Protocol Buffer 基础知识：Dart

syntax = "proto3";
package tutorial;

import "google/protobuf/timestamp.proto";

message Person {
  string name = 1;
  int32 id = 2;  // Unique ID number for this person.
  string email = 3;

  enum PhoneType {
    PHONE_TYPE_UNSPECIFIED = 0;
    PHONE_TYPE_MOBILE = 1;
    PHONE_TYPE_HOME = 2;
    PHONE_TYPE_WORK = 3;
  }

  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;
}

import 'dart:io';

import 'dart_tutorial/addressbook.pb.dart';

// This function fills in a Person message based on user input.
Person promptForAddress() {
  Person person = Person();

  print('Enter person ID: ');
  String input = stdin.readLineSync();
  person.id = int.parse(input);

  print('Enter name');
  person.name = stdin.readLineSync();

  print('Enter email address (blank for none) : ');
  String email = stdin.readLineSync();
  if (email.isNotEmpty) {
    person.email = email;
  }

  while (true) {
    print('Enter a phone number (or leave blank to finish): ');
    String number = stdin.readLineSync();
    if (number.isEmpty) break;

    Person_PhoneNumber phoneNumber = Person_PhoneNumber();

    phoneNumber.number = number;
    print('Is this a mobile, home, or work phone? ');

    String type = stdin.readLineSync();
    switch (type) {
      case 'mobile':
        phoneNumber.type = Person_PhoneType.PHONE_TYPE_MOBILE;
        break;
      case 'home':
        phoneNumber.type = Person_PhoneType.PHONE_TYPE_HOME;
        break;
      case 'work':
        phoneNumber.type = Person_PhoneType.PHONE_TYPE_WORK;
        break;
      default:
        print('Unknown phone type.  Using default.');
    }
    person.phones.add(phoneNumber);
  }

  return person;
}

// Reads the entire address book from a file, adds one person based
// on user input, then writes it back out to the same file.
main(List arguments) {
  if (arguments.length != 1) {
    print('Usage: add_person ADDRESS_BOOK_FILE');
    exit(-1);
  }

  File file = File(arguments.first);
  AddressBook addressBook;
  if (!file.existsSync()) {
    print('File not found. Creating new file.');
    addressBook = AddressBook();
  } else {
    addressBook = AddressBook.fromBuffer(file.readAsBytesSync());
  }
  addressBook.people.add(promptForAddress());
  file.writeAsBytes(addressBook.writeToBuffer());
}

import 'dart:io';

import 'dart_tutorial/addressbook.pb.dart';
import 'dart_tutorial/addressbook.pbenum.dart';

// Iterates though all people in the AddressBook and prints info about them.
void printAddressBook(AddressBook addressBook) {
  for (Person person in addressBook.people) {
    print('Person ID: ${ person.id}');
    print('  Name: ${ person.name}');
    if (person.hasEmail()) {
      print('  E-mail address:${ person.email}');
    }

    for (Person_PhoneNumber phoneNumber in person.phones) {
      switch (phoneNumber.type) {
        case Person_PhoneType.PHONE_TYPE_MOBILE:
          print('   Mobile phone #: ');
          break;
        case Person_PhoneType.PHONE_TYPE_HOME:
          print('   Home phone #: ');
          break;
        case Person_PhoneType.PHONE_TYPE_WORK:
          print('   Work phone #: ');
          break;
        default:
          print('   Unknown phone #: ');
          break;
      }
      print(phoneNumber.number);
    }
  }
}

// Reads the entire address book from a file and prints all
// the information inside.
main(List arguments) {
  if (arguments.length != 1) {
    print('Usage: list_person ADDRESS_BOOK_FILE');
    exit(-1);
  }

  // Read the existing address book.
  File file = new File(arguments.first);
 AddressBook addressBook = new AddressBook.fromBuffer(file.readAsBytesSync());
  printAddressBook(addressBook);
}