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相关文献

• Protocol Buffers官网
• C++ Installation官网
• Protocol Buffer Basics: C++
• Download Protocol Buffers（官方用例）
• Documentation » cmake-modules(7) » FindProtobuf

protocol buffers是谷歌的语言中立、平台中立、可扩展的结构化数据序列化机制——XML，但更小、更快、更简单。您可以一次定义数据的结构化方式，然后可以使用特殊生成的源代码轻松地使用各种语言（C++/ C#/ Dart/ Go/ Java/ Kotlin/ Python）在各种数据流中写入和读取结构化数据。

安装

C++ Installation - Unix

最简单的方式：

sudo apt install protobuf-compiler

如果你想使用最新版，安装教程可以参考C++ Installation官网

Protobuf2 0基础上手例子（C++/CMake）

我们使用了官方用例进行构建：Protocol Buffer Basics: C++

首先创建文件addressbook.proto：

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;
}

创建CMakeLists.txt：

# Minimum CMake required
cmake_minimum_required(VERSION 2.8)

# Project
project(Person)

# Find required protobuf package
find_package(Protobuf REQUIRED)
if (PROTOBUF_FOUND)
    message(STATUS "protobuf library found")
else ()
    message(FATAL_ERROR "protobuf library is needed but cant be found")
endif ()

include_directories(${PROTOBUF_INCLUDE_DIRS})
include_directories(${CMAKE_CURRENT_BINARY_DIR})
protobuf_generate_cpp(PROTO_SRCS PROTO_HDRS addressbook.proto)
message(${PROTO_SRCS} ${PROTO_HDRS})
add_executable(Person Person.cpp ${PROTO_SRCS} ${PROTO_HDRS})

target_link_libraries(Person ${PROTOBUF_LIBRARIES})

创建Person.cpp：

#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;
}

在当前目录打开终端并输入：

 cmake ./ && make
 ./Person people.data

这时我们会看到：

于是你输入的数据就会保存在people.data里面

之后我们修改Person.cpp为：

#include 
#include 
#include 
#include "addressbook.pb.h"

using namespace std;

// Iterates though all people in the AddressBook and prints info about them.
void ListPeople(const tutorial::AddressBook &address_book) {
    for (int i = 0; i < address_book.people_size(); i++) {
        const tutorial::Person &person = address_book.people(i);

        cout << "Person ID: " << person.id() << endl;
        cout << "  Name: " << person.name() << endl;
        if (person.has_email()) {
            cout << "  E-mail address: " << person.email() << endl;
        }

        for (int j = 0; j < person.phones_size(); j++) {
            const tutorial::Person::PhoneNumber &phone_number = person.phones(j);

            switch (phone_number.type()) {
                case tutorial::Person::MOBILE:
                    cout << "  Mobile phone #: ";
                    break;
                case tutorial::Person::HOME:
                    cout << "  Home phone #: ";
                    break;
                case tutorial::Person::WORK:
                    cout << "  Work phone #: ";
                    break;
            }
            cout << phone_number.number() << endl;
        }
    }
}

// Main function:  Reads the entire address book from a file and prints all
//   the information inside.
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 (!address_book.ParseFromIstream(&input)) {
            cerr << "Failed to parse address book." << endl;
            return -1;
        }
    }

    ListPeople(address_book);

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

    return 0;
}

在当前目录打开终端并输入：

 cmake ./ && make
 ./Person people.data

这时我们会看到：

Protobuf3 0基础上手例子（C++/CMake）

我们从官网下载最新的Download Protocol Buffers（官方用例）作为例子如下（参考CMake官网Documentation » cmake-modules(7) » FindProtobuf）：

首先创建addressbook.proto：

// See README.txt for information and build instructions.
//
// Note: START and END tags are used in comments to define sections used in
// tutorials.  They are not part of the syntax for Protocol Buffers.
//
// To get an in-depth walkthrough of this file and the related examples, see:
// https://developers.google.com/protocol-buffers/docs/tutorials

// [START declaration]
syntax = "proto3";
package tutorial;

import "google/protobuf/timestamp.proto";
// [END declaration]

// [START java_declaration]
option java_multiple_files = true;
option java_package = "com.example.tutorial.protos";
option java_outer_classname = "AddressBookProtos";
// [END java_declaration]

// [START csharp_declaration]
option csharp_namespace = "Google.Protobuf.Examples.AddressBook";
// [END csharp_declaration]

// [START go_declaration]
option go_package = "../tutorial";
// [END go_declaration]

// [START messages]
message Person {
  string name = 1;
  int32 id = 2;  // Unique ID number for this person.
  string email = 3;

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

  message PhoneNumber {
    string number = 1;
    PhoneType type = 2;
  }

  repeated PhoneNumber phones = 4;

  google.protobuf.Timestamp last_updated = 5;
}

// Our address book file is just one of these.
message AddressBook {
  repeated Person people = 1;
}
// [END messages]

CMakeLists.txt：

# Minimum CMake required
cmake_minimum_required(VERSION 3.8)

# Project
project(protobuf-examples)

# Find required protobuf package
find_package(Protobuf REQUIRED)
if (PROTOBUF_FOUND)
    message(STATUS "protobuf library found")
else ()
    message(FATAL_ERROR "protobuf library is needed but cant be found")
endif ()

set(CMAKE_INCLUDE_CURRENT_DIR TRUE)

# http://www.cmake.org/Wiki/CMake_FAQ#How_can_I_build_my_MSVC_application_with_a_static_runtime.3F
if (MSVC AND protobuf_MSVC_STATIC_RUNTIME)
    foreach (flag_var
            CMAKE_CXX_FLAGS CMAKE_CXX_FLAGS_DEBUG CMAKE_CXX_FLAGS_RELEASE
            CMAKE_CXX_FLAGS_MINSIZEREL CMAKE_CXX_FLAGS_RELWITHDEBINFO)
        if (${flag_var} MATCHES "/MD")
            string(REGEX REPLACE "/MD" "/MT" ${flag_var} "${${flag_var}}")
        endif (${flag_var} MATCHES "/MD")
    endforeach ()
endif ()

foreach (example add_person list_people)
    set(${example}_SRCS ${example}.cc)
    set(${example}_PROTOS addressbook.proto)

    #Code Generation
    if (protobuf_MODULE_COMPATIBLE) #Legacy Support
        protobuf_generate_cpp(${example}_PROTO_SRCS ${example}_PROTO_HDRS ${${example}_PROTOS})
        list(APPEND ${example}_SRCS ${${example}_PROTO_SRCS} ${${example}_PROTO_HDRS})
    endif ()

    #Executable setup
    set(executable_name ${example}_cpp)
    add_executable(${executable_name} ${${example}_SRCS} ${${example}_PROTOS})
    if (protobuf_MODULE_COMPATIBLE) #Legacy mode
        target_include_directories(${executable_name} PUBLIC ${PROTOBUF_INCLUDE_DIRS})
        target_link_libraries(${executable_name} ${PROTOBUF_LIBRARIES})
    else ()
        target_link_libraries(${executable_name} protobuf::libprotobuf)
        protobuf_generate(TARGET ${executable_name})
    endif ()

endforeach ()

add_person.cc

// See README.txt for information and build instructions.

#include 
#include 
#include 
#include 
#include 

#include "addressbook.pb.h"

using namespace std;

using google::protobuf::util::TimeUtil;

// 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;
        }
    }
    *person->mutable_last_updated() = TimeUtil::SecondsToTimestamp(time(NULL));
}

// 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;
}

list_people.cc

// See README.txt for information and build instructions.

#include 
#include 
#include 
#include 

#include "addressbook.pb.h"

using namespace std;

using google::protobuf::util::TimeUtil;

// Iterates though all people in the AddressBook and prints info about them.
void ListPeople(const tutorial::AddressBook &address_book) {
    for (int i = 0; i < address_book.people_size(); i++) {
        const tutorial::Person &person = address_book.people(i);

        cout << "Person ID: " << person.id() << endl;
        cout << "  Name: " << person.name() << endl;
        if (person.email() != "") {
            cout << "  E-mail address: " << person.email() << endl;
        }

        for (int j = 0; j < person.phones_size(); j++) {
            const tutorial::Person::PhoneNumber &phone_number = person.phones(j);

            switch (phone_number.type()) {
                case tutorial::Person::MOBILE:
                    cout << "  Mobile phone #: ";
                    break;
                case tutorial::Person::HOME:
                    cout << "  Home phone #: ";
                    break;
                case tutorial::Person::WORK:
                    cout << "  Work phone #: ";
                    break;
                default:
                    cout << "  Unknown phone #: ";
                    break;
            }
            cout << phone_number.number() << endl;
        }
        if (person.has_last_updated()) {
            cout << "  Updated: " << TimeUtil::ToString(person.last_updated()) << endl;
        }
    }
}

// Main function:  Reads the entire address book from a file and prints all
//   the information inside.
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 (!address_book.ParseFromIstream(&input)) {
            cerr << "Failed to parse address book." << endl;
            return -1;
        }
    }

    ListPeople(address_book);

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

    return 0;
}

在当前目录打开终端并输入：

cmake ./ && make
./add_person_cpp people.data

这时我们会看到：

之后我们输入：

./list_people_cpp people.data

这时我们会看到：