protobuf的应用

1.版本和引用

syntax = "proto3";    // proto2
package tutorial;     // package类似C++命名空间
// 可以引用本地的，也可以引用include里面的
import "google/protobuf/timestamp.proto";   // 已经写好的proto文件是可以引用

我们版本选择proto3  引用的是谷歌的protobuf包

2.如何编译

//protoc -I=/路径1 --cpp_out=./路径2 /路径1/addressbook.proto
//路径1为.proto所在的路径
//路径2为.cc和.h生成的位置
//将指定proto文件生成.pb.cc和.pb.h
//protoc -I=./ --cpp_out=./ addressbook.proto
//将对应目录的所有proto文件生成.pb.cc和.pb.h
//protoc -I=./ --cpp_out=./ *.proto

我们通过上述编译代码可以生成.pb.cc和.pb.h的文件 提供给我们c/c++开发语言使用使用

3.版本号选择

// [START java_declaration]
option java_package = "com.example.tutorial";
option java_outer_classname = "AddressBookProtos";
// [END java_declaration]// [START csharp_declaration]
option csharp_namespace = "Google.Protobuf.Examples.AddressBook";
// [END csharp_declaration]

我们可以选择java和C#的版本来使用protobuf包

4.主体内容

// 通讯录
// [START messages]  
message Person {    // message类似C++的classstring name   = 1;  // 名字int32 id      = 2;  // Unique ID number for this person. 每个人的唯一idstring email  = 3;enum PhoneType {    // enum 枚举类型MOBILE = 0;HOME = 1;WORK = 2;}message PhoneNumber {string number = 1;    // 字符串 电话号码PhoneType type = 2;   //}repeated PhoneNumber phones = 4;    // 重复0~多个，一个人有多个电话google.protobuf.Timestamp last_updated = 5; // import "google/protobuf/timestamp.proto"
}// Our address book file is just one of these.
message AddressBook {repeated Person people = 1;   // 电话簿有多人的电话
}
// [END messages]

类似于C++创建类的方法

5.代码案例

// See README.txt for information and build instructions.#include <ctime>
#include <fstream>
#include <google/protobuf/util/time_util.h>
#include <iostream>
#include <string>#include "addressbook.pb.h"using namespace std;using google::protobuf::util::TimeUtil;// 添加人联系
// 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)); // 设置时间
}
// 正确方式 g++ -std=c++11 -o add_person add_person.cc addressbook.pb.cc -lprotobuf  -lpthread
// 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.  本地文件保存电话本的数据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.  address_book.add_people() 新建一个对象PersonPromptForAddress(address_book.add_people());{// Write the new address book back to disk.  保存电话本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;
}

6.结果展示

输入

输出