1.客户端网页代码
<!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>
<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('http://10.65.9.181:8090/ajax/checkUser.jsp?user='+userName.value);
createRequest('http://10.65.9.181:8090/ajax/checkUser.action?user='
+ userName.value);
}
}
</script>
<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">
<div 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">
<div id="toolTip"></div>
</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>
</div>
</td>
</tr>
<tr>
<td> </td>
</tr>
</table>
</form>
</body>
</html>
值得注意的是此处核心代码：
//createRequest('http://10.65.9.181:8090/ajax/checkUser.jsp?user='+userName.value);//与jsp页面交互，可能不通过数据库
createRequest('http://10.65.9.181:8090/ajax/checkUser.action?user='+ userName.value);//与struts交互，通过后台处理。
注意此处的写法。
2.服务器端代码
Action类的代码
package com.action;
import java.util.Map;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;
import com.xzy.UserDAO;
public class CheckUserAction extends ActionSupport{
private String user;
public String findUserByName(){
String info = null;
UserDAO userdao = new UserDAO();
if(userdao.findUserByName(user)){
//info="用户名已经被注册";
Map map = (Map)ActionContext.getContext().get("request");
map.put("info", "用户名已经被注册");
return "success";
}else{
//info="用户名可以注册";
Map map = (Map)ActionContext.getContext().get("request");
map.put("info", "用户名可以注册使用");
return "fail";
}
}
public String getUser() {
return user;
}
public void setUser(String user) {
this.user = user;
}
}
struts.xml配置
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd"> <struts> <package name="myPackage" extends="struts-default"> <!-- 定义action --> <action name="checkUser" class = "com.action.CheckUserAction" method="findUserByName"> <!-- 定义处理成功后的映射页面 --> <result >/info.jsp</result> </action> </package> </struts>
info.jsp为显示信息页面
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%=request.getAttribute("info")%>
info.jsp是jsp页面，对于与安卓客户端交互的jsp页面而言，尽量略去不必要的html代码，只需要保留控制编码格式的代码和<%%>之间的处理代码,这样就避免了在安卓客户端显示不必要的垃圾代码，且提高了执行效率，降低了服务器负载。
数据库截图:
最终效果图：
