Ajax4部曲

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
	String path = request.getContextPath();
	String basePath = request.getScheme() + "://"
			+ request.getServerName() + ":" + request.getServerPort()
			+ path + "/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">

<title>My JSP 'ajax_test.jsp' starting page</title>
<script type="text/javascript">
	function doAjax() {
		//1 创建对象
		var xhr = new XMLHttpRequest();

		//4.接收数据
		xhr.onreadystatechange = function() {
			
			if (xhr.readyState == 4) {
				document.getElementById("mydiv").innerHTML = xhr.responseText;
			} else {
				document.getElementById("mydiv").innerHTML = "<img src='739.gif'>";
				
			} 
		}
		
		//2.创建请求
		xhr.open("get", "hi", true);

		//3.发送请求
		xhr.send(null);
		

		
	}
</script>


</head>

<body>
	<button onclick="doAjax()">偷偷点我</button>
	<div id="mydiv"></div>
</body>
</html>

 servlet代码

package cn.ljs.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class Hiservlet extends HttpServlet {

	
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.doPost(request, response);
		
		
	}

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		request.setCharacterEncoding("utf-8");
		response.setContentType("text/html;charset=utf-8");
		
		
		try {
			Thread.sleep(5000);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		
		PrintWriter out = response.getWriter();
		out.write("aaa");
		System.out.println("成功了");
	}

}

  

 

原文地址:https://www.cnblogs.com/heviny/p/10877824.html