利用Ajax检测用户名是否被占用的完整实例-学习AJAX-JavaScript编程-硕编程

利用Ajax检测用户名是否被占用的完整实例

适合人群：ajax和jquery入门

采用ajax实现用户名验证

使用jquery给出提示信息

用户注册的时候，使用ajax实现检测用户名是否已经被注册过，很多细节没有实现，给大家做个简单普及。

<%@ 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>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<title>用户注册页面</title>
<script src="https://libs.baidu.com/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript">
	var xmlhttp;
	function createxmlhttprequest(){
		if(window.xmlhttprequest){
			xmlhttp = new xmlhttprequest();
		}else if(window.activexobject){
			xmlhttp = new activexobject("microsoft.xmlhttp");
		}
	}
	function validate(account){
		createxmlhttprequest();
		xmlhttp.open("get","validateservlet?account="+account,true);
		xmlhttp.onreadystatechange = callback;
		xmlhttp.send(null);
	}
	function callback(){
		if(xmlhttp.readystate==4){
				if(xmlhttp.status==200){
					var text = xmlhttp.responsetext;
					if(text=="true"){
						//document.getelementbyid("msg").innerhtml = "该手机号已经被注册过";
						$("#msg").text("该手机号已经被注册");
						$("#sub").attr("disabled","true");//添加disabled属性，让按钮不可用
					}else{
						//document.getelementbyid("msg").innerhtml = "";
						$("#msg").text("");
						$("#sub").removeattr("disabled");//移除disabled属性，让按钮可用
						
					}
				}else{
					alert("请求失败，错误码="+xmlhttp.status);
				}
		}
	}
	function checkinfo(){
		var account = $("#account").val();
		var pwd1 = $("#pwd1").val();
		var pwd2 = $("#pwd2").val();
		if(account==""||account==null){
			$("#msg").text("账号不能为空");
			$("#sub").attr("disabled","true");
			return false;
		}
		if(pwd1==""||pwd1==null||pwd2==""||pwd2==null||pwd1!=pwd2){
			$("#info").text("密码不能为空或者两次密码不一致");
			$("#sub").attr("disabled","true");
			return false;
		}
		$("#msg").text("");
		$("#info").text("");
		$("#sub").removeattr("disabled");
	}
	function submit(){
		checkinfo();
		$("#reg").submit();
	}
 
</script>
</head>
<body>
<form id="reg" name="reg" action="registerservlet" method="post">
账号：<input type="text" name="account" id="account" onblur="validate(this.value);">
<span id="msg" style="color:red">请输入手机号<br>
密码：<input type="password" id="pwd1" name="password1" onblur="checkinfo();"><br>
确认密码：<input type="password" id="pwd2" name="password2" onblur="checkinfo();">
<span id="info" style="color:red"><br>
<input type="button" id="sub" value="提交" onclick="submit();">
</form>
</body>
</html>

下面是validateservlet模拟实现，没有做真正的数据库表数据检测，大家自行完成。

package com.ambow.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;
 
@webservlet("/validateservlet")
public class validateservlet extends httpservlet {
	private static final long serialversionuid = 1l;
 public validateservlet() {
  super(); 
 }
	protected void doget(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
		printwriter pw = response.getwriter();
		string account = request.getparameter("account");
		system.out.println("account"+account);
		if("123".equals(account)) {
			pw.print("true");
		}else {
			pw.print("false");
		}
	}
	protected void dopost(httpservletrequest request, httpservletresponse response) throws servletexception, ioexception {
		doget(request, response);
	}
}

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