C++使用Protobuf举例

首先安装C++的Protobuf，按官方指导来： https://github.com/protocolbuffers/protobuf/tree/master/src
下载release包，解压后编译安装即可。

用法举例，先定义proto文件：

syntax = "proto3";
package test;

enum Sex {
    BOY = 0;
    GIRL = 1;
}

message Student {
  int32 Id = 1;     // id
  string Name = 2;  // name
  Sex Sex = 3;
}

message Team {
    int32 Id = 1;
    string Name = 2;
    repeated Student Student = 3;
}

然后用protoc生成对应的编解码文件: protoc --cpp_out=. test.proto，cpp_out表示生成cpp的编解码源文件。测试代码：

#include <iostream>
#include <string>
#include "test.pb.h"

using namespace std;
using namespace test;

int main()
{
    Team team;
    team.set_id(1);
    team.set_name("Rocket");
    Student *s1 = team.add_student(); // 添加repeated成员
    s1->set_id(1);
    s1->set_name("Mike");
    s1->set_sex(BOY);
    Student *s2 = team.add_student();
    s2->set_id(2);
    s2->set_name("Lily");
    s2->set_sex(GIRL);

    // encode --> bytes stream
    string out;
    team.SerializeToString(&out);

    // decode --> team structure
    Team t;
    t.ParseFromArray(out.c_str(), out.size()); // or parseFromString
    cout << t.DebugString() << endl;
    for (int i = 0; i < t.student_size(); i++) {
        Student s = t.student(i); // 按索引解repeated成员
        cout << s.name() << " " << s.sex() << endl;
    }

    return 0;
}

编译的时候记得链接protobuf库。Protobuf还是挺好用的。