C++ I/O流重载:如何实现友元重载，对于同一标头中相同的4个i/o函数的3个不同的类？

class Base {
public:
    friend ostream& operator<<(ostream& os, const Base& obj);
    friend istream& operator>>(istream& is, Base& obj);
    friend ofstream& operator<<(ofstream& ofs, const Base& obj);
    friend ifstream& operator>>(ifstream& ifs, Base& obj);
};

class Derived1 : public Base {
public:
    friend ostream& operator<<(ostream& os, const Derived1& obj);
    friend istream& operator>>(istream& is, Derived1& obj);
    friend ofstream& operator<<(ofstream& ofs, const Derived1& obj);
};

class Derived2 : public Base {
public:
    friend ostream& operator<<(ostream& os, const Derived2& obj);
    friend istream& operator>>(istream& is, Derived2& obj);
    friend ifstream& operator>>(ifstream& ifs, Derived2& obj);
};

class Derived3 : public Base {
public:
    friend ostream& operator<<(ostream& os, const Derived3& obj);
    friend ofstream& operator<<(ofstream& ofs, const Derived3& obj);
    friend ifstream& operator>>(ifstream& ifs, Derived3& obj);
};

ostream& operator<<(ostream& os, const Derived1& obj) {
    // 实现输出操作
    return os;
}

istream& operator>>(istream& is, Derived1& obj) {
    // 实现输入操作
    return is;
}

// 其他函数的实现类似