一个简单的ajax调用，页面上一个输入框，输入email地址后，调用ajax请求服务端对email做简单校验，服务器端用一个servlet响应和校验，然后将校验结果显示给用户
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!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=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<div style="absolute; left:200px; top:200px">
<table>
<tr>
<td>
<input type="text" id="mailIpt"/>
</td>
<td>
<input type="button" onclick="javascript:checkMail()"/>
</td>
</tr>
</table>
</div>
</body>
<script type="text/javascript">
function createXhr(){
if(window.ActiveXObject){
return new ActiveXObject("Microsoft.XMLHTTP");
}else if(window.XMLHttpRequest){
return new XMLHttpRequest();
}
}
var xhr=null;
function checkMail(){
xhr=createXhr();
var url="vm?mailIpt="+escape(document.getElementById("mailIpt").value);
xhr.open("GET",url); //XMLHttpRequest.open("GET",url,true) true是默认的，表示异步回调
xhr.onreadystatechange=displayStatus;
xhr.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
xhr.send(null); //get方式请求体设置为null，post需发送请求体
}
function displayStatus(){
if(xhr.readyState==4){ //readyState服务端状态，0无状态，1建立连接，2准备发送数据，3正在发送数据，4请求响应完毕
if(xhr.status==200){//status客户端状态，200数据已存于缓存，400url出错，500内部错误
//var status=document.getElementById("mailFormatStatus");
var mailStatus=xhr.responseText;
if(mailStatus=="true")
alert("ok");
else
alert("check mail Failed");
}
}
}
</script>
</html>
servlet代码如下：
package com;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class ValidEmailFormatServlet extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException{
response.setContentType("text/plain;charset=gbk");
String mail=(String)request.getParameter("mailIpt");
String status="false";
Pattern p=Pattern.compile("\\S+@\\S+");
Matcher m=p.matcher(mail);
if(m.matches())
status="true";
PrintWriter pw=response.getWriter();
pw.print(status);
pw.close();
}
}
web.xml中的servlet定义：
<servlet> <servlet-name>ValidEmailFormatServlet</servlet-name> <servlet-class>com.ValidEmailFormatServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ValidEmailFormatServlet</servlet-name> <url-pattern>/vm</url-pattern> </servlet-mapping>原文链接：https://www.f2er.com/ajax/163776.html
