附录A：Proto3 语法速查表

文件结构

syntax = "proto3";
package mypack;
option go_package = "module/path;packname";
import "other.proto";

基本类型

Proto	Go	默认值
int32/64	int32/64	0
uint32/64	uint32/64	0
float/double	float32/64	0.0
bool	bool	false
string	string	""
bytes	[]byte	[]

Message

message User {
  uint64 id = 1;
  string name = 2;
  repeated string tags = 3;      // 数组
  map<string, int32> scores = 4; // 字典
  Address address = 5;           // 嵌套
  Gender gender = 6;             // 枚举
}

Enum

enum Status { UNKNOWN = 0; ACTIVE = 1; INACTIVE = 2; }
// ⚠️ 第一个值必须是 0

Service（四种模式）

service Svc {
  rpc Unary(Req) returns (Resp);                          // 一元
  rpc ServerStream(Req) returns (stream Resp);            // 服务端流
  rpc ClientStream(stream Req) returns (Resp);            // 客户端流
  rpc BidiStream(stream Req) returns (stream Resp);       // 双向流
}

Well-Known Types

import "google/protobuf/timestamp.proto";
import "google/protobuf/duration.proto";
import "google/protobuf/empty.proto";
import "google/protobuf/wrappers.proto";
import "google/protobuf/any.proto";

oneof

message Response {
  oneof result {
    User user = 1;
    Error error = 2;
  }
}

Go 代码生成

protoc --go_out=. --go_opt=paths=source_relative \
       --go-grpc_out=. --go-grpc_opt=paths=source_relative \
       proto/hello.proto