client.java

设计模式描述设计模式描述设计模式描述设计模式描述

/*
 * Created on 2005-5-11
 * 意图 动态地给一个对象添加一些额外的职责。
 * 就增加功能来说，Decorator 模式相比生成子类更为灵活。
 * 适用性 在不影响其他对象的情况下，以动态、透明的方式
 * 给单个对象添加职责。处理那些可以撤消的职责。
 * 当不能采用生成子类的方法进行扩充时。
 * 一种情况是，可能有大量独立的扩展，为支持每一种
 * 组合将产生大量的子类，使得子类数目呈爆炸性增长。
 * 另一种情况可能是因为类定义被隐藏，或类定义不能
 * 用于生成子类。 
 */
package com.test.pattern.struct.decorator;

/**
 * @author Administrator
 * 
 * TODO To change the template for this generated type comment go to Window -
 * Preferences - Java - Code Style - Code Templates
 */
abstract class Component {
	public abstract void Draw();
}

class ConcreteComponent extends Component {
	private String strName;

	public ConcreteComponent(String s) {
		strName = s;
	}

	public void Draw() {
		System.out.println("ConcreteComponent - " + strName);
	}
}

abstract class Decorator extends Component {
	protected Component ActualComponent;

	public void SetComponent(Component c) {
		ActualComponent = c;
	}

	public void Draw() {
		if (ActualComponent != null)
			ActualComponent.Draw();
	}
}

class ConcreteDecorator extends Decorator {
	private String strDecoratorName;

	public ConcreteDecorator(String str) {
		// how decoration occurs is localized inside this decorator
		// For this demo, we simply print a decorator name
		strDecoratorName = str;
	}

	public void Draw() {
		CustomDecoration();
		super.Draw();
	}

	void CustomDecoration() {
		System.out.println("In ConcreteDecorator: decoration goes here");
		System.out.println(strDecoratorName);
	}
}

/// <summary>
/// Summary description for Client.
/// </summary>

public class Client {
	Component Setup() {
		ConcreteComponent c = new ConcreteComponent(
				"This is the real component");

		ConcreteDecorator d = new ConcreteDecorator(
				"This is a decorator for the component");

		d.SetComponent(c);

		return d;
	}

	public static void main(String[] args) {
		Client client = new Client();
		Component c = client.Setup();
		// The code below will work equally well with the real component,
		// or a decorator for the component
		c.Draw();

	}
}