Java Web servlet与cookie

先来看看效果图：

点击submit后：

点击查看Cookies：

在C:\Documents and Settings\Administrator\Cookies目录下面会有一个 hongten@webproject_cookie[2].txt 的文件；

这就是cookie的文件；

再来看看代码是怎样实现的：

cookiesInput.html

代码：

<html>
<head>
<title>cookie input page</title>
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
</head>
<body>
请输入用户名（英文或者数字）<br>
<form name="form1" action="SetCookiesServlet" method="post" >
<table border="0">
<tr><td>用户名：</td>
<td><input type="text" name="username">
</td></tr>
<tr><td colspan="2" align="center">
<input name="submit" value="submit" type="submit">
</td></tr>
</table>
</form>
</body>
</html>

SetCookiesServlet.java

代码：

/**
*
*/
package webbook.chapter6;

import java.io.IOException;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
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;

import webbook.util.StringUtil;

/**
*
* @author XHW
*
* @date 2011-7-22
*
*/
public class SetCookiesServlet extends HttpServlet {

private static final long serialVersionUID = 6849802930688070121L;

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  String output = null;
  String username = request.getParameter("username");
  if (!StringUtil.validateNull(username)) {
   Cookie cookie1 = new Cookie("username", StringUtil
     .filterHtml(username));
   // cookie的有效期为1个月
   cookie1.setMaxAge(24 * 60 * 60 * 30);
   SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
   Cookie cookie2 = new Cookie("lastTime", sdf.format(new Date()));
   cookie2.setMaxAge(24 * 60 * 60 * 30);
   response.addCookie(cookie1);
   response.addCookie(cookie2);
   output = "本次登录时间与用户名已经写到Cookie中。<br><a href=\"/webproject_cookie/GetCookiesServlet\">查看Cookies</a>";
  } else {
   output = "用户名为空，请重新输入。<br><a herf=\"/webproject_cookie/cookieInput.htm\">输入用户名</a>";
  }

  response.setContentType("text/html;charset=UTF-8");
  PrintWriter out = response.getWriter();
  out.println("<html>");
  out.println("<head><title>set cookies </title></head>");
  out.println("<body>");
  out.println("<h2>" + output + "</h2>");
  out.println("</body>");
  out.println("</html>");
  out.flush();
  out.close();
}
}

GetCookiesServlet.java

代码：

/**
*
*/
package webbook.chapter6;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
*
* @author XHW
*
* @date 2011-7-22
*
*/
public class GetCookiesServlet extends HttpServlet {

private static final long serialVersionUID = -156960358689563625L;

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  response.setContentType("text/html;charset=UTF-8");
  PrintWriter out = response.getWriter();
  out.println("<html>");
  out.println("<head><title>display login infomation</title></head>");
  out.println("<body>");
  out.println("<h2>从Cookie中获得上次登录时间与用户名</h2>");

//获取所有的cookie值

  Cookie[] cookies = request.getCookies();
  Cookie cookie = null;
  for (int i = 0; i < cookies.length; i++) {
   cookie = cookies[i];
   if (cookie.getName().equals("username")) {
    out.println("用户名：" + cookie.getValue());
    out.println("<br>");
   }
   if (cookie.getName().equals("lastTime")) {
    out.println("上次登录时间：" + cookie.getValue());
    out.println("<br>");
   }
  }
  out.println("</body>");
  out.println("</html>");
  out.flush();
  out.close();
}
}

cookie是web服务器通过浏览器保存在www用户端硬盘上的一个文本文件，这个文件中包含了文本信息

文本信息的内容是以“名/值”对（key/value）的形式进行储存的

可以让web开发者通过程序读写这个文本文件

在Windows XP中保存Cookie的目录是：C:\Documents and Settings\用户名\Cookies

Cookie的作用：

　　解决浏览器用户与web服务器之间无状态通信

使用cookie的时候注意的事项：

　　cookie的大小和数量是有限制的

　　cookie在个人硬盘上所保存的文本信息是以明文格式进行保存的，没有任何的加密措施

　　浏览器可以设定不使用cookie

posted @ 2011-07-22 22:22 Hongten 阅读(4772) 评论(1) 编辑收藏举报

会员力量，点亮园子希望

刷新页面返回顶部

Java Web servlet与cookie

公告