login.jsp
1 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> 2 <% 3 String path = request.getContextPath(); 4 String basePath = request.getScheme() + "://" 5 + request.getServerName() + ":" + request.getServerPort() 6 + path + "/"; 7 %> 8 9 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 10 <html> 11 <head> 12 <base href="<%=basePath%>"> 13 14 <title>My JSP 'login.jsp' starting page</title> 15 16 <meta http-equiv="pragma" content="no-cache"> 17 <meta http-equiv="cache-control" content="no-cache"> 18 <meta http-equiv="expires" content="0"> 19 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 20 <meta http-equiv="description" content="This is my page"> 21 <!-- 22 <link rel="stylesheet" type="text/css" href="styles.css"> 23 --> 24 25 <script type="text/javascript" src="js/jquery-1.8.3.js"> 26 </script> 27 </head> 28 <script type="text/javascript"> 29 function chkName() { 30 var name = $("#username").val(); 31 alert(name); 32 //name为输入的值 33 var xmlhttp; 34 if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari 35 xmlhttp = new XMLHttpRequest(); 36 } else {// code for IE6, IE5 37 xmlhttp = new ActiveXObject("Microsoft.XMLHTTP"); 38 } 39 //这一段代码可以直接使用 40 xmlhttp.open("get","server.jsp?name="+name,true); 41 xmlhttp.send(); 42 43 xmlhttp.onreadystatechange=function(){ 44 45 if(xmlhttp.readyState==4&&xmlhttp.status==200){ 46 47 var str=xmlhttp.responseText;//成功响应结束，取得响应文本 48 //alert("xx"+$.trim(str)+"xx"); 49 if($.trim(str)=="true"){//需要去空格 50 $("#msg").html("用户已存在！"); 51 }else{ 52 $("#msg").html("此用户可用！"); 53 } 54 } 55 } 56 57 58 } 59 </script> 60 <body> 61 <form action="login.action" method="post"> 62 <div> 63 用户名： 64 <input name="username" type="text" value="" id="username" 65 onblur="chkName()" /> 66 <span id="msg"></span> 67 </div> 68 69 <input type="submit" value="提交" /> 70 </form> 71 </body> 72 </html>
server.jsp
1 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> 2 3 <% 4 String name=request.getParameter("name"); 5 if("sa".equals(name)){ 6 out.print("true"); 7 }else{ 8 out.print("false"); 9 } 10 11 %>