组合模式

将对象组合成树状层出结构，使用户能一致地使用叶子节点和分支节点

package com.jerry.design.composite;

import java.util.ArrayList;

import java.util.List;


	// 测试类
public class Test {

	public static void main(String[] args) {
		
		Component root = new Composite();
		Component c1 = new Composite();
		Component c2 = new Composite();
		
		Component l1 = new Leaf();
		Component l2 = new Leaf();
		Component l3 = new Leaf();
		
		root.addChild(c1);
		root.addChild(c2);
		root.addChild(l1);
		c1.addChild(l2);
		c1.addChild(l3);
		
		System.out.println(root.getChild(0));
		System.out.println(root.getChild(1));
		System.out.println(root.getChild(2));
		
	}
}
interface Component{
	 public void doSomething();
	 public void addChild(Component c);
	 public void removeChild(Component c);
	 public Component getChild(int index);
}

class Composite implements Component{
	
	private List<Component> children = null;

	@Override
	public void doSomething() {
		if(children!=null){
			for(Component c:children){
				c.doSomething();
			}
		}
		
	}

	@Override
	public void addChild(Component c) {
		if(children==null){
			children = new ArrayList<Component>();
		}
		children.add(c);
	}

	@Override
	public void removeChild(Component c) {
		if(children!=null){
			children.remove(c);
		}
		
	}

	@Override
	public Component getChild(int index) {
		if(children!=null){
			return children.get(index); 
		}
		return null;
	}
	
}


class Leaf extends Composite{
	
	public void doSomething() {
		System.out.println("Leaf is doSomething()");
	}
	
}