设计模式之【外观模式-Facade】

外观模式（Facade）
外观模式是为了解决类与类之家的依赖关系的
像spring一样，可以将类和类之间的关系配置到配置文件中
而外观模式就是将他们的关系放在一个Facade类中
降低了类类之间的耦合度，该模式中没有涉及到接口

一、3个基础类模式

package Facade;

public class CPU {
    public void startup(){
        System.out.println("cpu 启动!");
    }
    public void shutdown(){
        System.out.println("cup 关闭");
    }

}

package Facade;

public class Memory {
    public void startup(){
        System.out.println("内存 启动!");
    }
    public void shutdown(){
        System.out.println("内存  关闭");
    }
}

package Facade;

public class Disk {
    public void startup(){
        System.out.println("硬盘 启动!");
    }
    public void shutdown(){
        System.out.println("硬盘 关闭");
    }
}

二、映射类关系（降低单元类之间的关系）

 1 package Facade;
 2
 3 public class Computer {
 4     private CPU cpu;
 5     private Memory memory;
 6     private Disk disk;
 7
 8     public Computer(){
 9         this.cpu = new CPU();
10         this.memory = new Memory();
11         this.disk = new Disk();
12     }
13     public void startup(){
14         System.out.println("start the computer...~");
15         cpu.startup();
16         memory.startup();
17         disk.startup();
18         System.out.println("start the computer finished!");
19     }
20     public void shutdown(){
21         System.out.println("shutdown the computer...~");
22         cpu.shutdown();
23         memory.shutdown();
24         disk.shutdown();
25         System.out.println("shutdown the computer finished!");
26     }
27
28 }

三、客户端操作

 1 package Facade;
 2
 3 public class User {
 4
 5     public static void main(String[] args) {
 6         // TODO Auto-generated method stub
 7         Computer cpu = new Computer();
 8         cpu.startup();
 9         cpu.shutdown();
10     }
11
12 }

 四、结果

 1 start the computer...~
 2 cpu 启动!
 3 内存 启动!
 4 硬盘 启动!
 5 start the computer finished!
 6 shutdown the computer...~
 7 cup 关闭
 8 内存  关闭
 9 硬盘 关闭
10 shutdown the computer finished!