点击按钮怎么没反应

package com.imooc.servlet;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

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 com.alibaba.fastjson.JSON;

/**
 * Servlet implementation class songservlet
 */
@WebServlet("/song")
public class songservlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public songservlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		String type = request.getParameter("t");
        List<String> list = new ArrayList<>();
        if(type.equals("popular")) {
            list.add("稻香");
            list.add("晴天");
            list.add("告白气球");
        }else if(type.equals("classic")) {
            list.add("千千阙歌");
            list.add("傻女");
            list.add("七友");
        }else if(type.equals("rock")) {
            list.add("一块红布");
            list.add("家行政");
            list.add("新长征路上的摇滚");
        }
        String json = JSON.toJSONString(list);
        System.out.println(json);
        response.setContentType("text/html;charset=utf-8");
        response.getWriter().println(json);
     
    }
	

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript" src="js/jquery-3.4.0.js"></script>
<script type="text/javascript">
 $(function()){
	 $(".popular").click(function(){
	        $.ajax({
	            "url":"/FirstServlet/song",
	            "type":"get",
	            "data":"t=popular",
	            "dataType":"json",
	            "success":function(json) {
	                console.log(json);
	                 for(var i =0;i<json.length;i++){
	                     $("#song").append("<h1>"+json[i]+"<h1>");
	                 }
	            }
	        })
	    })
 }
    
</script>
</head>
<body>
 
    <input type="button" value="流行歌曲" id = "popular" class="popular">
    <input type="button" value="经典歌曲" id = "classic" class="classic">
    <input type="button" value="摇滚歌曲" id= "rock" class="rock">
    <div id="song"></div>
 
</body>
</html>

the_shy 2019-05-02

源自：jQuery与Ajax入门 3-6 自由编程