protobuf c++例子

1, people.proto 

package demo;

message People {
  required string name = 1;
  required int32 id = 2;
  required string email = 3;
}

2, 生成stub类 

protoc --cpp_out=. people.proto
rprotoc people.proto

3, C++服务器端server.cc 

#include <stdio.h>
#include <stdlib.h>
#include <strings.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string>
#include <iostream>
#include "people.pb.h"

#define PORT 8888
#define MAXDATASIZE 20
#define BACKLOG 10

using namespace std;

int main()
{
  int listenfd, connectfd, numbytes;
  char buf[MAXDATASIZE];
  struct sockaddr_in server;
  struct sockaddr_in client;
  int sin_size;

  listenfd = socket(AF_INET, SOCK_STREAM, 0);

  int opt = SO_REUSEADDR;
  setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

  bzero(&server, sizeof(server));
  server.sin_family = AF_INET;
  server.sin_port = htons(PORT);
  server.sin_addr.s_addr = htonl(INADDR_ANY);

  bind(listenfd, (struct sockaddr *)&server, sizeof(struct sockaddr));

  listen(listenfd,BACKLOG);

  while(1){
    sin_size = sizeof(struct sockaddr_in);

    connectfd = accept(listenfd, (struct sockaddr *)&client, &sin_size);

    numbytes = recv(connectfd, buf, MAXDATASIZE, 0);
    buf[numbytes] = '\0';
    string a = buf;
    cout << "You got a message from " << inet_ntoa(client.sin_addr) << endl;
    cout << "Client Message: " << a << endl;
    if(a == "GET PEOPLE") {
      string data;
      demo::People p;
      p.set_name("Hideto");
      p.set_id(123);
      p.set_email("hideto.bj@gmail.com");
      p.SerializeToString(&data);
      char bts[data.length()];
      strcpy(bts, data.c_str());
      send(connectfd, bts, sizeof(bts), 0);
    } else {
      send(connectfd, "Fucking client!\n", 16, 0);
    }
    close(connectfd);
  }

  close(listenfd);
  return 0;
}

4, C++客户端client.cc 

#include <stdio.h>
#include <unistd.h>
#include <strings.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <string>
#include <iostream>
#include "people.pb.h"

#define HOST "localhost"
#define PORT 8888
#define MAXDATASIZE 100

using namespace std;

int main(int argc, char ** argv)
{
  int fd, numbytes;
  char buf[MAXDATASIZE];
  struct hostent *he;
  struct sockaddr_in server;

  if (argc != 2) {
    printf("Usage: %s \"COMMAND\"\n",argv[0]);
    exit(0);
  }

  he = gethostbyname(HOST);
  fd = socket(AF_INET, SOCK_STREAM, 0);
  bzero(&server, sizeof(server));
  server.sin_family = AF_INET;
  server.sin_port = htons(PORT);
  server.sin_addr = *((struct in_addr *)he->h_addr);

  connect(fd, (struct sockaddr *)&server, sizeof(struct sockaddr));

  send(fd, argv[1], 20, 0);

  numbytes = recv(fd, buf, MAXDATASIZE, 0);
  buf[numbytes] = '\0';
  string data = buf;
  demo::People p;
  p.ParseFromString(data);
  cout << "People: " << endl;
  cout << "Name: " << p.name() << endl;
  cout << "ID: " << p.id() << endl;
  cout << "Email: " << p.email() << endl;

  close(fd);
  return 0;
}

5, Ruby客户端client.rb 

require 'socket'
require 'people.pb.rb'

HOST = "localhost"
PORT = 8888

client = TCPSocket.open(HOST, PORT)
client.send("GET PEOPLE", 0)
client.close_write
s = client.read
p = Demo::People.new
p.parse_from_string s
p p

6, 使用g++编译 

$ g++ server.cc people.pb.cc -o s -lprotobuf
$ g++ client.cc people.pb.cc -o c -lprotobuf

7, 运行 

#启动server
./s

You got a message from 127.0.0.1
Client Message: GET PEOPLE
You got a message from 127.0.0.1
Client Message: GET PEOPLE

#运行c++的client
./c "GET PEOPLE"

People:
Name: Hideto
ID: 123
Email: hideto.bj@gmail.com


#运行Ruby的client
ruby client.rb

name: "Hideto"
id: 123
email: "hideto.bj@gmail.com"