用戶登錄中Cookie的簡單應用

總共分爲三個界面，第一個界面：登錄界面

<%@ page language="java" contentType="text/html; charset=utf-8" import="java.net.*"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
<h1> 用戶登錄界面</h1>
<%
             request.setCharacterEncoding("utf-8");
            String  username="";
            String password="";
            Cookie[] cookie= request.getCookies();
            if(cookie!=null&&cookie.length>0){
            	
                       for(Cookie c:cookie){
                    	   
            	if(c.getName().equals("username")){
            		
            		username=URLDecoder.decode(c.getValue(),"utf-8");       		            		
            	}
            	if(c.getName().equals("password")){
            		
            		password=URLDecoder.decode(c.getValue(), "utf-8");
            	}            	            	
            }
            }

%>
<form action="dologin.jsp"  method="post">
      <table>
            <tr>
            <td>用戶名：</td>
            <td><input type="text" name="username" value="<%=username%>"/></td>
            </tr>
            
             <tr>
              <td>密碼：</td>
            <td><input type="password" name="password" value="<%=password%>"/></td>
             </tr>
             
              <tr>
               <td colspan="2"> <input type="checkbox" name="isuseCookie" checked="checked" 
               /> 十天內免密碼登錄</td>
           
              </tr>
              
               <tr>
               <td colspan="2" align="center"><input type="submit" value="登錄"/></td>
               </tr>

      </table>
</form>

</body>
</html>

第二個界面：用戶請求處理界面

<%@page import="java.net.URLEncoder"%>
<%@ page language="java" contentType="text/html; charset=utf-8" import="java.net.*"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
<h1>用戶登錄成功</h1>

<br>
       <%
       request.setCharacterEncoding("utf-8");
       
       String[]  isuseCookie=request.getParameterValues("isuseCookie");
             if(isuseCookie!=null&&isuseCookie.length>0){
            	 //保存用戶信息到Cookie

                 //特別說明：防止中文亂碼，URLEncodeer.encode(String   "字符集");
            	 
            	 String username=URLEncoder.encode(request.getParameter("username"),"utf-8");
            	 
            	 String password=URLEncoder.encode(request.getParameter("password"),"utf-8");
            	 
            	 Cookie usernameCookie= new  Cookie("username",username);
            	 Cookie  passwordCookie= new  Cookie("password",password);
            	 //設置Cookie保存的時間，單位秒
            	 usernameCookie.setMaxAge(864000);
            	 passwordCookie.setMaxAge(864000);
            	 //添加到Cookie
            	 response.addCookie(usernameCookie);
           	 
            	 response.addCookie(passwordCookie);
             }
             else{
            	 //需要清空Cookie
            	 
            	 Cookie[] cookie =request.getCookies();
            	 if(cookie!=null&&cookie.length>0){
            		 
            		 for(Cookie c:cookie){
            			 if(c.getName().equals("username")||c.getName().equals("password")){
            				 c.setMaxAge(0);//設置Cookie失效
            				 response.addCookie(c);//重新保存Cookie
            				 
            			 }
            			 
            		 }
            		 
            	 }
            	 
            	 
            	 
            	 
             }
       
       %>
          




<br>
<br>
<a href="users.jsp">用戶信息</a>

      
      
      
      
  

</body>
</html>

第三個界面：用戶界面

<%@page import="java.net.URLDecoder"%>
<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
</head>
<body>
<h1>用戶信息輸出</h1>
<%
           String  username="";
            String password="";
            Cookie[] cookie= request.getCookies();
            if(cookie!=null&&cookie.length>0){
            	
                       for(Cookie c:cookie){
                    	   
            	if(c.getName().equals("username")){
            		
            		username= URLDecoder.decode(c.getValue(),"utf-8");         		            		
            	}
            	if(c.getName().equals("password")){
            		
            		password=URLDecoder.decode(c.getValue(), "utf-8");
            	}            	            	
            }
            }

%>
     用戶名爲：<%= username %>
     密碼：<%= password %>

</body>
</html>

可以記住用戶十天的登錄信息，十天內面密碼登錄