案例：Cookie在登录中的应用

 

URL编码与解码的工具类解决中文乱码的问题，这个工具类在java.net.*包里

编码：URLEncoder.encode(String s,String enc)//s：对哪个字符串进行编码，enc：用的字符集（例：utf-8）

解码：URLDecoder.decode(String s,String enc)//s：对哪个字符串进行解码，enc：用哪个字符集解码（例：utf-8）

login.jsp

1 <%@ page language="java" import="java.util.*,java.net.*" contentType="text/html; charset=utf-8"%> 2 <% 3 String path = request.getContextPath(); 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 5 %> 6  7  8  9   10     11     12     13     
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用户登录
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26     <% 27       request.setCharacterEncoding("utf-8");28       String username="";29       String password = "";30       Cookie[] cookies = request.getCookies();31       if(cookies!=null&&cookies.length>0)32       {33            for(Cookie c:cookies)34            {35               if(c.getName().equals("username"))36               {37                    username =  URLDecoder.decode(c.getValue(),"utf-8");38               }39               if(c.getName().equals("password"))40               {41                    password =  URLDecoder.decode(c.getValue(),"utf-8");42               }43            }44       }45     %>46     
     
      47        
      
       48          
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51          
52          
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55          
56          
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61          
62        
       
        
         
用户名：
         
        
        
         
密码：
         
        
        
         
十天内记住我的登录状态
        
        
         
        
       
      
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64   65 

dologin.jsp

1 <%@ page language="java" import="java.util.*,java.net.*" contentType="text/html; charset=utf-8"%> 2 <% 3 String path = request.getContextPath(); 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 5 %> 6  7  8  9   10     11     12     13     14     
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登录成功
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28     
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31     <% 32        request.setCharacterEncoding("utf-8");33        //首先判断用户是否选择了记住登录状态34        String[] isUseCookies = request.getParameterValues("isUseCookie");35        if(isUseCookies!=null&&isUseCookies.length>0)36        {37           //把用户名和密码保存在Cookie对象里面。38           String username = URLEncoder.encode(request.getParameter("username"),"utf-8");39           //使用URLEncoder解决无法在Cookie当中保存中文字符串问题40           String password = URLEncoder.encode(request.getParameter("password"),"utf-8");41           42           Cookie usernameCookie = new Cookie("username",username);43           Cookie passwordCookie = new Cookie("password",password);44           usernameCookie.setMaxAge(864000);45           passwordCookie.setMaxAge(864000);//设置最大生存期限为10天46           response.addCookie(usernameCookie);47           response.addCookie(passwordCookie);48        }49        else50        {
    //如果用户没有勾选记住用户名、密码的复选框，则把已经保存的原来的cookie设置失效51           Cookie[] cookies = request.getCookies();52        //曾经保存过用户名、密码53           if(cookies!=null&&cookies.length>0)54           {55              for(Cookie c:cookies)56              {57                 if(c.getName().equals("username")||c.getName().equals("password"))58                 {59                     c.setMaxAge(0); //设置Cookie失效60                     response.addCookie(c); //重新保存。61                 }62              }63           }64        }65     %>66     查看用户信息67     68   69 

user.jsp

1 <%@ page language="java" import="java.util.*,java.net.*" contentType="text/html; charset=utf-8"%> 2 <% 3 String path = request.getContextPath(); 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 5 %> 6  7  8  9   10     11     12     13     14     
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用户信息
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28     <% 29       request.setCharacterEncoding("utf-8");30       String username="";31       String password = "";32       Cookie[] cookies = request.getCookies();33       if(cookies!=null&&cookies.length>0)34       {35            for(Cookie c:cookies)36            {37               if(c.getName().equals("username"))38               {39                    username = URLDecoder.decode(c.getValue(),"utf-8");40               }41               if(c.getName().equals("password"))42               {43                    password = URLDecoder.decode(c.getValue(),"utf-8");44               }45            }46       }47     %>48     
49     
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51          用户名：<%=username %>
52          密码：<%=password %>
53   54