麻烦老师帮忙看下，有没有优化的空间

来源：3-6 自由编程

曼曼喜欢你

2019-03-28 12:08:49

Servlet

package com.imooc.testsongs;

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 SongsServlet
*/
@WebServlet("/SongsServlet")
public class SongsServlet extends HttpServlet {
private static final long serialVersionUID = 1L;

public SongsServlet() {
super();
// TODO Auto-generated constructor stub
}

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String type =request.getParameter("p");
List list = new ArrayList();

if(type!=null && type.equals("pop")) {
list.add("稻香");
list.add("晴天");
list.add("告白气球");
}else if(type!=null && type.equals("classic")) {
list.add("千千阙歌");
list.add("傻女");
list.add("七友");
}else if(type!=null && type.equals("rock")) {
list.add("一块红布");
list.add("假行僧");
list.add("新长征路上");
}

String json=JSON.toJSONString(list);
System.out.println(json);
response.setContentType("text/html;charset=UTF-8");
response.getWriter().println(json);
}

}

html

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<input id="pop" type="button" value="流行歌曲">
<input id="classic" type="button" value="经典歌曲">
<input id="rock" type="button" value="摇滚歌曲">

<div id="container"></div>

<script type="text/javascript" src="js/jquery-3.3.1.js"></script>
<script type="text/javascript">
//流行歌曲
$("#pop").click(function() {
$(function() {
$.ajax({
"url" : "/ajax/SongsServlet",
"type" : "get",
"data" : "p=pop",
"dataType" : "json",
"success" : function(json) {
console.log(json);
var html = "";
for (var i = 0; i < json.length; i++) {
html = html + "<p>" + json[i] + "</p>"

}
document.getElementById("container").innerHTML = html;
},
"error" : function(xmlhttp, errorText) {
if (xmlhttp.status == "404") {
alert("页面不存在");
} else if (xmlhttp.status == "405") {
alert("无效的请求");
} else if (xmlhttp.status == "500") {
alert("服务器错误");
} else {
alert("异常");
}
}

})
})
})
//经典歌曲
$("#classic").click(function() {
$(function() {
$.ajax({
"url" : "/ajax/SongsServlet",
"type" : "get",
"data" : "p=classic",
"dataType" : "json",
"success" : function(json) {
console.log(json);
var html = "";
for (var i = 0; i < json.length; i++) {
html = html + "<p>" + json[i] + "</p>"

}
document.getElementById("container").innerHTML = html;
},
"error" : function(xmlhttp, errorText) {
if (xmlhttp.status == "404") {
alert("页面不存在");
} else if (xmlhttp.status == "405") {
alert("无效的请求");
} else if (xmlhttp.status == "500") {
alert("服务器错误");
} else {
alert("异常");
}
}

})
})
})

//摇滚歌曲
$("#rock").click(function(){
$(function() {
$.ajax({
"url" : "/ajax/SongsServlet",
"type" : "get",
"data" :"p=rock",
"dataType":"json",
"success":function(json){
console.log(json);
var html="";
for(var i=0;i<json.length;i++){
html=html+"<p>"+json[i]+"</p>"

}
document.getElementById("container").innerHTML=html;
},
"error":function(xmlhttp,errorText){
if(xmlhttp.status=="404"){
alert("页面不存在");
}else if(xmlhttp.status=="405"){
alert("无效的请求");
}else if(xmlhttp.status=="500"){
alert("服务器错误");
}else{
alert("异常");
}
}

})
})
})
</script>
</body>
</html>