protobuf 文档

c++ protobuf 使用教程protocol-buffers c++ tutorialhttps://developers.google.com/protocol-buffers/docs/cpptutorialc++ protoc编译器与protobuf库编译
protoc installProtocol Buffers - Google's data interchange format - protobuf/README.md at master · protocolbuffers/protobufhttps://github.com/protocolbuffers/protobuf/blob/master/src/README.md

With protocol buffers, you write a .proto description of the data structure you wish to store. From that, the protocol buffer compiler creates a class that implements automatic encoding and parsing of the protocol buffer data with an efficient binary format. The generated class provides getters and setters for the fields that make up a protocol buffer and takes care of the details of reading and writing the protocol buffer as a unit. importantly, the protocol buffer format supports the idea of extending the format over time in such a way that the code can still read data encoded with the old format.

.proto 文件example与语法介绍

syntax = "proto2";

package tutorial;


message Person {

  optional string name = 1;
  optional int32 id = 2;
  optional string email = 3;

  enum PhoneType {
    MOBILE = 0;
    HOME = 1;
    WORK = 2;
  }

  message PhoneNumber {
    optional string number = 1;
    optional PhoneType type = 2 [default = HOME];
  }

  repeated PhoneNumber phones = 4;


}

message AddressBook {
  repeated Person people = 1;
}

protoc -I=$SRC_DIR --cpp_out=$DST_DIR $SRC_DIR/addressbook.proto

执行命令后生成如下两个文件，两个1000行的文件

addressbook.pb.h, the header which declares your generated classes. a class for each message you specified in addressbook.proto.
addressbook.pb.cc, which contains the implementation of your classes.

官网示例代码，写通讯录文件

#include 
#include 
#include 
#include "addressbook.pb.h"
using namespace std;

// This function fills in a Person message based on user input.
void promptForAddress(tutorial::Person* person) {
  cout << "Enter person ID number: ";
  int id;
  cin >> id;
  person->set_id(id);
  cin.ignore(256, 'n');

  cout << "Enter name: ";
  getline(cin, *person->mutable_name());

  cout << "Enter email address (blank for none): ";
  string email;
  getline(cin, email);
  if (!email.empty()) {
    person->set_email(email);
  }

  while (true) {
    cout << "Enter a phone number (or leave blank to finish): ";
    string number;
    getline(cin, number);
    if (number.empty()) {
      break;
    }

    tutorial::Person::PhoneNumber* phone_number = person->add_phones();
    phone_number->set_number(number);

    cout << "Is this a mobile, home, or work phone? ";
    string type;
    getline(cin, type);
    if (type == "mobile") {
      phone_number->set_type(tutorial::Person::MOBILE);
    } else if (type == "home") {
      phone_number->set_type(tutorial::Person::HOME);
    } else if (type == "work") {
      phone_number->set_type(tutorial::Person::WORK);
    } else {
      cout << "Unknown phone type.  Using default." << endl;
    }
  }
}

// Main function:  Reads the entire address book from a file,
//   adds one person based on user input, then writes it back out to the same
//   file.
int main(int argc, char* argv[]) {
  // Verify that the version of the library that we linked against is
  // compatible with the version of the headers we compiled against.
  GOOGLE_PROTOBUF_VERIFY_VERSION;

  if (argc != 2) {
    cerr << "Usage:  " << argv[0] << " ADDRESS_BOOK_FILE" << endl;
    return -1;
  }

  tutorial::AddressBook address_book;

  {
    // Read the existing address book.
    fstream input(argv[1], ios::in | ios::binary);
    if (!input) {
      cout << argv[1] << ": File not found.  Creating a new file." << endl;
    } else if (!address_book.ParseFromIstream(&input)) {
      cerr << "Failed to parse address book." << endl;
      return -1;
    }
  }

  // Add an address.
  promptForAddress(address_book.add_people());

  {
    // Write the new address book back to disk.
    fstream output(argv[1], ios::out | ios::trunc | ios::binary);
    if (!address_book.SerializeToOstream(&output)) {
      cerr << "Failed to write address book." << endl;
      return -1;
    }
  }

  // Optional:  Delete all global objects allocated by libprotobuf.
  google::protobuf::ShutdownProtobufLibrary();

  return 0;
}

编译过程

Compiling dependent packages

To compile a package that uses Protocol Buffers, you need to pass various flags to
your compiler and linker. As of version 2.2.0, Protocol Buffers integrates with 
pkg-config to manage this. If you have pkg-config installed, then you can invoke
it to get a list of flags like so:

pkg-config --cflags protobuf         # print compiler flags
pkg-config --libs protobuf           # print linker flags
pkg-config --cflags --libs protobuf  # print both
For example:

c++ my_program.cc my_proto.pb.cc `pkg-config --cflags --libs protobuf`

本例的编译命令

pkg-config 命令需要指定protobuf.pc文件所在目录，默认编译生成a.out

export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig

g++ writer.cpp addressbook.pb.cc `pkg-config --cflags --libs protobuf` -o writer.bin
g++ reader.cpp addressbook.pb.cc `pkg-config --cflags --libs protobuf` -o reader.bin

writer.bin test.address 写入通讯录

reader.bin test.address 读取通讯录内容(可以从官方c++ protobuf教程中获取)