Boost序列化指针

Boost.Serialization 还能序列化指针和引用。 由于指针存储对象的地址，序列化对象的地址没有什么意义，而是在序列化指针和引用时，对象的引用被自动地序列化。

代码

#include <boost/archive/text_oarchive.hpp> 
#include <boost/archive/text_iarchive.hpp> 
#include <iostream> 
#include <sstream> std::stringstream ss; class person 
{ 
public: person() { } person(int age) : age_(age) { } int age() const { return age_; } private: friend class boost::serialization::access; template <typename Archive> void serialize(Archive &ar, const unsigned int version) { ar & age_; } int age_; 
}; void save() 
{ boost::archive::text_oarchive oa(ss); person *p = new person(31); oa << p; std::cout << std::hex << p << std::endl; delete p; 
} void load() 
{ boost::archive::text_iarchive ia(ss); person *p; ia >> p; std::cout << std::hex << p << std::endl; std::cout << p->age() << std::endl; delete p; 
} int main() 
{ save(); load(); 
} 

结果

0x1ff7bd0
0x1ff7830
1f

上面的应用程序创建了一个新的 person 类型的对象，使用 new 创建并赋值给指针 p 。 是指针 - 而不是 *p - 被序列化了。Boost.Serialization 自动地通过 p 的引用序列化对象本身而不是对象的地址。

如果归档被恢复， p 不必指向相同的地址。 而是创建新对象并将它的地址赋值给 p 。 Boost.Serialization 只保证对象和之前序列化的对象相同，而不是地址相同。

由于新式的 C++ 在动态分配内存有关的地方使用 智能指针 (smart pointers) ， Boost.Serialization 对此也提供了相应的支持。

#include <boost/archive/text_oarchive.hpp> 
#include <boost/archive/text_iarchive.hpp> 
#include <boost/serialization/scoped_ptr.hpp> 
#include <boost/scoped_ptr.hpp> 
#include <iostream> 
#include <sstream> std::stringstream ss; class person 
{ 
public: person() { } person(int age) : age_(age) { } int age() const { return age_; } private: friend class boost::serialization::access; template <typename Archive> void serialize(Archive &ar, const unsigned int version) { ar & age_; } int age_; 
}; void save() 
{ boost::archive::text_oarchive oa(ss); boost::scoped_ptr<person> p(new person(31)); oa << p; 
} void load() 
{ boost::archive::text_iarchive ia(ss); boost::scoped_ptr<person> p; ia >> p; std::cout << p->age() << std::endl; 
} int main() 
{ save(); load(); 
} 

例子中使用了智能指针 boost::scoped_ptr 来管理动态分配的 person 类型的对象。 为了序列化这样的指针，必须包含 boost/serialization/scoped_ptr.hpp 头文件。

在使用 boost::shared_ptr 类型的智能指针的时候需要序列化，那么必须包含 boost/serialization/shared_ptr.hpp 头文件。

下面的应用程序使用引用替代了指针。

#include <boost/archive/text_oarchive.hpp> 
#include <boost/archive/text_iarchive.hpp> 
#include <iostream> 
#include <sstream> std::stringstream ss; class person 
{ 
public: person() { } person(int age) : age_(age) { } int age() const { return age_; } private: friend class boost::serialization::access; template <typename Archive> void serialize(Archive &ar, const unsigned int version) { ar & age_; } int age_; 
}; void save() 
{ boost::archive::text_oarchive oa(ss); person p(31); person &pp = p; std::cout<<&p<<std::endl;oa << pp; 
} void load() 
{ boost::archive::text_iarchive ia(ss); person p; person &pp = p; ia >> pp; std::cout <<&p<<" "<<pp.age() << std::endl; 
} int main() 
{ save(); load(); 

输出结果

0x7ffc362e9360
0x7ffc362e9360 31

指针数组

#include <iostream>
#include <fstream>
#include <string>
#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/text_iarchive.hpp>
#include <boost/serialization/vector.hpp>const int ARRAY_SIZE = 3;class SomeType {
public:SomeType() : value(0) {}SomeType(int val) : value(val) {}int getValue() const { return value; }// 添加序列化函数template <class Archive>void serialize(Archive& ar, const unsigned int version) {ar & value;}private:int value;
};class MyClass {friend class boost::serialization::access;public:MyClass() = default;int data;SomeType* pointers[ARRAY_SIZE];template <class Archive>void serialize(Archive& ar, const unsigned int version) {ar & data;for (int i = 0; i < ARRAY_SIZE; ++i) {ar & pointers[i];}}
};int main() {MyClass obj;obj.data = 42;for (int i = 0; i < ARRAY_SIZE; ++i) {obj.pointers[i] = new SomeType(i * 10);}{std::ofstream file("my_class_data.txt");boost::archive::text_oarchive oa(file);oa << obj;}for (int i = 0; i < ARRAY_SIZE; ++i) {delete obj.pointers[i];}MyClass loadedObj;{std::ifstream file("my_class_data.txt");boost::archive::text_iarchive ia(file);ia >> loadedObj;}std::cout << "Loaded Object Data: " << loadedObj.data << std::endl;for (int i = 0; i < ARRAY_SIZE; ++i) {std::cout << loadedObj.pointers[i]->getValue()<< std::endl;delete loadedObj.pointers[i];}return 0;
}