(文章翻译自Java Design Pattern: Composite)

组合模式相对来说是比较简单的，但是它在很多设计中被用到，比如SWT、Eclipse工作空间等等。它创建了一个可以通过唯一的方法访问的继承树。

类图

下面的代码实现了下面树的结构

Java 代码

import java.util.List;

import java.util.ArrayList;

//Component

interface Component {

    public void show();

}

//Composite

class Composite implements Component {

    private List<Component> childComponents = new ArrayList<Component>();

    public void add(Component component) {

    	childComponents.add(component);

    }

    public void remove(Component component) {

    	childComponents.remove(component);

    }

	@Override

	public void show() {

		for (Component component : childComponents) {

        	component.show();

        }

	}

}

//leaf

class Leaf implements Component {

	String name;

	public Leaf(String s){

		name = s;

	}

    public void show() {

        System.out.println(name);

    }

}

public class CompositeTest {

    public static void main(String[] args) {

        Leaf leaf1 = new Leaf("1");

        Leaf leaf2 = new Leaf("2");

        Leaf leaf3 = new Leaf("3");

        Leaf leaf4 = new Leaf("4");

        Leaf leaf5 = new Leaf("5");

        Composite composite1 = new Composite();

        composite1.add(leaf1);

        composite1.add(leaf2);

        Composite composite2 = new Composite();

        composite2.add(leaf3);

        composite2.add(leaf4);

        composite2.add(leaf5);

        composite1.add(composite2);

        composite1.show();

    }

}