Java设计模式中组合模式应用详解

public abstract class Node {
    private String name;
    public Node(String name){
        this.name = name;
    }
    /**
     * 获取子节点
     * @return
     */
    public abstract List<Node> getChildren();
    public String getName() {
        return name;
    }
}
/**
 * 叶子节点
 */
public class LeafNode extends Node{
    public LeafNode(String name) {
        super(name);
    }
    @Override
    public List<Node> getChildren() {
        return null;
    }
}
/**
 * 区节点
 */
public class DistrictNode extends Node{
    private List<Node> children = new ArrayList<>();
    public DistrictNode(String name) {
        super(name);
    }
    @Override
    public List<Node> getChildren() {
        return children;
    }
    public void addChild(Node node){
        children.add(node);
    }
    public void delChild(int i){
        children.remove(i);
    }
}
 public static void main(String[] args) {
        //根目录
        DistrictNode root = new DistrictNode("root");
        //一线目录
        root.addChild(new DistrictNode("shang hai"));
        root.addChild(new DistrictNode("tian jin"));
        DistrictNode districtNode = new DistrictNode("bei jing");
        root.addChild(districtNode);
        //二级目录
        districtNode.addChild(new DistrictNode("hai dian qu"));
        districtNode.addChild(new DistrictNode("xi cheng qu"));
        DistrictNode districtNode2 = new DistrictNode("chao yang qu");
        districtNode.addChild(districtNode2);
        //三级目录
        districtNode2.addChild(new LeafNode("san li tun "));
        districtNode2.addChild(new LeafNode("guo mao"));
        System.out.println(JsonOutput.toJson(root));
    }