场景

把部分和整体用树形结构来表示，从而使客户端可以使用统一的方式处理部分对象和整体对象。

核心

• 抽象构件角色：
  定义了叶子和容器的共同点
• 叶子构件角色：
  无字节点
• 容器构件角色：
  有容器特征，可以包含子节点

UML

百度百科.jpg

代码

package com.amberweather.composite;

public interface Component {
    void operation();
}
//叶子组件
interface Leaf extends Component{
    
}
//容器组件
interface Composite extends Component{
    void add(Component c);
    void remove(Component c);
    Component getChild(int index);
}

package com.amberweather.composite;
/**
 * 叶子图片的实现
 * @author HT
 *
 */
public class MyImage implements Leaf{
    String name;
    
    public MyImage(String name) {
        super();
        this.name = name;
    }

    @Override
    public void operation() {
        System.out.println("访问到了图片:"+name+"----->并进行了操作");
    }
}

package com.amberweather.composite;
/**
 * 叶子视屏的实现
 * @author HT
 *
 */
public class MyVideo implements Leaf{
    String name;
    
    public MyVideo(String name) {
        super();
        this.name = name;
    }

    @Override
    public void operation() {
        System.out.println("访问到了视屏:"+name+"----->并进行了操作");
    }
}

package com.amberweather.composite;

import java.util.ArrayList;
import java.util.List;
/**
 * 父节点容器的实现
 * @author HT
 *
 */
public class MyFolder implements Composite{
    String name;
    
    public MyFolder(String name) {
        super();
        this.name = name;
    }

    List<Component> list = new ArrayList();
    //注意它的operation会遍历其中的所有子节点
    @Override
    public void operation() {
        System.out.println("访问到了文件夹:"+name+"----->并进行了操作");
        for(Component c : list){
            c.operation();
        }
    }

    @Override
    public void add(Component c) {
        list.add(c);
    }

    @Override
    public void remove(Component c) {
        list.remove(c);
    }

    @Override
    public Component getChild(int index) {
        return list.get(index);
    }
}

package com.amberweather.composite;

public class Client {
    public static void main(String[] args) {
        Composite folder = new MyFolder("D:/");
        Component image = new MyImage("自拍");
        Component video = new MyVideo("mv");
        
        
        Composite childeFolder = new MyFolder("学习视屏");
        Component childeVideo1 = new MyVideo("数学");
        Component childeVideo2 = new MyVideo("语文");
        Component childeVideo3 = new MyVideo("英语");
        childeFolder.add(childeVideo1);
        childeFolder.add(childeVideo2);
        childeFolder.add(childeVideo3);
        
        folder.add(image);
        folder.add(video);
        folder.add(childeFolder);
        folder.operation();
    }
}

image.png