Ajax验证用户名是否重复的简单的问题（无数据库）

双人鱼XKQ 发布于 2012/12/19 07:10

阅读 1K+

答案 6

Apache Tomcat

使用Ajax实现验证是否有该用户名，如果有，则弹出提示框已有该用户名如果没有，则弹出可以使用该用户名。

问题：提示用户用户名不能为空的onblur事件可以实现，但是无法验证用户名？？

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代码

reg.jsp

*****

<%@ page language="java" pageEncoding="UTF-8"%>
<html>
<head>
<title>注册页面</title>
<script type="text/javascript">
function checkUser(ouser){
var uname=ouser.value;
if(!uname){
alert("用户的账号不能为空！");
ouser.focus();
return;
}
//创建get请求的字符串
var url="servlet/DoReg?uname="+uname;
//创建一个XMLHttpRequest对象
xmlHttpRequest=createXmlHttpRequest();
//设置回调函数
xmlHttpRequest.onreadystatechange=haoLeJiaoWo;
//初始 xmlHttpRequest
xmlHttpRequest.open("get",url,true);
//发送请求
xmlHttpRequest.send(null);

}
function haoLeJiaoWo(){
if(xmlHttpRequest.readystate==4 && xmlHttpRequest.status==200){
var result=xmlHttpRequest.responseText;
//空格去除
result=result.replace(/(^\s*)|(\s*$)/g,"");
if(result=="true"){
alert("用户名已经存在！");
}else{
alert("用户名可以使用！");
}
}
}

function createXmlHttpRequest(){
if(window.XMLHttpRequest){
return new XMLHttpRequest();
}else{
return new ActiveXObject("Microsoft.XMLHTTP");
}
}
</script>
</head>
<body>
<form name="myform" action="servlet/DoReg" method="get">
<table align="center">
<tr>
<td>用户账号：<input name="uname" onblur="checkUser(this)"><td>
</tr>
</table>
</form>
</body>
</html>

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DoReg.java

********

package com.pb.servlet;

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 DoReg extends HttpServlet {

@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String uname=req.getParameter("uname");
PrintWriter out=resp.getWriter();
boolean UExsixt=false;
if("accp".equals(uname)){
UExsixt=true;
out.print(UExsixt);
}else{
out.print(UExsixt);
}
}

@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
this.doGet(req, resp);
}
}

**************************************

web.xml配置

*********

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<servlet>
<servlet-name>DoReg</servlet-name>
<servlet-class>com.pb.servlet.DoReg</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>DoReg</servlet-name>
<url-pattern>/servlet/DoReg</url-pattern>
</servlet-mapping>
</web-app>

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目录结构