filter-name>LoginFilter</filter-name>
  <filter-class>com.djh.listener.LoginFilter</filter-class>
 </filter>
 <filter-mapping>
  <filter-name>LoginFilter</filter-name>
  <url-pattern>/*</url-pattern>
 </filter-mapping>

 

2、登入的action裡面新增cookie

session.setAttribute("user", user);
      Cookie cookie1 = new Cookie("username",user.getUPhoneNum());  
               Cookie cookie2 = new Cookie("password",user.getUPassword());
//               Cookie cookie3 = new Cookie("SESSIONID","----");
               
               cookie1.setMaxAge(60 * 60);  
               cookie2.setMaxAge(60 * 60); 
//               cookie3.setMaxAge(0); 
               
               
               cookie1.setPath("/");  
               cookie2.setPath("/");  
//               cookie3.setPath("/");  
                 
               response.addCookie(cookie1);  
               response.addCookie(cookie2);  
 

3、過濾器類LoginFilter--主要方法是doFilter，在此方法裡取出request.getCcookies()值，set到request.getSession().setAttribute("user",user1); 
，其他介面通過過濾器set過來的“user”值取出uname,password自動登入。

package com.djh.listener;

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 javax.servlet.http.HttpServletResponse;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.djh.entity.DUser;
import com.djh.service.LoginService;
import com.djh.util.MD5;

/**
 * @author shenpai
 * 實現使用者自動登入的過濾器
 */
public class LoginFilter implements Filter {
 ApplicationContext context = new ClassPathXmlApplicationContext(new String[]{"applicationContext-*.xml"}); 
 LoginService loginService=(LoginService) context.getBean("loginService");//獲取UserService的bean的例項
  
 public void destroy() {
 }
 
 public void doFilter(ServletRequest req, ServletResponse resp,
   FilterChain chain) throws IOException, ServletException {
  try {
   
//   System.out.println("----------------");
   //把ServletRequest和ServletResponse轉換成HttpServletRequest和HttpServletResponse的型別
   HttpServletRequest request=(HttpServletRequest) req;
   HttpServletResponse response = (HttpServletResponse) resp ;
   //首先檢查使用者是否登入
   DUser user=(DUser) request.getSession().getAttribute("user");// 
   if(user!=null){
    chain.doFilter(request, response);
    return;
   }
   //檢查使用者是否帶來cookie
   String username= null;
   String password =null;
   Cookie[] cookies=request.getCookies();
   for(int i=0;cookies!=null && i<cookies.length;i++){  
//    System.out.println(cookies[i].getName()+cookies[i].getValue()+"----過濾器獲取cookies---");
             if(cookies[i].getName().equals("username")){  
                 username = cookies[i].getValue();  
             }  
             if(cookies[i].getName().equals("password")){  
                 password = cookies[i].getValue();  
             }  
         } 
   
    if(username==null || password==null){//使用者沒有帶來cookie  
              chain.doFilter(req, resp);  
              return;  
         }
   //使用者帶來了cookie   
    DUser user1 = loginService.findUserByPhoneNumAndPassword(
      username, password);  
         String save_password = user1.getUPassword();  
         if(!password.equals(save_password)){  
             chain.doFilter(req, resp);  
             return;  
         }  
         request.getSession().setAttribute("user",user1);  //通過requsest放到相關需要登入資訊的action裡面，action裡面通過reqest.獲取使用者資訊，實現自動登入。
         chain.doFilter(req, resp);
         return; 
  } catch (Exception e) {
   e.printStackTrace();
  } 
 }

 public void init(FilterConfig arg0) throws ServletException {
 }
 

}

4、Action獲取使用者資訊，實現自動登入。

DUser user=(DUser) session.getAttribute("user");//獲取登入使用者物件

5、登出：刪除cookie

// 使用者登出
 public String logout() {
            HttpSession session = request.getSession(false);
            if (session != null)
            session.removeAttribute("user");
            Cookie cookie = cookieUtils.<span style="BACKGROUND-COLOR: #3333ff">delCookie</span>(request);
            if (cookie != null)
                    response.addCookie(cookie);
            return "login";
 }

private CookieUtils cookieUtils = new CookieUtils();

// 刪除cookie
 public Cookie <span style="color:#3333ff;">delCookie</span>(HttpServletRequest request) {
         Cookie[] cookies = request.getCookies();
         if (cookies != null) {
                  for (Cookie cookie : cookies) {
                         if ("username".equals(cookie.getName())) {
                                cookie.setValue("");
                                cookie.setMaxAge(0);
                          }else if("password".equals(cookie.getName())){
                                cookie.setValue("");
                                cookie.setMaxAge(0);
                         }
                         return cookie;
                 }
         }
         return null;
 }