设计模式-外观模式

就是多加了Facade 这一层，让自己同serviceA ServiceB ServiceC
不会直接被调用。

interface ServiceA{
    public void methodA();
}
interface ServiceB{
    public void methodB();
}
interface ServiceC{
    public void methodC();
}

class Facade{
    ServiceA sa;
    ServiceB sb;
    ServiceC sc;

    public Facade(){
        sa= new ServiceAImpl();
        sb= new ServiceBImpl();
        sc= new ServiceCImpl();
    }
    public void methodA(){
        sa.methodA();
        sb.methodB();
    }
    public void methodB(){
        sb.methodB();
        sc.methodC();
    }
    public void methodC(){
        sc.methodC();
        sa.methodA();
    }
}
class ServiceAImpl implements ServiceA{
    public void methodA(){
        System.out.println("A");
    }
}
class ServiceBImpl implements ServiceB{
    public void methodB(){
        System.out.println("B");
    }
}
class ServiceCImpl implements ServiceC{
    public void methodC(){
        System.out.println("C");
    }
}

public class FacadeTest {
    public static void main(String[] args){
        ServiceA sa = new ServiceAImpl();
        ServiceB sb = new ServiceBImpl();

        sa.methodA();
        sb.methodB();

        System.out.println("============");

        Facade facade = new Facade();
        facade.methodA();
        facade.methodB();
    }
}