合成模式

合成模式属于对象的结构模式，有时又叫做“部分——整体”模式。合成模式将对象组织到树结构中，可以用来描述整体与部分的关系。合成模式可以使客户端将单纯元素与复合元素同等看待。通常用树结构来表示这种部分、整体的关系：

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

//抽象构建接口
interface Component{
    public void printNode(String str);
}

//树枝类
class Composite implements Component{

    private List<Component> childs = new ArrayList<Component>();
    private String name;
    
    public Composite(String name){
        this.name = name;
    }
    
    public void add(Component child){
        childs.add(child);
    }
    
    public void remove(int index){
        childs.remove(index);
    }
    
    public List<Component> getChild(){
        return childs;
    }
    
    @Override
    public void printNode(String str) {
        System.out.println(str + "+" + name);
        if(childs != null){
            str += " ";
            for(Component c: childs)
                c.printNode(str);
        }
    }
    
}

//树叶类
class Leaf implements Component{

    private String name;
    
    public Leaf(String name){
        this.name = name;
    }
    
    @Override
    public void printNode(String str) {
        System.out.println(str + "-" + name);
    }
    
}

public class MyTest {

    /**
     * @param args
     */
    public static void main(String[] args) {
        Composite root = new Composite("根");
        Composite c1 = new Composite("树枝1");
        Composite c2 = new Composite("树枝2");
        
        Leaf leaf1 = new Leaf("树叶1");
        Leaf leaf2 = new Leaf("树叶2");
        Leaf leaf3 = new Leaf("树叶3");
        
        root.add(c1);
        root.add(c2);
        c1.add(leaf1);
        c1.add(leaf2);
        c2.add(leaf3);
    }

}