Python使用protobuf极简例子

下载安装

首先，可以直接到protobuf官网阅读学习，到protobuf的github下载编译器。对于非c++用户，直接到github release下载编译好的二进制文件，如果是windows，可以直接下载这个包，然后把bin/protoc.exe放到工作目录。

编译proto文件

目录下新建一个addressbook.proto文件，来自官网的例子（略减）：

syntax = "proto3";
package tutorial;

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;

}

message AddressBook {
  repeated Person people = 1;
}

然后运行protoc.exe：

protoc --python_out=./ addressbook.proto

就直接在当前目录生成了一个addressbook_pb2.py。

测试

先安装一下protocbuf模块，这不必多解释：

pip install protobuf

新建一个add_person.py，也是来自官网的例子（略改）：

import addressbook_pb2
import sys


def PromptForAddress(person):
    """For enter personal infomations"""
    person.id = int(input('Enter ID:'))
    person.name = input('Enter name:')

    email = input('Enter email:')
    if email:
        person.email = email

    while True:
        number = input('Enter phone number (or leave blank to finish):')
        if not number:
            break

        phone_number = person.phones.add()
        phone_number.number = number

        type_ = input('Is this a mobile(0), home(1), or work(2) phone?')
        if type_ == "0":
            phone_number.type = addressbook_pb2.Person.MOBILE
        elif type_ == "1":
            phone_number.type = addressbook_pb2.Person.HOME
        elif type_ == "2":
            phone_number.type = addressbook_pb2.Person.WORK
        else:
            print("Unknown phone type; leaving as default value.")


if len(sys.argv) != 2:
    print('Usage:', sys.argv[0], "ADDRESS_BOOK_FILE")
    sys.exit(0)

a = addressbook_pb2.AddressBook()
try:
    with open(sys.argv[1], 'rb') as f:
        a.ParseFromString(f.read())
        print(a)
except IOError:
    print(sys.argv[1] + ": not found")

b = addressbook_pb2.AddressBook()
person = b.people.add()
PromptForAddress(person)

with open(sys.argv[1], "ab") as f:
    f.write(b.SerializeToString())

试运行一下：

>> python add_person.py my_address_book.txt
my_address_book.txt: not found
Enter ID:1
Enter name:Tom
Enter email:tom@abc.com
Enter phone number (or leave blank to finish):58881234
Is this a mobile(0), home(1), or work(2) phone?2
Enter phone number (or leave blank to finish):

这样会把一条记录保存进二进制文件my_address_book.txt，注意，只能是二进制读写，无法直接打开。
再运行，看看读取的效果：

>> python add_person.py my_address_book.txt
people {
  name: "Tom"
  id: 1
  email: "tom@abc.com"
  phones {
    number: "58881234"
    type: WORK
  }
}

Enter ID:

搞定。