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serialize and deserialize a class in cpp
Guide
how to serialize string
size + data
with ostream/istream
native way with ostream/istream for example class MyClass with height,width,name fields.
class MyClass {
public:
int height;
int width;
std::string name;
}
std::ostream& MyClass::serialize(std::ostream &out) const {
out << height;
out << ',' //number seperator
out << width;
out << ',' //number seperator
out << name.size(); //serialize size of string
out << ',' //number seperator
out << name; //serialize characters of string
return out;
}
std::istream& MyClass::deserialize(std::istream &in) {
if (in) {
int len=0;
char comma;
in >> height;
in >> comma; //read in the seperator
in >> width;
in >> comma; //read in the seperator
in >> len; //deserialize size of string
in >> comma; //read in the seperator
if (in && len) {
std::vector<char> tmp(len);
in.read(tmp.data() , len); //deserialize characters of string
name.assign(tmp.data(), len);
}
}
return in;
}
overload for operator<< and operator>>
std::ostream& operator<<(std::ostream& out, const MyClass &obj)
{
obj.serialize(out);
return out;
}
std::istream& operator>>(std::istream& in, MyClass &obj)
{
obj.deserialize(in);
return in;
}
with boost serialization
archive file format
- text: text_iarchive,text_oarchive
field - xml: xml_iarchive,xml_oarchive, with
BOOST_SERIALIZATION_NVP(field) - binary: binary_iarchive,binary_oarchive with
stringstreamorfstream.
text archive
change BOOST_SERIALIZATION_NVP(field) to field
xml archive
#include <boost/archive/text_iarchive.hpp>
#include <boost/archive/text_oarchive.hpp>
#include <boost/archive/xml_iarchive.hpp>
#include <boost/archive/xml_oarchive.hpp>
#include <boost/archive/binary_iarchive.hpp>
#include <boost/archive/binary_oarchive.hpp>
#include <iostream>
#include <fstream>
#include <sstream>
class Camera {
public:
int id;
std::string name;
double pos;
};
namespace boost {
namespace serialization {
template<class Archive>
void serialize(Archive& archive, Camera& cam, const unsigned int version)
{
archive & BOOST_SERIALIZATION_NVP(cam.id);
archive & BOOST_SERIALIZATION_NVP(cam.name);
archive & BOOST_SERIALIZATION_NVP(cam.pos);
}
} // namespace serialization
} // namespace boost
std::ostream& operator<<(std::ostream& cout, const Camera& cam)
{
cout << cam.id << std::endl
<< cam.name << std::endl
<< cam.pos << std::endl;
return cout;
}
void save()
{
std::ofstream file("archive.xml");
boost::archive::xml_oarchive oa(file);
Camera cam;
cam.id = 100;
cam.name = "new camera";
cam.pos = 99.88;
oa & BOOST_SERIALIZATION_NVP(cam);
}
void load()
{
std::ifstream file("archive.xml");
boost::archive::xml_iarchive ia(file);
Camera cam;
ia & BOOST_SERIALIZATION_NVP(cam);
std::cout << cam << std::endl;
}
void test_camera()
{
save();
load();
}
int main(int argc, char** argv)
{
test_camera();
}
binary archive
void save_load_with_binary_archive()
{
// binary archive with stringstream
std::ostringstream oss;
boost::archive::binary_oarchive oa(oss);
Camera cam;
cam.id = 100;
cam.name = "new camera";
cam.pos = 99.88;
oa & (cam);
# get binary content
std::string str_data = oss.str();
std::cout << str_data << std::endl;
std::istringstream iss(str_data);
boost::archive::binary_iarchive ia(iss);
Camera new_cam;
ia & (new_cam);
std::cout << new_cam << std::endl;
}
binary archive with poco SocketStream
client.cpp
void test_client()
{
SocketAddress address("127.0.0.1", 9911);
StreamSocket socket(address);
SocketStream stream(socket);
//Poco::StreamCopier::copyStream(stream, std::cout);
boost::archive::binary_oarchive oa(stream);
Camera cam;
cam.id = 100;
cam.name = "new camera";
cam.pos = 99.88;
oa & (cam);
}
server.cpp
void run()
{
Application& app = Application::instance();
app.logger().information("Request from " + this->socket().peerAddress().toString());
try
{
SocketStream stream(this->socket());
//Poco::StreamCopier::copyStream(stream, std::cout);
boost::archive::binary_iarchive ia(stream);
Camera new_cam;
ia & (new_cam);
std::cout << new_cam << std::endl;
}
catch (Poco::Exception& exc)
{
app.logger().log(exc);
}
}
notes on std::string
Even know you have seen that they do the same, or that .data() calls .c_str(), it is not correct to assume that this will be the case for other compilers. It is also possible that your compiler will change with a future release.
2 reasons to use std::string:
std::string can be used for both text and arbitrary binary data.
//Example 1
//Plain text:
std::string s1;
s1 = "abc";
s1.c_str();
//Example 2
//Arbitrary binary data:
std::string s2;
s2.append("a\0b\0b\0", 6);
s2.data();
boost archive style
intrusive
private template<class Archive> void serialize(Archive& archive, const unsigned int version)friend class boost::serialization::access;
class Camera {
public:
int id;
std::string name;
double pos;
private:
friend class boost::serialization::access;
template<class Archive>
void serialize(Archive& archive, const unsigned int version)
{
archive & BOOST_SERIALIZATION_NVP(id);
archive & BOOST_SERIALIZATION_NVP(name);
archive & BOOST_SERIALIZATION_NVP(pos);
}
};
non-intrusive
class Camera {
public:
int id;
std::string name;
double pos;
};
namespace boost {
namespace serialization {
template<class Archive>
void serialize(Archive& archive, Camera& cam, const unsigned int version)
{
archive & BOOST_SERIALIZATION_NVP(cam.id);
archive & BOOST_SERIALIZATION_NVP(cam.name);
archive & BOOST_SERIALIZATION_NVP(cam.pos);
}
} // namespace serialization
} // namespace boost
boost archive type
shared_ptr
boost::shared_ptr<T> instead of std::shared_prt<T>
and
#include <boost/serialization/shared_ptr.hpp>
Reference
- serializing-a-class-which-contains-a-stdstring
- is-it-possible-to-serialize-and-deserialize-a-class-in-c
- boost serialization
- boost serialization demo
- ibm boostserialization
- fast-data-image-transfer-server-client-using-boost-asio
History
- 20180128: created.
- 20180129: add intrusive,non-intrusive part.
Copyright
- Post author: kezunlin
- Post link: https://kezunlin.me/post/6887a6ee/
- Copyright Notice: All articles in this blog are licensed under CC BY-NC-SA 3.0 unless stating additionally.