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组合模式用于让客户端不再区分操作的是组合对象还是叶子对象，而是以一个统一的方式来操作。它的关键在于使用一个抽象的组件，来代表组合对象和叶子对象。这样客户就可以不用区分到底操作的是组合对象还是叶子对象了，只需要把他们全部当作组件对象进行统一操作就可以了。

public abstract class Component {
    public String name = null;
    
    public Component(String name) {
        this.name = name;
    }
    
    public void addChild(Component component) {
        throw new UnsupportedOperationException();
    }
    
    public void removeChild(Component component) {
        throw new UnsupportedOperationException();
    }
    
    public Component getComponent(int index) {
        throw new UnsupportedOperationException();
    }
    
    public abstract String getName();
    
}
import java.awt.List;
import java.util.ArrayList;
public class Compositive extends Component{
    private ArrayList<Component> componentlist = new ArrayList<Component>();
    public Compositive(String name) {
        super(name);
    }
    
    public String getName() {
        return super.name;
    }
    
    public void addChild(Component component) {
        if(component!= null) {
            componentlist.add(component);
        }
    }
    
    public void removeChild(Component component) {
        if(componentlist!= null && componentlist.contains(component)) {
            componentlist.remove(component);
        }
    }
    
    public Component getComponent(int index) {
        if(componentlist != null) {
            return componentlist.get(index);
        }
        return null;
    }
}
public class Leaf extends Component {
    public Leaf(String name) {
        super(name);
    }
    public String getName() {
        return super.name;
    }
}
public class Client {
    public static void main(String args[]) {
        Component component1 = new Compositive("组合1");
        Component component2 = new Compositive("组合2");
        Component component3 = new Compositive("组合3");
        Component component4 = new Compositive("组合4");
        Component component5 = new Compositive("组合5");
        
        Component leaf1 = new Compositive("根节点1");
        Component leaf2 = new Compositive("根节点2");
        Component leaf3 = new Compositive("根节点3");
        Component leaf4 = new Compositive("根节点4");
        Component leaf5 = new Compositive("根节点5");
        
        component1.addChild(component2);
        component1.addChild(component3);
        component1.addChild(component4);
        component1.addChild(component5);
        component2.addChild(leaf1);
        component2.addChild(leaf2);
        component3.addChild(leaf3);
        component4.addChild(leaf4);
        component4.addChild(leaf5);  
    }
}
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