ajax一般是和java交互,简单的ajax和java交互

前台代码为:

pageEncoding="UTF-8"%>

ajax学习

window.οnlοad=function(){

document.getElementById("btn1").οnclick=function(){

//发出已补请求

//1/得到xhr对象

var xhr=getXHR();

//2.注册状态变化监听器

xhr.onreadystatechange=function(){

if(xhr.readyState==4)

{

if(xhr.status==200)

{

alert("服务器响应了");

document.getElementById("mytext").innerHTML=xhr.responseText;

}

}

}

//3.建立与服务器的连接

xhr.open("GET","AjaxServlet"+"?time="+new Date().getTime());

//4.向服务器发出请求

xhr.send();

}

}

点我呀

后台servlet代码为：

package com.levi.servletajax;

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;

/**

* @see HttpServlet#HttpServlet()

*/

public AjaxServlet() {

super();

// TODO Auto-generated constructor stub

}

/**

* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

*/

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

this.doPost(request, response);

}

/**

* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

*/

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

response.setCharacterEncoding("utf-8");

System.out.println("ajax后台交互成功");

PrintWriter write=response.getWriter();

write.println("我是输出的文字
");

write.println("姓名:花2不谢
年龄:20");

write.flush();

}

}

其中我把那个获取XMLHttpRequest对象的方法我封装到了一个js文件。

util.js封装文件代码如下:

/**

* 得到XMLHttpRequest对象

*/

function getXHR(){

var xmlHttp;

try {

xmlHttp=new XMLHttpRequest();

}catch(e)

{

try{

xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");

}

catch(e)

{

try{

xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");

}

catch(e)

{

alert("你的浏览器不支持ajax");

return false;

}

}

}

return xmlHttp;

}

原文：https://blog.youkuaiyun.com/qq_25821067/article/details/51612167