Java web 简单是cookie、session、application使用

最新推荐文章于 2022-04-05 21:52:45 发布

小风_2014

最新推荐文章于 2022-04-05 21:52:45 发布

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本文链接：https://blog.youkuaiyun.com/hege3706/article/details/38875253

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jsp页面

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%
	Cookie[] cookies=request.getCookies();
	String uname="";
	
	if(cookies!=null){
		for(Cookie c :cookies){
			if(c.getName().equals("myCookie")){
				uname=c.getValue();
				
			}
		}
	}
 %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'login.jsp' starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

  </head>
  
  <body>
      <form action="/MVCDemo/servlet/LoginServlet" method="post"> 
   	用户名：<input name="uname" type="text" value="<%=uname %>"><br/>
   	密码：<input name="upwd" type="password"/><br/>
   	<input type="submit" value="登陆"/>
   
  </body>
</html>

servlet页面

package com.neusoft.controller;

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

import javax.servlet.ServletContext;
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 javax.servlet.http.HttpSession;

public class LoginServlet extends HttpServlet {

	/**
	 * The doGet method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to get.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		String uname=request.getParameter("uname");
		
		String upwd=request.getParameter("upwd");
		
		if(uname.equals("zhangsan")&&upwd.equals("123")){
			ServletContext application=this.getServletContext();
			HttpSession session=request.getSession();
			
			
			Cookie c=new Cookie("myCookie",uname);
			c.setMaxAge(3600);
			c.setPath("/");
			response.addCookie(c);
			
			//作用域不同
			//request在相同的请求中有效
			//session在同一次回话中有效
			
			if(application.getAttribute("count")!=null){
				Integer count=(Integer)application.getAttribute("count");
				count++;
				application.setAttribute("count", count);
				
			}else{
				int count=1;
				application.setAttribute("count", count);
			}
			
			session.setAttribute("uname", uname);
			//request.setAttribute("uname", uname);
			
			response.sendRedirect("/MVCDemo/error404.jsp");
		}
		
	}

	/**
	 * The doPost method of the servlet. <br>
	 *
	 * This method is called when a form has its tag value method equals to post.
	 * 
	 * @param request the request send by the client to the server
	 * @param response the response send by the server to the client
	 * @throws ServletException if an error occurred
	 * @throws IOException if an error occurred
	 */
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doGet(request, response);
	}

}