点击按钮以后没有反应

来源：2-3 发送请求及处理响应

China_Wang

2019-05-08 12:06:22

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
    <input id="btnLoad" type="button" value="加载">
    <div id="divContent"></div>
    <!--<script type="text/javascript" src="js/jquery-3.4.1.js"></script>-->
    <script>
        document.getElementById("btnLoad").onclick = function () {
            //1.创建XmlHttpRequest对象
            var xmlhttp;
            if(window.XMLHttpRequest){
                xmlhttp = new XMLHttpRequest();
            }
            else {
                xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
            }
            console.log(xmlhttp);
            //2.发送Ajax请求
            xmlhttp.open("GET","http://localhost:8080/ajax/content",true);
            xmlhttp.send();
            //3.处理服务器响应
            xmlhttp.readystatechange  = function () {
                console.log("xmlhttp.readyState:"+xmlhttp.readyState);
                console.log("xmlhttp.status:"+xmlhttp.status);
                //判断服务器处理状态
                if(xmlhttp.readyState === 4 && xmlhttp.status === 200){
                    var text = xmlhttp.responseText;
                    console.log(text);
                }
            }
        }
    </script>
</body>
</html>

package com.imooc.ajax;

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

@WebServlet(name = "ContentServlet",urlPatterns = "/content")
public class ContentServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.getWriter().println("<b>I'm Server Content</b>");
    }
}

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