用處：樹(shù)結(jié)構(gòu)，...

先上類(lèi)圖

組合模式.jpg

案例代碼

先定義Node接口

package com.wwj.compositemode;

public interface Node {
    abstract public void p();
}

定義葉子節(jié)點(diǎn)

package com.wwj.compositemode;

/***
 * 葉子節(jié)點(diǎn)，無(wú)下一層，包含具體的內(nèi)容
 */
public class LeafNode implements Node {
    private String content;

    public LeafNode(String content){
        this.content=content;
    }

    @Override
    public void p() {
        System.out.println(content);
    }
}

定義分支節(jié)點(diǎn)

package com.wwj.compositemode;

import java.util.ArrayList;
import java.util.List;

/**
 * 分支節(jié)點(diǎn)，包含多個(gè)Node(可能是葉子節(jié)點(diǎn)也可能是分支節(jié)點(diǎn))
 */
public class BranchNode implements Node {
    private String name;
    private List<Node> nodes = new ArrayList<>();

    public BranchNode(String name){
        this.name = name;
    }
    @Override
    public void p() {
        System.out.println(name);
    }

    public void addNodes(Node node){
        this.nodes.add(node);
    }

    public List<Node> getNodes(){
        return this.nodes;
    }

    public static void tree(Node node,int depth){
        for (int i = 0; i <depth ; i++) {
            System.out.print("--");
        }
        node.p();
        if (node instanceof BranchNode){
            BranchNode branchNode = (BranchNode)node;
            for(Node n:branchNode.getNodes()){
                tree(n,depth+1);
            }
        }
    }
}

具體應(yīng)用

package com.wwj.compositemode;

public class main {
    public static void main(String[] args) {
        //最頂級(jí)菜單
        BranchNode root = new BranchNode("root");

        //第二級(jí)菜單
        BranchNode menuOne = new BranchNode("menuOne");
        BranchNode menuTwo = new BranchNode("menuTwo");
        BranchNode menuThree = new BranchNode("menuThree");

        //第三集菜單(最后一級(jí)菜單)
        LeafNode ln1 = new LeafNode("ln1");
        LeafNode ln2 = new LeafNode("ln2");
        LeafNode ln3 = new LeafNode("ln3");
        LeafNode ln4 = new LeafNode("ln4");

        //添加一級(jí)菜單
        root.addNodes(menuOne);
        root.addNodes(menuTwo);
        root.addNodes(menuThree);

        //添加二級(jí)菜單
        menuOne.addNodes(ln1);
        menuOne.addNodes(ln2);
        menuTwo.addNodes(ln3);
        menuTwo.addNodes(ln4);

        //打印所有節(jié)點(diǎn)
        BranchNode.tree(root,0);
    }
}