Java Web分层架构示例-优快云博客

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;
	}
	
}



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

    public ChannelServlet() {
        super();
    }

	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);
	}

}


<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<script type="text/javascript" src="js/jquery-3.3.1.js"></script>
<script type="text/javascript">
	$(function(){
		$.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>