java 父类引用指向子类对象

//父类
public class Father{
//父类有一个打孩子方法
    public void hitChild(){
    }
}
//子类1
public class Son1 extends Father{
//重写父类打孩子方法
    public void hitChild(){
        System.out.println("为什么打我？我做错什么了！");
    }
}
//子类2
public class Son2 extends Father{
//重写父类打孩子方法
    public void hitChild(){
        System.out.println("我知道错了，别打了！");
    }
}
//子类3
public class Son3 extends Father{
//重写父类打孩子方法
    public void hitChild(){
        System.out.println("我跑，你打不着！");
    }
}
//测试类
public class Test{
    public static void main(String args[]){
        Father father;
        father = new Son1();
        father.hitChild();
        father = new Son2();
        father.hitChild();
        father = new Son3();
        father.hitChild();
    }
}
//重写父类打孩子方法
    public void hitChild(){
        System.out.println("我跑，你打不着！");
    }
}
//测试类
public class Test{
    public static void main(String args[]){
        Father father;
        father = new Son1();
        father.hitChild();
        father = new Son2();
        father.hitChild();
        father = new Son3();
        father.hitChild();
    }
}

IUser iUser = new RedisUserImpl();
IUser iUser1 = new HbaseUserImpl();