23种设计模式-外观模式

1.外观模式

通过对客户端提供一个统一的接口，用于访问子系统中的一群接口

优缺点

优点：

更加易用 松散耦合 更好的划分访问层次

缺点：

对子系统类做太多的限制则减少了可变性和灵活性

使用场景

实现方式

#

public class CPU {

    public void startup(){
        System.out.println("cpu startup!");
    }

    public void shutdown(){
        System.out.println("cpu shutdown!");
    }
}

public class Memory {

    public void startup(){
        System.out.println("memory startup!");
    }

    public void shutdown(){
        System.out.println("memory shutdown!");
    }
}

public class Disk {

    public void startup(){
        System.out.println("disk startup!");
    }

    public void shutdown(){
        System.out.println("disk shutdown!");
    }
}

//Facade类
public class Computer {
    private CPU cpu;
    private Memory memory;
    private Disk disk;

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

    public void startup(){
        System.out.println("start the computer!");
        cpu.startup();
        memory.startup();
        disk.startup();
        System.out.println("start computer finished!");
    }

    public void shutdown(){
        System.out.println("begin to close the computer!");
        cpu.shutdown();
        memory.shutdown();
        disk.shutdown();
        System.out.println("computer closed!");
    }
}

public class User {

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

参考博客：https://blog.csdn.net/a745233700/article/details/83651734