Ajax(Asychronous JavaScript and XML)笔记

1 Ajax简介

1 ajax概念

2 什么是同步？什么是异步？

3 ajax原理

2 JavaScript原生的ajax

1 ajax.html代码

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>

<script type="text/javascript">

    function fn1(){
        //1、创建ajax引擎对象 ---- 所有的操作都是通过引擎对象
        var xmlHttp = new XMLHttpRequest();
        //2、绑定监听 ---- 监听服务器是否已经返回相应数据
        xmlHttp.onreadystatechange = function(){
            if(xmlHttp.readyState==4&&xmlHttp.status==200){
                //5、接受相应数据
                var res = xmlHttp.responseText;
                document.getElementById("span1").innerHTML = res;
            }
        }
        //3、绑定地址
        xmlHttp.open("GET","/WEB22/ajaxServlet?name=lisi",true);
        //4、发送请求
        xmlHttp.send();
        
    }
    function fn2(){
        //1、创建ajax引擎对象 ---- 所有的操作都是通过引擎对象
        var xmlHttp = new XMLHttpRequest();
        //2、绑定监听 ---- 监听服务器是否已经返回相应数据
        xmlHttp.onreadystatechange = function(){
            if(xmlHttp.readyState==4&&xmlHttp.status==200){
                //5、接受相应数据
                var res = xmlHttp.responseText;
                document.getElementById("span2").innerHTML = res;
            }
        }
        //3、绑定地址
        xmlHttp.open("POST","/WEB22/ajaxServlet",false);
        //4、发送请求
        xmlHttp.setRequestHeader("Content-type","application/x-www-form-urlencoded");
        xmlHttp.send("name=wangwu");
        
    }

    
</script>

</head>
<body>
    <input type="button" value="异步访问服务器端" onclick="fn1()"><span id="span1"></span>
    <br>
    <input type="button" value="同步访问服务器端" onclick="fn2()"><span id="span2"></span>
    <br>
    <input type="button" value="测试按钮" onclick="alert()">
</body>
</html>

2 AjaxServlet代码

package www.test.ajax01;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class AjaxServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        
        //response.getWriter().write("zhangsan");
        
        /*try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }*/
        
        String parameter = request.getParameter("name");
        
        response.getWriter().write(Math.random()+parameter);
        
    }

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