代码:
login.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>无刷新用户登录</title> <Meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <Meta http-equiv="pragma" content="no-cache"> <Meta http-equiv="cache-control" content="no-cache"> <Meta http-equiv="expires" content="0"> <script> function getXMLHTTPRequest() { var xRequest = null; if (window.XMLHttpRequest) { xRequest = new XMLHttpRequest(); } else if (window.ActiveXObject) { xRequest = new ActiveXObject("Microsoft.XMLHTTP"); } return xRequest; } function sendRequest(req,url,params,HttpMethod) { if (!HttpMethod) { HttpMethod = "POST"; } if (req) { req.open(HttpMethod,true); req.setRequestHeader("Content-Type","application/x-www-form-urlencoded"); req.onreadystatechange = processRequest; req.send(params); } } //创建浏览器兼容的XMLHttpRequest对象 var xmlhttp = getXMLHTTPRequest(); function dologin() { var name = document.getElementById("uname").value; var pwd = document.getElementById("upwd").value; if (name == "") { return false; } else if (pwd == "") { return false; } else { sendRequest(xmlhttp,"LoginServlet","username=" + name + "&userpwd=" + pwd,"POST"); } } function processRequest() { if (xmlhttp.readyState == 4 && xmlhttp.status == 200) { var prompt = document.getElementById("login"); var str = xmlhttp.responseText; if (str != 0) { prompt.innerHTML = "欢迎 <b>" + str + "</b> 登录。" + "<a href='login.jsp'>重新登录</a>"; } else { document.getElementById("error").innerHTML = "用户名或密码错误"; } } } </script> </head> <body> <div id="login"> <label>登录名</label> <input type="text" id="uname" value="" /><br /> <label>密码</label> <input type="password" id="upwd" value="" /> <label id="error"></label><br> <input type="button" value="登录" onclick="dologin()" /> </div> </body> </html>
LoginServlet.java
package com.servlet; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.servletexception; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class LoginServlet extends HttpServlet { private static final long serialVersionUID = 1L; public LoginServlet() { super(); } public void doGet(HttpServletRequest request,HttpServletResponse response) throws servletexception,IOException { doPost(request,response); } public void doPost(HttpServletRequest request,IOException { String name = request.getParameter("username"); String pwd = request.getParameter("userpwd"); PrintWriter out = response.getWriter(); if (name.equals("AJAX") && pwd.equals("AJAX")) out.print(name); else out.print(0); out.flush(); out.close(); } public void init() throws servletexception { } }
截图:
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