外观模式

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



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


public class Disk {
    public void startup(){
        System.out.println("磁盘启动");
    }
    public void shutdown(){
        System.out.println("磁盘关闭");
    }
}



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("电脑启动开始");
        cpu.startup();
        memory.startup();
        disk.startup();
        System.out.println("电脑启动完成");
    }
    public void shutdown(){
        System.out.println("电脑关闭开始");
        cpu.shutdown();
        memory.shutdown();
        disk.shutdown();
        System.out.println("电脑关闭完成");
    }
}

public class Test {
    public static void main(String[] args) {
        Computer computer = new Computer();
        computer.startup();
        System.out.println("======================");
        computer.shutdown();

    }
}