protobuf使用

TheLudGamer · 发表于 2023-2-25 16:34

1. 概述

Protocol Buffers(又名protobuf) 是一种语言中立、平台中立的可扩展机制，用于序列化结构化的数据
它就像JSON，只是它更小、更快
只需定义一次数据如何被结构化，然后就可以使用特殊生成的源代码，轻松地从各种数据流和使用各种语言写入和读取结构化数据
2. 好处

protobuf适配多种语言，可以很方便的序列化结构化的数据，最常被用于定义通信协议(与gRPC一起)和数据存储
使用protobuf的一些优点：

3. 示例(Python)

我们创建一个非常简单的“地址簿”应用程序，它可以在文件之间读取和写入人们的联系信息
通讯簿中的每个人都有一个姓名、一个 ID、一个电子邮件地址和一个联系电话号码
3.1 定义协议格式

创建addressbook.proto
syntax = "proto2";package tutorial;message Person { optional string name = 1; optional int32 id = 2; optional string email = 3; enum PhoneType { MOBILE = 0; HOME = 1; WORK = 2; } message PhoneNumber { optional string number = 1; optional PhoneType type = 2 [default = HOME]; } repeated PhoneNumber phones = 4;}message AddressBook { repeated Person people = 1;}
proto文件以包声明开始，这有助于防止不同项目之间的命名冲突
每个元素上的"= 1"，" = 2" 标记标识字段在二进制编码中使用的唯一“标记”

每个字段必须使用下列修饰符之一进行注释:

3.2 编译Protocol Buffers

a) 安装编译器
b) 运行
$ protoc --python_out=./ addressbook.proto
因为需要 Python 类，所以可以使用 --python_out
这将在指定的目标目录中生成 addressbook_pb2.py
3.3 写数据

#! /usr/bin/pythonimport addressbook_pb2import sys# This function fills in a Person message based on user input.def PromptForAddress(person): person.id = int(raw_input("Enter person ID number: ")) person.name = raw_input("Enter name: ") email = raw_input("Enter email address (blank for none): ") if email != "": person.email = email while True: number = raw_input("Enter a phone number (or leave blank to finish): ") if number == "": break phone_number = person.phones.add() phone_number.number = number type = raw_input("Is this a mobile, home, or work phone? ") if type == "mobile": phone_number.type = addressbook_pb2.Person.MOBILE elif type == "home": phone_number.type = addressbook_pb2.Person.HOME elif type == "work": phone_number.type = addressbook_pb2.Person.WORK else: print "Unknown phone type; leaving as default value."# Main procedure: Reads the entire address book from a file,# adds one person based on user input, then writes it back out to the same# file.if len(sys.argv) != 2: print "Usage:", sys.argv[0], "ADDRESS_BOOK_FILE" sys.exit(-1)address_book = addressbook_pb2.AddressBook()# Read the existing address book.try: f = open(sys.argv[1], "rb") address_book.ParseFromString(f.read()) f.close()except IOError: print sys.argv[1] + ": Could not open file. Creating a new one."# Add an address.PromptForAddress(address_book.people.add())# Write the new address book back to disk.f = open(sys.argv[1], "wb")f.write(address_book.SerializeToString())f.close()3.4 读数据

#! /usr/bin/pythonimport addressbook_pb2import sys# Iterates though all people in the AddressBook and prints info about them.def ListPeople(address_book): for person in address_book.people: print "Person ID:", person.id print " Name:", person.name if person.HasField('email'): print " E-mail address:", person.email for phone_number in person.phones: if phone_number.type == addressbook_pb2.Person.PhoneType.MOBILE: print " Mobile phone #: ", elif phone_number.type == addressbook_pb2.Person.PhoneType.HOME: print " Home phone #: ", elif phone_number.type == addressbook_pb2.Person.PhoneType.WORK: print " Work phone #: ", print phone_number.number# Main procedure: Reads the entire address book from a file and prints all# the information inside.if len(sys.argv) != 2: print "Usage:", sys.argv[0], "ADDRESS_BOOK_FILE" sys.exit(-1)address_book = addressbook_pb2.AddressBook()# Read the existing address book.f = open(sys.argv[1], "rb")address_book.ParseFromString(f.read())f.close()ListPeople(address_book)

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