设计模式学习(十三)(组合模式)

模式名称

组合模式(Composite Pattern)

解决问题

它在我们树型结构的问题中，模糊了简单元素和复杂元素的概念，客户程序可以向处理简单元素一样来处理复杂元素，从而使得客户程序与复杂元素的内部结构解耦。

在公司中就是一种树形结构，分为领导与普通员工，领导可能管理着部分员工和其他相对低级的领导，这时候我们可以利用组合模式来解决这个问题。

解决方法

1.Component：组合中的对象声明接口，在适当情况下实现所有类共有的默认行为，声明一个接口用于访问和管理Component的子组件。在递归结构中定义一个接口，用于访问一个父部件，并在合适的情况下实现它。（可选）

2.Leaf:在组合中表示叶节点，叶节点没有子节点，定义对象的基本行为。

3.Composite：定义有子部件的那些部件的行为，存储子部件并在Component接口实现与子部件有关的操作。

4.Client:通过Component接口操作组合部件的对象。

组合模式的优点

1.允许客户端对叶节点和枝节点一视同仁。

2.方便处理层次结构的问题。

组合模式的缺点

1.枝节点的责任比较复杂。

2.需要客户端需要加入一些判断来保证安全性。

代码

package composite;

public interface Worker {
	
	public void doSomething();

}

package composite;

public interface Worker {

public void doSomething();

}

package composite;

public class Employe implements Worker {

	private String name;
	
	public Employe(String name) {
		super();
		this.name = name;
	}
	@Override
	public void doSomething() {
		System.out.println(toString());
	}


	@Override
	public String toString() {
		// TODO Auto-generated method stub
		return "我叫"+getName()+",就一普通员工!";
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}	

}

package composite;

public class Employe implements Worker {

private String name;

public Employe(String name) {

super();

this.name = name;

}

@Override

public void doSomething() {

System.out.println(toString());

}

@Override

public String toString() {

// TODO Auto-generated method stub

return "我叫"+getName()+",就一普通员工!";

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

package composite;

import java.util.Iterator;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;


public class Leader implements Worker {
	private List<Worker> workers = new CopyOnWriteArrayList<Worker>();  
	private String name;
	
	public Leader(String name) {
		super();
		this.name = name;
	}
	public void add(Worker worker){
		workers.add(worker);
	}
	
	public void remove(Worker worker){
		workers.remove(worker);
	}
	
	public Worker getChild(int i){
		return workers.get(i);
	}
	@Override
	public void doSomething() {
		System.out.println(toString());
		Iterator<Worker> it = workers.iterator();
		while(it.hasNext()){
			it.next().doSomething();
		}
			
	}

	
	@Override
	public String toString() {
		// TODO Auto-generated method stub
		return "我叫"+getName()+", 我是一个领导,有 "+workers.size()+"下属。";
	}
	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

}

package composite;

import java.util.Iterator;

import java.util.List;

import java.util.concurrent.CopyOnWriteArrayList;

public class Leader implements Worker {

private List<Worker> workers = new CopyOnWriteArrayList<Worker>();

private String name;

public Leader(String name) {

super();

this.name = name;

}

public void add(Worker worker){

workers.add(worker);

}

public void remove(Worker worker){

workers.remove(worker);

}

public Worker getChild(int i){

return workers.get(i);

}

@Override

public void doSomething() {

System.out.println(toString());

Iterator<Worker> it = workers.iterator();

while(it.hasNext()){

it.next().doSomething();

}

@Override

public String toString() {

// TODO Auto-generated method stub

return "我叫"+getName()+", 我是一个领导,有 "+workers.size()+"下属。";

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

package composite;

public class Client {


	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Leader leader1 = new Leader("张三");
		Leader leader2 = new Leader("李四");
		Employe employe1 = new Employe("王五");
		Employe employe2 = new Employe("赵六");
		Employe employe3 = new Employe("陈七");
		Employe employe4 = new Employe("徐八");
		leader1.add(leader2);
		leader1.add(employe1);
		leader1.add(employe2);
		leader2.add(employe3);
		leader2.add(employe4);
		leader1.doSomething();
		
	}

package composite;

public class Client {

public static void main(String[] args) {

// TODO Auto-generated method stub

Leader leader1 = new Leader("张三");

Leader leader2 = new Leader("李四");

Employe employe1 = new Employe("王五");

Employe employe2 = new Employe("赵六");

Employe employe3 = new Employe("陈七");

Employe employe4 = new Employe("徐八");

leader1.add(leader2);

leader1.add(employe1);

leader1.add(employe2);

leader2.add(employe3);

leader2.add(employe4);

leader1.doSomething();

}

(完)

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