起因：
为了解决类与类之家的依赖关系,降低类类之间的耦合度
代码：
类类
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!");
}
}
外观
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!");
}
}
使用
public class User {
public static void main(String[] args) {
Computer computer = new Computer();
computer.startup();
computer.shutdown();
}
}
想法：
类类(cpu等。。)间的联系是通过外观者(computer)联系协调的，他们之间没直接联系，各自只需要处理好各自的工作即可。
