//Channel.java
package com.imooc.ajax;
public class Channel {
private String code;
private String name;
public Channel(){
}
public Channel(String code, String name) {
super();
this.code = code;
this.name = name;
}
public String getCode() {
return code;
}
public void setCode(String code) {
this.code = code;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
//ChannelServlet.java
package com.imooc.ajax;
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 ChannelServlet
*/
@WebServlet("/channel")
public class ChannelServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public ChannelServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String level = request.getParameter("level");
String parent = request.getParameter("parent");
List chlist = new ArrayList();
if(level.equals("1")) {
chlist.add(new Channel("ai","前沿/区块链/人工智能"));
chlist.add(new Channel("web","前端/小程序/Js"));
}else if(level.equals("2")) {
if(parent.equals("ai")) {
chlist.add(new Channel("micro","微服务"));
chlist.add(new Channel("blockchain","区块链"));
chlist.add(new Channel("other","..."));
}else if(parent.equals("web")) {
chlist.add(new Channel("html","HTML"));
chlist.add(new Channel("css","CSS"));
chlist.add(new Channel("other","..."));
}
}
String json = JSON.toJSONString(chlist);
response.setContentType("text/html;charset=utf-8");
response.getWriter().println(json);
}
}
//cascade_menu.html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript" src="js/jquery-3.4.1.js"></script>
<script type="text/javascript">
$(function(){ //页面就绪函数
$.ajax({
"url":"/Ajax/channel",
"data":{"level":"1"},
"type":"get",
"dataType":"json",
"success":function(json){
console.log(json);
for(var i=0;i<json.length;i++){
var ch = json[i];
$("#lv1").append("<option value='"+ch.code+"'> " + ch.name + "</option>");
}
}
})
})
$(function(){
$("#lv1").on("change",function(){
var parent = $(this).val();
console.log(parent);
$.ajax({
"url" : "/Ajax/channel",
"data" : {"level":"2","parent":parent},
"dataType" : "json",
"type" : "get" ,
"success" : function(json){
console.log(json);
//移除所有lv2下的原始option选项
$("#lv2>option").remove();
for(var i=0;i<json.length;i++){
var ch = json[i];
$("#lv2").append("<option value='"+ch.code+"'> " + ch.name + "</option>");
}
}
})
})
})
</script>
</head>
<body>
<select id="lv1" style="width:200px;height:30px">
<option selected="selected">请选择</option>
</select>
<select id="lv2" style="width:200px;height:30px">
</select>
</body>
</html>
