这是index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<br> var obj;<br> function check(){<br> //获得id为username的节点的对象<br> var usernameNode = document.getElementById("username");<br> //获得该节点的值<br> var username = usernameNode.value;</p> <pre><code>//判断浏览器的类型 if(window.XMLHttpRequest()){ //FIREFOX等 obj = new XMLHttpRequest(); }else{ //IE obj = new ActiveXObject("Microsoft.XMLHTTP"); } //注册回调函数 obj.onreadystatechange = callback; var url = "ajax?username="+username; //创建和服务器的连接 //参数1表示请求的类型'GET''POST' //参数2表示请求的服务器的地址 //参数3表示是否是异步请求 //参数4表示用户名 //参数5表示密码 //没有可以省略 obj.open("GET",url,true); //发送请求 obj.send(null); </code></pre> <p>}<br> function callback(){<br> if(obj.readyState == 4){<br> if(obj.status == 200){<br> document.getElementById("result").innerHTML=obj.responseText;<br> }<br> }<br> }<br>
username:
下面是servlet
package demo;
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;
/**
-
Servlet implementation class AjaxServlet
*/
public class AjaxServlet extends HttpServlet {
private static final long serialVersionUID = 1L;/**
- Default constructor. */ public AjaxServlet() { // TODO Auto-generated constructor stub }
/**
- @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String username = request.getParameter("username"); PrintWriter out = response.getWriter(); if("rolex".equals(username)){ out.println("not use"); }else{ out.print("can use"); } }
}
下面是web.xml
<?xml version="1.0" encoding="UTF-8"?>
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
index.jsp
AjaxServlet
AjaxServlet
demo.AjaxServlet
AjaxServlet
/ajax
