search

Home >Web Front-end >JS Tutorial >How to check if username is unique using AJAX

How to check if username is unique using AJAX

一个新手
一个新手Original
2017-09-27 09:35:471748browse


After learning theory, you must use practical operations to consolidate your knowledge.

Write a simple example below to check whether the user name is unique (code directly):

Front-end interface: 

<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%><!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=GB18030"><title>检测用户名是否唯一</title><style type="text/css"><!--#toolTip {    position:absolute;    left:331px;    top:39px;    width:98px;    height:48px;    padding-top:45px;    padding-left:25px;    padding-right:25px;    z-index:1;    display:none;    color:red;    background-image: url(images/tooltip.jpg);}--></style></head><body style="margin: 0px;"><form method="post" action="" name="form1"><table width="509" height="352" border="0" align="center" cellpadding="0" cellspacing="0" background="images/bg.gif">
  <tr>
    <td height="54"> </td>
  </tr>
  <tr>
    <td height="253" valign="top">
    <p style="position:absolute;">


    <table width="100%" height="250" border="0" cellpadding="0" cellspacing="0">
      <tr>
        <td width="18%" height="54" align="right" style="color:#8e6723 "><b>用户名：</b></td>
        <td width="49%"><input name="username" type="text" id="username" size="32"></td>
        <td width="33%"><img  src="images/checkBt.jpg"    style="max-width:90%"  style="max-width:90%" style="cursor:hand;" onClick="checkUser(form1.username);" alt="How to check if username is unique using AJAX" ></td>
      </tr>
      <tr>
        <td height="51" align="right" style="color:#8e6723 "><b>密码：</b></td>
        <td><input name="pwd1" type="password" id="pwd1" size="35"></td>
        <td rowspan="2">     <p id="toolTip"></p></td>
      </tr>
      <tr>
        <td height="56" align="right" style="color:#8e6723 "><b>确认密码：</b></td>
        <td><input name="pwd2" type="password" id="pwd2" size="35"></td>
        </tr>
      <tr>
        <td height="55" align="right" style="color:#8e6723 "><b>E-mail：</b></td>
        <td colspan="2"><input name="email" type="text" id="email" size="45"></td>
      </tr>
      <tr>
        <td> </td>
        <td colspan="2"><input type="image" name="imageField" src="images/registerBt.jpg"></td>
      </tr>
    </table>
    </p>
    </td>
  </tr>
  <tr>
    <td> </td>
  </tr></table></form></body></html>

AJAX file: 

<script language="javascript">function createRequest(url) {
    http_request = false;    
    if (window.XMLHttpRequest) {                                   // 非IE浏览器
        http_request = new XMLHttpRequest();                          //创建XMLHttpRequest对象
    } else if (window.ActiveXObject) {                             // IE浏览器
        try {
            http_request = new ActiveXObject("Msxml2.XMLHTTP");    //创建XMLHttpRequest对象
        } catch (e) {            
        try {
                http_request = new ActiveXObject("Microsoft.XMLHTTP");  //创建XMLHttpRequest对象
           } catch (e) {}
        }
    }    if (!http_request) {
        alert("不能创建XMLHttpRequest对象实例！");        
        return false;
    }
    http_request.onreadystatechange = getResult;                       //调用返回结果处理函数
    http_request.open(&#39;GET&#39;, url, true);                               //创建与服务器的连接
    http_request.send(null);                                       //向服务器发送请求}function getResult() {
    if (http_request.readyState == 4) {             // 判断请求状态
        if (http_request.status == 200) {           // 请求成功，开始处理返回结果
            document.getElementById("toolTip").innerHTML=http_request.responseText; //设置提示内容
            document.getElementById("toolTip").style.display="block";   //显示提示框
        } else {                            // 请求页面有错误
            alert("您所请求的页面有错误！");
        }
    }
}function checkUser(userName){
    if(userName.value==""){
        alert("请输入用户名！");userName.focus();return;
    }else{
        createRequest(&#39;checkUser.jsp?user=&#39;+userName.value);
    }
}</script>

jsp file:

This example does not connect to the database, but simply uses an array to simply represent registered users. 

<%@ page language="java" import="java.util.*" pageEncoding="GB18030" %>
<%
    String[] userList={"明日科技","mr","mrsoft","wgh"};         //创建一个一维数组
    String user=new String(request.getParameter("user").getBytes("ISO-8859-1"),"GB18030");  //获取用户名
    Arrays.sort(userList);                                  //对数组排序 
    int result=Arrays.binarySearch(userList,user);              //搜索数组
    if(result>-1){        
    out.println("很抱歉，该用户名已经被注册！");          //输出检测结果
    }else{        
    out.println("恭喜您，该用户名没有被注册！");          //输出检测结果
    }
%>

Rendering

How to check if username is unique using AJAX

How to check if username is unique using AJAX

The above is the detailed content of How to check if username is unique using AJAX. For more information, please follow other related articles on the PHP Chinese website!

Statement：
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn
Previous article：Usage of text() in jQuery document operationsNext article：Usage of text() in jQuery document operations

Related articles

See more