这次给大家带来AJAX如何检测用户名是否具有重复性,AJAX检测用户名是否具有重复性的注意事项有哪些,下面就是实战案例,一起来看一下。

先给大家展示下效果图,然后再给大家撸代码,效果图如下所示:

下面写一个简单的例子,检测用户名是否唯一(直接撸代码):

前端界面:

<%@ page language="java" contentType="text/html; charset=GB18030" pageEncoding="GB18030"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" ""> <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" width="104" height="23" style="cursor:hand;" onClick="checkUser(form1.username);"></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文件:

<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('GET', 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('checkUser.jsp?user='+userName.value); } } </script>

jsp文件: