36.二级菜单联动

//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









    
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