结构型模式 --- 外观模式

多个子系统对外有统一的接口 不必关心内部具体实现细节 大大降低应用程序的复杂度

// 子系统1
package facade;

public class SubSystem1 {
    public void method() {
        System.out.println("SubSystem1 method");
    }
}

// 子系统2
package facade;

public class SubSystem2 {
    public void method() {
        System.out.println("SubSystem2 method");
    }
}

// 子系统3
package facade;

public class SubSystem3 {
    public void method() {
        System.out.println("SubSystem3 method");
    }
}

// 统一封装对外接口
package facade;

public class Facade {
    private SubSystem1 obj1 = new SubSystem1();
    private SubSystem2 obj2 = new SubSystem2();
    private SubSystem3 obj3 = new SubSystem3();

    public void method() {
        obj1.method();
        obj2.method();
        obj3.method();
    }
}

// 测试类
package facade;

public class Client {
    public static void main(String[] args) {
        Facade facade = new Facade();
        facade.method();
    }
}