<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP 'regUser.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">
<script type="text/javascript">
var xhr;
//创建Xhr对象的函数;
function createXhr(){
try{
//普通方式;
return new XMLHttpRequest();
}catch(e){
//异常，则另外一种方式;
return new ActiveXObject("Microsoft.XMLHTTP");
}
}
//用户名，文本框失去焦点处理函数;
function checkUser(){
xhr=createXhr();
//得到文本框中输入的内容；
var username=document.getElementById("username").value;
//设置回调函数;
xhr.onreadystatechange=callback;
//alert(username);
//设置请求方式和url，因为是get方式，请求数据直接在url的后面;
xhr.open("get","checkUserAction?username="+username);
//发送请求;
xhr.send(null);
}
function callback(){
//判断请求完成，并且成功返回;
if(xhr.readyState==4&&xhr.status==200){
var msg=document.getElementById("msg");
var res=xhr.responseText;
//alert(res);
//根据响应返回的数据，进行页面更新;
if(res=="true"){
msg.innerHTML='用户名已经存在';
}else{
msg.innerHTML='用户名可以注册';
}
}
}
</script>
</head>
<body>
<form action="regAction" method="post">
账户：<input type='text' id='username' name='username' onblur='checkUser()'/><span id='msg'></span><br/>
密码:<input type='password' name='userpwd'><br/>
邮箱：<input type='text' name='email'><br/>
地址:<input type='text' name='address'><br/>
<input type='submit' value='注册'/>
</form>
</body>
</html>
响应的Servlet代码:
package web;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CheckUserServlet extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
resp.setContentType("text/html;charset=utf-8");
PrintWriter out=resp.getWriter();
//获取提交数据;
String username=req.getParameter("username");
if("admin".equals(username)){
out.print("true");
}else{
out.print("false");
}
out.close();
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
this.doGet(req, resp);
}
}
