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组合模式（Composite Pattern）：

一种将对象组合成树状的层次结构的模式，用来表示“部分-整体”的关系，使用户对单个对象和组合对象具有一致的访问性；又称为部分-整体模式。

组合模式，使得客户端代码可以一致地处理单个对象和组合对象，而无须关心处理的是单个对象，还是组合对象；更容易在组合体内加入新的对象，客户端不会因为加入了新的对象而更改源代码，满足OCP原则；

组合模式的角色：

抽象构件（Component）、树叶构件（Leaf）和树枝构件（Composite）；

组合模式的案例：

一般情况下，一个学校的院系包含多个学院，一个学院又包含多个系，如下，使用组合模式实现；

案例类图：

案例代码：

/**
 * 抽象组件
 */
public abstract class OrganizeComponent {

	// 名称
	private String name;
	// 描述
	private String desc;

	/**
	 * 增加
	 */
	protected void add(OrganizeComponent organizeComponent) {
		throw new UnsupportedOperationException();
	}

	/**
	 * 移除
	 */
	protected void remove(OrganizeComponent organizeComponent) {
		throw new UnsupportedOperationException();
	}

	/**
	 * 打印
	 */
	protected abstract void print();

	public String getName() {
		return name;
	}

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

	public String getDesc() {
		return desc;
	}

	public void setDesc(String desc) {
		this.desc = desc;
	}

}

欢迎大家来到IT世界,在知识的湖畔探索吧!

欢迎大家来到IT世界,在知识的湖畔探索吧!import java.util.ArrayList;
import java.util.List;

/**
 * 树枝构件
 */
public class UniversityComposite extends OrganizeComponent {

	private List<OrganizeComponent> organizeList = new ArrayList<OrganizeComponent>();

	public UniversityComposite(String name, String desc) {
		super.setName(name);
		super.setDesc(desc);
	}

	public UniversityComposite(List<OrganizeComponent> organizeList) {
		this.organizeList = organizeList;
	}

	@Override
	protected void add(OrganizeComponent organizeComponent) {
		organizeList.add(organizeComponent);
	}

	@Override
	protected void remove(OrganizeComponent organizeComponent) {
		organizeList.remove(organizeComponent);
	}

	@Override
	protected void print() {
		System.out.println("学校名称：" + this.getName());
		for (OrganizeComponent organize : this.organizeList) {
			organize.print();
		}
	}

}

/**
 * 树叶构件
 */
public class DepartmentLeaf extends OrganizeComponent {

	public DepartmentLeaf(String name,String desc) {
		super.setName(name);
		super.setDesc(desc);
	}
	
	@Override
	protected void print() {
		System.out.println("系名称：" + this.getName() + "" );
	}

}

欢迎大家来到IT世界,在知识的湖畔探索吧!public class CollegeComposite extends OrganizeComponent {

	private List<OrganizeComponent> organizeList = new ArrayList<OrganizeComponent>();

	public CollegeComposite(String name, String desc) {
		super.setName(name);
		super.setDesc(desc);
	}

	public CollegeComposite(List<OrganizeComponent> organizeList) {
		this.organizeList = organizeList;
	}

	@Override
	protected void add(OrganizeComponent organizeComponent) {
		organizeList.add(organizeComponent);
	}

	@Override
	protected void remove(OrganizeComponent organizeComponent) {
		organizeList.remove(organizeComponent);
	}

	@Override
	protected void print() {
		System.out.println("学院名称：" + this.getName() + "");
		for (OrganizeComponent organize : this.organizeList) {
			organize.print();
		}
	}

}

public class CompositeClient {

	public static void main(String[] args) {
		// 大学
		OrganizeComponent university = new UniversityComposite("清华大学","中国顶级大学");
		// 学院
		OrganizeComponent computerCollege = new CollegeComposite("计算机学院","计算机学院");
		university.add(computerCollege);
		OrganizeComponent infoEngineerCollege = new CollegeComposite("信息工程学院","信息工程学院");
		university.add(infoEngineerCollege);
		// 系
		OrganizeComponent computerApply = new DepartmentLeaf("计算机应用","计算机应用");
		computerCollege.add(computerApply);
		OrganizeComponent computerNetwork = new DepartmentLeaf("计算机网络","计算机网络");
		computerCollege.add(computerNetwork);
		OrganizeComponent computerTel = new DepartmentLeaf("计算机科学与技术","计算机科学与技术");
		computerCollege.add(computerTel);
		
		OrganizeComponent communication = new DepartmentLeaf("通信工程","通信工程");
		infoEngineerCollege.add(communication);
		OrganizeComponent information = new DepartmentLeaf("信息工程","信息工程");
		infoEngineerCollege.add(information);
		
		// 打印信息
		// university.print();
		// computerCollege.print();
		infoEngineerCollege.print();
	}

}