Servlet实现Cookie的创建，读取，删除

（1）如何创建cookie案例

（1）如何创建cookie案例

[java] view plain copy

1. package com.tsinghua;  
2.   
3.   
4. import javax.servlet.http.*;  
5. import java.io.*;  
6.   
7. public class CookieTest1 extends HttpServlet{  
8.       
9.     //处理get请求  
10.       
11.     public void doGet(HttpServletRequest req,HttpServletResponse res){  
12.           
13.         try {  
14.               
15.             res.setContentType("text/html;charset=gbk");  
16.             PrintWriter pw=res.getWriter();  
17.             //当用户访问该servlet时， 就将信息创建到该用户的cookie中  
18.           
19.             //1. 现在服务器端创建一个cookie  
20.             Cookie myCookie=new Cookie("color1","red");  
21.               
22.             //2. 该cookie存在的时间 以秒为单位  
23.             myCookie.setMaxAge(30000);  
24.             //如果你不设置存在时间,那么该cookie将不会保存  
25.               
26.             //3. 将该cookie写回到客户端  
27.             res.addCookie(myCookie);  
28.               
29.             pw.println("已经创建了cookie");  
30.         }  
31.         catch (Exception ex) {  
32.               
33.             ex.printStackTrace();  
34.         }                 
35.     }  
36. }  

（2）如何读取cookie案例

[java] view plain copy

1. package com.tsinghua;  
2.   
3. import javax.servlet.http.*;  
4. import java.io.*;  
5.   
6. public class CookieTest2 extends HttpServlet{  
7.       
8.     //处理get请求  
9.       
10.     public void doGet(HttpServletRequest req,HttpServletResponse res){  
11.           
12.           
13.         try {  
14.               
15.             res.setContentType("text/html;charset=gbk");  
16.           
17.             PrintWriter pw=res.getWriter();  
18.           
19.             //从客户端得到所有cookie信息  
20.             Cookie [] allCookies=req.getCookies();  
21.           
22.             int i=0;  
23.             //如果allCookies不为空...  
24.             if(allCookies!=null){  
25.               
26.                 //从中取出cookie  
27.                 for(i=0;i<allCookies.length;i++){  
28.                   
29.                     //依次取出  
30.                     Cookie temp=allCookies[i];  
31.                   
32.                     if(temp.getName().equals("color1")){  
33.                           
34.                         //得到cookie的值  
35.                         String val=temp.getValue();  
36.                           
37.                         pw.println ("color1="+val);  
38.                         break;  
39.                           
40.                     }  
41.                 }  
42.                 if(allCookies.length==i){  
43.                       
44.                     pw.println("cookie 过期");  
45.                 }  
46.                           
47.             }else{            
48.                 pw.println ("不存在color1这个cookie/或是过期了!");  
49.             }     
50.           
51.         }  
52.         catch (Exception ex) {  
53.               
54.             ex.printStackTrace();  
55.         }  
56.   
57.     }  
58. }  

（3）如何删除cookie案例

[java] view plain copy

1. package com.tsinghua;  
2.   
3.   
4. import javax.servlet.http.*;  
5. import java.io.*;  
6.   
7. public class CookieTest3 extends HttpServlet{  
8.       
9.     //处理get请求  
10.       
11.     public void doGet(HttpServletRequest req,HttpServletResponse res){  
12.           
13.           
14.         try {  
15.               
16.   
17.             res.setContentType("text/html;charset=gbk");  
18.           
19.             PrintWriter pw=res.getWriter();  
20.           
21.             //从客户端得到所有cookie信息  
22.             Cookie [] allCookies=req.getCookies();  
23.           
24.             int i=0;  
25.             //如果allCookies不为空...  
26.             if(allCookies!=null){  
27.               
28.                 //从中取出cookie  
29.                 for(i=0;i<allCookies.length;i++){  
30.                   
31.                     //依次取出  
32.                     Cookie temp=allCookies[i];  
33.                   
34.                     if(temp.getName().equals("color")){  
35.                           
36.                         //将该cookie删除  
37.                         temp.setMaxAge(0);  
38.                         pw.println("删除了color这个cookie");  
39.                         break;  
40.                           
41.                     }  
42.                 }         
43.               
44.             }     
45.           
46.         }  
47.         catch (Exception ex) {  
48.               
49.             ex.printStackTrace();  
50.         }  
51.   
52.     }  
53. }  

（2）如何读取cookie案例

[java] view plain copy

1. package com.tsinghua;  
2.   
3. import javax.servlet.http.*;  
4. import java.io.*;  
5.   
6. public class CookieTest2 extends HttpServlet{  
7.       
8.     //处理get请求  
9.       
10.     public void doGet(HttpServletRequest req,HttpServletResponse res){  
11.           
12.           
13.         try {  
14.               
15.             res.setContentType("text/html;charset=gbk");  
16.           
17.             PrintWriter pw=res.getWriter();  
18.           
19.             //从客户端得到所有cookie信息  
20.             Cookie [] allCookies=req.getCookies();  
21.           
22.             int i=0;  
23.             //如果allCookies不为空...  
24.             if(allCookies!=null){  
25.               
26.                 //从中取出cookie  
27.                 for(i=0;i<allCookies.length;i++){  
28.                   
29.                     //依次取出  
30.                     Cookie temp=allCookies[i];  
31.                   
32.                     if(temp.getName().equals("color1")){  
33.                           
34.                         //得到cookie的值  
35.                         String val=temp.getValue();  
36.                           
37.                         pw.println ("color1="+val);  
38.                         break;  
39.                           
40.                     }  
41.                 }  
42.                 if(allCookies.length==i){  
43.                       
44.                     pw.println("cookie 过期");  
45.                 }  
46.                           
47.             }else{            
48.                 pw.println ("不存在color1这个cookie/或是过期了!");  
49.             }     
50.           
51.         }  
52.         catch (Exception ex) {  
53.               
54.             ex.printStackTrace();  
55.         }  
56.   
57.     }  
58. }  

（3）如何删除cookie案例

[java] view plain copy

1. package com.tsinghua;  
2.   
3.   
4. import javax.servlet.http.*;  
5. import java.io.*;  
6.   
7. public class CookieTest3 extends HttpServlet{  
8.       
9.     //处理get请求  
10.       
11.     public void doGet(HttpServletRequest req,HttpServletResponse res){  
12.           
13.           
14.         try {  
15.               
16.   
17.             res.setContentType("text/html;charset=gbk");  
18.           
19.             PrintWriter pw=res.getWriter();  
20.           
21.             //从客户端得到所有cookie信息  
22.             Cookie [] allCookies=req.getCookies();  
23.           
24.             int i=0;  
25.             //如果allCookies不为空...  
26.             if(allCookies!=null){  
27.               
28.                 //从中取出cookie  
29.                 for(i=0;i<allCookies.length;i++){  
30.                   
31.                     //依次取出  
32.                     Cookie temp=allCookies[i];  
33.                   
34.                     if(temp.getName().equals("color")){  
35.                           
36.                         //将该cookie删除  
37.                         temp.setMaxAge(0);  
38.                         pw.println("删除了color这个cookie");  
39.                         break;  
40.                           
41.                     }  
42.                 }         
43.               
44.             }     
45.           
46.         }  
47.         catch (Exception ex) {  
48.               
49.             ex.printStackTrace();  
50.         }  
51.   
52.     }  
53. }