Ajax登陆实例

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index.jsp文件:

代码

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<html>
<head>
<script>
//设一个变量
var XMLHttpReq=false;
//创建一个XMLHttpRequest对象
function createXMLHttpRequest(){
if(window.XMLHttpRequest){ //Mozilla
XMLHttpReq=new XMLHttpRequest();
}
else if(window.ActiveXObject){
try{
XMLHttpReq=new ActiveXObject("Msxml2.XMLHTTP");
}catch(e){
try{
XMLHttpReq=new ActiveXObject("Microsoft.XMLHTTP");
}catch(e){}
}
}
}
//发送请求函数
function send(url){
createXMLHttpRequest();
XMLHttpReq.open("GET",url,true);
XMLHttpReq.onreadystatechange=proce; //指定响应的函数
XMLHttpReq.send(null); //发送请求
}
function proce(){
if(XMLHttpReq.readyState==4){ //对象状态
if(XMLHttpReq.status==200){//信息已成功返回，开始处理信息
var res=XMLHttpReq.responseXML.getElementsByTagName("content")[0].firstChild.data;
window.alert(res);
}else{
window.alert("所请求的页面有异常");
}
}
}
//身份验证
function check(){
var name=document.getElementById("name").value;
if(name==""){
alert("请输入内容");
return false;
}
else{
send('login?name='+name);
}
}
</script>
</head>
<body>
<form action="login" method="post">
<tr><td>姓名: <input id="name" type="text" name="name"/>
<input type="button" value="检测" onClick="check()"/>
</td>
</tr>
</form>
</body>
</html>

TestA.java这是一个Servlet文件:

代码

package tt;
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 TestA extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
String name=request.getParameter("name");
response.setContentType("text/xml; charset=utf-8");
response.setHeader("Cache-Control","no-cache");
PrintWriter out=response.getWriter();
out.println("<pront>");
if(name.equals("and4walker")){
out.println("<content>"+"对不起,此名已经注册"+"</content>");
}else{
out.println("<content>"+"可以注册"+"</content>");
}
out.println("</pront>");
out.close();
}
}

web.xml文件:

代码