在C++中关于protobuf的问题使用

news/2024/4/19 0:59:29/文章来源:https://blog.csdn.net/qq_38156743/article/details/130387629

第一次接触这个玩意，正在记录，本人的系统是ubuntu20.04。

0 首先进行安装这个编译器

1安装 protobuf

打开终端，输入以下命令来安装 protobuf：

sudo apt-get update
sudo apt-get install protobuf-compiler libprotobuf-dev
查看是不是安装成功了
protoc --version
如果出现这个
libprotoc 3.6.1  数字表述版本号

2安装好了后进行数据格式的定义

创建一个文件

touch addressbook.proto

在这个文本中输入下面的代码，保存

// [START declaration]
syntax = "proto3";
package tutorial;import "google/protobuf/timestamp.proto";
// [END 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]

3 对上述文件进行编译

protoc -I=. --cpp_out=. addressbook.proto

在当前目录下进行编译，会生成两个文件一个.cc一个.h文件。

4重新创建一个文件testwrite.cc

#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;// 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;
}

5.1如果你不是在IDE下进行编译的就直接G++编译

g++ testwrite.cc addressbook.pb.cc -o testwrite -lprotobuf -lthread
生成一个testwrite文件，可以进行运行。

5.2运行命令

./testwrite addressbook.data
后面跟着这个addressbook.data意思是创建一个addressbook.data这样的二进制文件，进行数据储存。
运行后进行数据的写入，写入的内容就是你刚才定义的那个数据格式。
全部写完后结束。

6 下面进行读取刚才写入的数据

创建一个代码读的代码
touch testread.cc

#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;// 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;
}

7创建完了进行编译直接G++编译

g++ testread.cc addressbook.pb.cc -o testwrite -lprotobuf -lthread

8然后运行

./testread addressbook.data

就会打印出来你刚才的数据。

*******如果用IDE的就添加CMakeLists.txt

cmake_minimum_required(VERSION 3.1)set(CMAKE_CXX_STANDARD 14)
project(write)include_directories(${CMAKE_CURRENT_SOURCE_DIR})add_executable(write testwrite.cpp testread.cpp addressbook.pb.cc addressbook.pb.h )target_link_libraries(write PRIVATE protobuf pthread)