1.代码

实例1

addressbook.proto

syntax = "proto3";

package tutorial;

message Person {
  string name = 1;
  string email = 2;
}

message AddressBook {
  repeated Person people = 1;
}

1_addressbook_protobuf实例.cc

#include <iostream>
#include <fstream>
#include <string>
#include "addressbook.pb.h"

void WriteAddressBook()
{
    tutorial::AddressBook address_book;

    // 添加一个 Person
    tutorial::Person *person = address_book.add_people();
    person->set_name("Alice");
    person->set_email("alice@example.com");

    // 写入到文件
    std::ofstream output("addressbook.data", std::ios::binary);
    if (!address_book.SerializeToOstream(&output))
    {
        std::cerr << "Failed to write address book." << std::endl;
        return;
    }
}

void ReadAddressBook()
{
    tutorial::AddressBook address_book;

    // 从文件读取
    std::ifstream input("addressbook.data", std::ios::binary);
    if (!address_book.ParseFromIstream(&input))
    {
        std::cerr << "Failed to read address book." << std::endl;
        return;
    }

    // 输出读取到的人名
    for (int i = 0; i < address_book.people_size(); ++i)
    {
        const tutorial::Person &person = address_book.people(i);
        std::cout << "Name: " << person.name() << ", Email: " << person.email() << std::endl;
    }
}

int main()
{
    WriteAddressBook();
    ReadAddressBook();
    return 0;
}

实例2

person.proto

syntax = "proto3";  // 使用Protocol Buffers v3语法

package example;  // 定义包名，便于组织和避免命名冲突

message Person {  // 定义名为Person的消息类型
  string name = 1;  // 字符串类型字段，标签为1
  int32 id = 2;    // 整型字段，标签为2
  bool is_active = 3;  // 布尔型字段，标签为3
  repeated string email = 4;  // 重复字段，表示字符串列表，标签为4
}

2_protobuf_person_序列号到字节.cc

#include "person.pb.h"
#include <fstream>
#include <iostream>
#include <stdint.h>
#include <vector>
using namespace std;

// 写入文件
void WriteToFile(const std::string& filename, const example::Person& person) {
  std::fstream output(filename, std::ios::out | std::ios::trunc | std::ios::binary);
  if (!person.SerializeToOstream(&output)) {
    std::cerr << "Failed to write person." << std::endl;
  }
}

// 从文件读取
void ReadFromFile(const std::string& filename, example::Person& person) {
  std::fstream input(filename, std::ios::in | std::ios::binary);
  if (!person.ParseFromIstream(&input)) {
    std::cerr << "Failed to parse person." << std::endl;
  }
}

// 打印反序列化后的数据
void PrintPerson(const example::Person& person) {
  std::cout << "Name: " << person.name() << std::endl;
  std::cout << "ID: " << person.id() << std::endl;
  std::cout << "Is Active: " << person.is_active() << std::endl;
  // 打印反序列化后的数据
  for (int i = 0; i < person.email_size(); ++i) {
    std::cout << "Email " << i + 1 << ": " << person.email(i) << std::endl;
  }
}

int main() {
  // 创建并填充一个Person对象
  example::Person person;
  person.set_name("Alice");
  person.set_id(123);
  person.set_is_active(true);
  person.add_email("alice@example.com");
  person.add_email("alice.personal@gmail.com");

  // 1.序列化到 字节
  uint8_t buf[256] = { 0 };
  bool ret = person.SerializeToArray(buf, sizeof(buf));

  // 2.反序列化从 字节
  example::Person new_person;
  ret = new_person.ParseFromArray(buf, sizeof(buf));

  cout << "result ret: " << ret << endl;
  PrintPerson(new_person);

  // 3.读写probuf测试
  WriteToFile("person.bin", person);  // 写入文件
  ReadFromFile("person.bin", new_person); // 从文件读取
  PrintPerson(new_person);            // 打印反序列化后的数据

  return 0;
}

2.scons编译

SConstruct

import os
## 模板2
env = Environment()
env["PROGSUFFIX"] = ".out"            # 可执行后缀.out
env["CCFLAGS"] = " -g3 -O0 -Wall"       # gdb 调试开关
# -pthread -lprotobuf
env.MergeFlags(["!pkg-config protobuf --cflags --libs"])

def build_protobuf(file_path):
    file,file_ext = os.path.splitext(file_path)
    print(file,file_ext)
    if file_ext != ".proto":
        raise f"{file_path} not .proto file"
    cmd=f"protoc --cpp_out=. {file}.proto"
    Command(f"{file}.pb.h",file_path,cmd)

build_protobuf("addressbook.proto")
env.Program(Split("1_addressbook_protobuf实例.cc addressbook.pb.cc"))
build_protobuf("person.proto")
env.Program(Split("2_protobuf_person_序列号到字节.cc person.pb.cc"))

注意:
protobuf编译方法
protoc --cpp_out=. addressbook.proto

生成 addressbook.pb.cc addressbook.pb.h

scons中并没有直接构建protobuf方法, 可以使用scons Command(target_file, src_file, cmd)
Command使用说明: 如果src_file 时间戳比 target_file 新, 则执行cmd命令
示例: Command("addressbook.pb.h", "addressbook.proto", "rotoc --cpp_out=. addressbook.proto")

---

scons

scons: Reading SConscript files …
addressbook .proto
person .proto
scons: done reading SConscript files.
scons: Building targets …
protoc --cpp_out=. addressbook.proto
g++ -o 1_addressbook_protobuf实例.o -c -g3 -O0 -Wall -pthread 1_addressbook_protobuf实例.cc
g++ -o addressbook.pb.o -c -g3 -O0 -Wall -pthread addressbook.pb.cc
g++ -o 1_addressbook_protobuf实例.out -pthread 1_addressbook_protobuf实例.o addressbook.pb.o -lprotobuf
protoc --cpp_out=. person.proto
g++ -o 2_protobuf_person_序列号到字节.o -c -g3 -O0 -Wall -pthread 2_protobuf_person_序列号到字节.cc
g++ -o person.pb.o -c -g3 -O0 -Wall -pthread person.pb.cc
g++ -o 2_protobuf_person_序列号到字节.out -pthread 2_protobuf_person_序列号到字节.o person.pb.o -lprotobuf
scons: done building targets.

3.验证测试

./1_addressbook_protobuf实例.out

Name: Alice, Email: alice@example.com

./2_protobuf_person_序列号到字节.out

result ret: 0
Name: Alice
ID: 123
Is Active: 1
Email 1: alice@example.com
Email 2: alice.personal@gmail.com
Name: Alice
ID: 123
Is Active: 1
Email 1: alice@example.com
Email 2: alice.personal@gmail.com