外观模式（Facade）

外观模式的主要作用是降低系统之间的耦合性，包含3种角色：目标类、外观类、客户端类。

 

外观模式只可以将一些复杂的类包装成一个简单的封闭接口，外观模式对客户屏蔽了复杂的子系统组件，并为一般用户提供了一个比较简单的程序设计接口。

package facade;
/**
 * @author lenovo
 * @version 1.0
 * @created 17-三月-2011 21:58:07
 */
public class Memory {

	public Memory(){

	}

	public void finalize() throws Throwable {

	}

	public void shutdown(){
		System.out.println("内存关闭");
	}

	public void startup(){
		System.out.println("内存启动");
	}

}

 

package facade;
/**
 * @author lenovo
 * @version 1.0
 * @created 17-三月-2011 21:58:20
 */
public class Disk {

	public Disk(){

	}

	public void finalize() throws Throwable {

	}

	public void shutdown(){
		System.out.println("硬盘关闭");
	}

	public void startup(){
		System.out.println("硬盘启动");
	}

}

package facade;
/**
 * @author lenovo
 * @version 1.0
 * @created 17-三月-2011 21:56:37
 */
public class Cpu {

	public Cpu(){

	}

	public void finalize() throws Throwable {

	}

	public void shutdown(){
		System.out.println("Cpu关闭");
	}

	public void startup(){
		System.out.println("Cpu启动");
	}

}
 

 

package facade;
/**
 * @author lenovo
 * @version 1.0
 * @created 17-三月-2011 21:58:37
 */
public class Computer {
	private Cpu cpu;
	private Disk disk;
	private Memory memory;

	public Computer(){
		cpu = new Cpu();
		disk = new Disk();
		memory = new Memory();
	}

	public void finalize() throws Throwable {

	}

	public void shutdown(){
		System.out.println("计算机关闭");
		cpu.shutdown();
		memory.shutdown();
		disk.shutdown();
	}
	public void startup(){
		System.out.println("计算机启动开始");
		cpu.startup();
		memory.startup();
		disk.startup();
	}

}

 

package facade;
/**
 * @author lenovo
 * @version 1.0
 * @created 17-三月-2011 21:58:45
 */
public class User {

	public User(){

	}

	public void finalize() throws Throwable {

	}
	
	public static void main(String args[]){
		Computer computer = new Computer();
		computer.startup();
		computer.shutdown();
	}

}

 

例子中的Cpu类、Disk类、Memory类为目标类，Computer类为外观类，User类为客户类。