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Servlet实现Cookie的创建,读取,删除

2016-09-12 12:45 239 查看
(1)如何创建cookie案例

(1)如何创建cookie案例

[java]
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package com.tsinghua;  
  
  
import javax.servlet.http.*;  
import java.io.*;  
  
public class CookieTest1 extends HttpServlet{  
      
    //处理get请求  
      
    public void doGet(HttpServletRequest req,HttpServletResponse res){  
          
        try {  
              
            res.setContentType("text/html;charset=gbk");  
            PrintWriter pw=res.getWriter();  
            //当用户访问该servlet时, 就将信息创建到该用户的cookie中  
          
            //1. 现在服务器端创建一个cookie  
            Cookie myCookie=new Cookie("color1","red");  
              
            //2. 该cookie存在的时间 以秒为单位  
            myCookie.setMaxAge(30000);  
            //如果你不设置存在时间,那么该cookie将不会保存  
              
            //3. 将该cookie写回到客户端  
            res.addCookie(myCookie);  
              
            pw.println("已经创建了cookie");  
        }  
        catch (Exception ex) {  
              
            ex.printStackTrace();  
        }                 
    }  
}  

(2)如何读取cookie案例

[java]
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package com.tsinghua;  
  
import javax.servlet.http.*;  
import java.io.*;  
  
public class CookieTest2 extends HttpServlet{  
      
    //处理get请求  
      
    public void doGet(HttpServletRequest req,HttpServletResponse res){  
          
          
        try {  
              
            res.setContentType("text/html;charset=gbk");  
          
            PrintWriter pw=res.getWriter();  
          
            //从客户端得到所有cookie信息  
            Cookie [] allCookies=req.getCookies();  
          
            int i=0;  
            //如果allCookies不为空...  
            if(allCookies!=null){  
              
                //从中取出cookie  
                for(i=0;i<allCookies.length;i++){  
                  
                    //依次取出  
                    Cookie temp=allCookies[i];  
                  
                    if(temp.getName().equals("color1")){  
                          
                        //得到cookie的值  
                        String val=temp.getValue();  
                          
                        pw.println ("color1="+val);  
                        break;  
                          
                    }  
                }  
                if(allCookies.length==i){  
                      
                    pw.println("cookie 过期");  
                }  
                          
            }else{            
                pw.println ("不存在color1这个cookie/或是过期了!");  
            }     
          
        }  
        catch (Exception ex) {  
              
            ex.printStackTrace();  
        }  
  
    }  
}  

(3)如何删除cookie案例

[java]
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package com.tsinghua;  
  
  
import javax.servlet.http.*;  
import java.io.*;  
  
public class CookieTest3 extends HttpServlet{  
      
    //处理get请求  
      
    public void doGet(HttpServletRequest req,HttpServletResponse res){  
          
          
        try {  
              
  
            res.setContentType("text/html;charset=gbk");  
          
            PrintWriter pw=res.getWriter();  
          
            //从客户端得到所有cookie信息  
            Cookie [] allCookies=req.getCookies();  
          
            int i=0;  
            //如果allCookies不为空...  
            if(allCookies!=null){  
              
                //从中取出cookie  
                for(i=0;i<allCookies.length;i++){  
                  
                    //依次取出  
                    Cookie temp=allCookies[i];  
                  
                    if(temp.getName().equals("color")){  
                          
                        //将该cookie删除  
                        temp.setMaxAge(0);  
                        pw.println("删除了color这个cookie");  
                        break;  
                          
                    }  
                }         
              
            }     
          
        }  
        catch (Exception ex) {  
              
            ex.printStackTrace();  
        }  
  
    }  
}  

(2)如何读取cookie案例

[java]
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package com.tsinghua;  
  
import javax.servlet.http.*;  
import java.io.*;  
  
public class CookieTest2 extends HttpServlet{  
      
    //处理get请求  
      
    public void doGet(HttpServletRequest req,HttpServletResponse res){  
          
          
        try {  
              
            res.setContentType("text/html;charset=gbk");  
          
            PrintWriter pw=res.getWriter();  
          
            //从客户端得到所有cookie信息  
            Cookie [] allCookies=req.getCookies();  
          
            int i=0;  
            //如果allCookies不为空...  
            if(allCookies!=null){  
              
                //从中取出cookie  
                for(i=0;i<allCookies.length;i++){  
                  
                    //依次取出  
                    Cookie temp=allCookies[i];  
                  
                    if(temp.getName().equals("color1")){  
                          
                        //得到cookie的值  
                        String val=temp.getValue();  
                          
                        pw.println ("color1="+val);  
                        break;  
                          
                    }  
                }  
                if(allCookies.length==i){  
                      
                    pw.println("cookie 过期");  
                }  
                          
            }else{            
                pw.println ("不存在color1这个cookie/或是过期了!");  
            }     
          
        }  
        catch (Exception ex) {  
              
            ex.printStackTrace();  
        }  
  
    }  
}  

(3)如何删除cookie案例

[java]
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package com.tsinghua;  
  
  
import javax.servlet.http.*;  
import java.io.*;  
  
public class CookieTest3 extends HttpServlet{  
      
    //处理get请求  
      
    public void doGet(HttpServletRequest req,HttpServletResponse res){  
          
          
        try {  
              
  
            res.setContentType("text/html;charset=gbk");  
          
            PrintWriter pw=res.getWriter();  
          
            //从客户端得到所有cookie信息  
            Cookie [] allCookies=req.getCookies();  
          
            int i=0;  
            //如果allCookies不为空...  
            if(allCookies!=null){  
              
                //从中取出cookie  
                for(i=0;
a7d7
i<allCookies.length;i++){  
                  
                    //依次取出  
                    Cookie temp=allCookies[i];  
                  
                    if(temp.getName().equals("color")){  
                          
                        //将该cookie删除  
                        temp.setMaxAge(0);  
                        pw.println("删除了color这个cookie");  
                        break;  
                          
                    }  
                }         
              
            }     
          
        }  
        catch (Exception ex) {  
              
            ex.printStackTrace();  
        }  
  
    }  
}  
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