Protocol Buffers (Protobuf) 详解

syntax = "proto3";

message Person {
  string name = 1;
  int32 id = 2;
  string email = 3;
  
  enum PhoneType {
    MOBILE = 0;
    HOME = 1;
    WORK = 2;
  }
  
  message PhoneNumber {
    string number = 1;
    PhoneType type = 2;
  }
  
  repeated PhoneNumber phones = 4;
}

// proto2
syntax = "proto2";
message Example {
  required string name = 1;    // 必须字段
  optional int32 id = 2;       // 可选字段
  repeated string emails = 3;  // 重复字段
}

// proto3
syntax = "proto3";
message Example {
  string name = 1;            // 默认都是可选
  int32 id = 2;
  repeated string emails = 3;
}

message SampleMessage {
  oneof test_oneof {
    string name = 1;
    int32 id = 2;
  }
}

message Product {
  map<string, string> properties = 1;
}

message Outer {
  message Inner {
    string text = 1;
  }
  Inner inner = 1;
}

import "other.proto";

package my.package;

// Java 特定选项
option java_package = "com.example.generated";
option java_outer_classname = "ExampleProto";

syntax = "proto3";

package tutorial;

option java_package = "com.example.tutorial";
option java_outer_classname = "AddressBookProtos";

message Person {
  string name = 1;
  int32 id = 2;
  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;
}

import addressbook_pb2

# 创建消息
person = addressbook_pb2.Person()
person.id = 1234
person.name = "John Doe"
person.email = "jdoe@example.com"

phone = person.phones.add()
phone.number = "555-4321"
phone.type = addressbook_pb2.Person.HOME

# 序列化
serialized_data = person.SerializeToString()

# 反序列化
new_person = addressbook_pb2.Person()
new_person.ParseFromString(serialized_data)

print(f"Name: {new_person.name}")
print(f"Email: {new_person.email}")

// 创建 Builder
Person person = Person.newBuilder()
    .setId(1234)
    .setName("John Doe")
    .setEmail("jdoe@example.com")
    .addPhones(
        Person.PhoneNumber.newBuilder()
            .setNumber("555-4321")
            .setType(Person.PhoneType.HOME)
            .build())
    .build();

// 序列化
byte[] serializedData = person.toByteArray();

// 反序列化
Person newPerson = Person.parseFrom(serializedData);

System.out.println("Name: " + newPerson.getName());
System.out.println("Email: " + newPerson.getEmail());

# 下载 protoc 编译器
# 或使用包管理器安装

# 生成 Java 代码
protoc --java_out=. addressbook.proto

# 生成 Python 代码
protoc --python_out=. addressbook.proto

# 生成多种语言
protoc --java_out=. --python_out=. --cpp_out=. addressbook.proto

message Foo {
  reserved 2, 15, 9 to 11;
  reserved "foo", "bar";
}