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）

package Facade;

public class Computer {
    private CPU cpu;
    private Memory memory;
    private Disk disk;
    
    public Computer(){
        this.cpu = new CPU();
        this.memory = new Memory();
        this.disk = new Disk();
    }
    public void startup(){
        System.out.println("start the computer...~");
        cpu.startup();
        memory.startup();
        disk.startup();
        System.out.println("start the computer finished!");
    }
    public void shutdown(){
        System.out.println("shutdown the computer...~");
        cpu.shutdown();
        memory.shutdown();
        disk.shutdown();
        System.out.println("shutdown the computer finished!");
    }

}

三、客户端操作

package Facade;

public class User {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Computer cpu = new Computer();
        cpu.startup();
        cpu.shutdown();
    }

}

 四、结果

start the computer...~
cpu 启动!
内存 启动!
硬盘 启动!
start the computer finished!
shutdown the computer...~
cup 关闭
内存  关闭
硬盘 关闭
shutdown the computer finished!