public static void main(String[] args) {
        Context context;
        
        //ոյʱһ
        System.out.println("-----------------յʱ,һ--------------------\n");
        context = new Context(new BackDoor());//õ
        context.operate();//ִ
        System.out.println("\n");
        
        //ֲ˼ˣڶ
        System.out.println("-----------------ֲ˼ˣڶ-------------------\n");
        context = new Context(new GivenGreenLight());//õ
        context.operate();//ִ˵ڶ
        System.out.println("\n");
        
        //ȨС׷ˣզ죿
        System.out.println("-----------------ȨС׷ˣզ죿-------------\n");
        context = new Context(new BlockEnemy());
        context.operate(); //˱
        System.out.println("\n");
    }