深入体验JavaWeb开发内幕——由创建Cookie到Cookie的简单应用

[java]
<pre name="code" class="java">MakeCookie .java</pre> 
package net.csdn.cookie;import java.io.IOException; 
import java.io.PrintWriter;import java.util.Date; 
import javax.servlet.ServletException;import javax.servlet.http.Cookie; 
import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
public class MakeCookie extends HttpServlet 
{ 
public void doGet(HttpServletRequest request, HttpServletResponse response) 
throws ServletException, IOException { 
makeCookie(response);}private void makeCookie(HttpServletResponse response) 
throws IOException { 
//为客户端指定显示编码 
response.setContentType("text/html;charset=utf-8");PrintWriter out = response.getWriter(); 
//创建一个Cookie实例名字为"username",值为"lijizh1013"Cookie cookie = new Cookie("username","lijizh1013"); 
//为Cookie设置存活时间，默认的为到该浏览器关闭 
cookie.setMaxAge(24*3600); 
//为Cookie设置路径 
cookie.setPath("/Cookie/MakeCookie"); 
//向浏览器写入Cookie 
response.addCookie(cookie);out.println("Cookie已经写入到客户端！"); 
} 
public void doPost(HttpServletRequest request, HttpServletResponse response 
)throws ServletException, IOException {doGet(request, response);}}
<pre></pre>
效果：
在浏览器发送请求前没有任何cookie文件
<img src=/2012/1030/20121030100654484.png" alt="" height="112" width="734">
发送请求后：
<img src=/2012/1030/20121030100654100.png" alt="">
<img src=/2012/1030/20121030100654917.png" alt="">
获取Cookie的值：

<pre name="code" class="java">getCookie(request, response);</pre> 
具体如下：


<pre name="code" class="java">private void getCookie(HttpServletRequest request,
 HttpServletResponse response) throws IOException {
 为浏览器设置显示编码
 response.setContentType("text/html;charset=utf-8");
 PrintWriter out = response.getWriter();
 //通过 request.getCookies()返回一个Cookie数组对数组进行遍历得到具体的Cookie后，通过Cookie对象的getName()和getValue()方法得到Cookie的
 //名和值
 Cookie [] cookies = request.getCookies();
 for(int i=0;cookies!=null && i<cookies.length;i++){
 String cname = cookies[i].getName();
 String cvalue = cookies[i].getValue();
 out.println("获取Cookie"+cname+"——"+cvalue);
 }</pre>效果如图：

<img src=/2012/1030/20121030100654152.png" alt="">
一个关于获取用户访问时间的实例：

<pre name="code" class="java">response.setContentType("text/html;charset=utf-8");
 PrintWriter out = response.getWriter();
 out.println("你上次访问的时间是：");
 Cookie [] cookies = request.getCookies();
 for(int i=0;cookies!=null && i<cookies.length;i++){
 if(cookies[i].getName().equals("LastAccessName")){
 long time = Long.valueOf(cookies[i].getValue());
 Date date = new Date (time);
 out.println(date.toLocaleString());
 }


 }
 Cookie cok = new Cookie("LastAccessName",System.currentTimeMillis()+"");
 cok.setMaxAge(1*3600);
 response.addCookie(cok);</pre> 
效果如图：

当用户第一访问时：
<img src=/2012/1030/20121030100654315.png" alt="">
下一次再访问时：
<img src=/2012/1030/20121030100654606.png" alt="">
再次访问时：
<img src=/2012/1030/20121030100654284.png" alt="">
这样就可以通过Cookie得知浏览器上次访问的时间了,赶快自己试一试吧！ 

 
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补充：Web开发 , 其他 ,