[Intro] Use gRPC in Golang

README.md

[Intro] Use gRPC in Golang

一个处理用户信息的 RPC 实例。客户端通过给定用户名，从服务端查询用户信息。

项目结构如下：

grpc
├── client
│   └── main.go
├── go.mod
├── go.sum
├── proto
│   ├── user.pb.go
│   ├── user.proto
│   └── user_grpc.pb.go
└── server
    └── main.go

grpc_client_main.go

package main

import (
	"context"
	"fmt"
	"google.golang.org/grpc"
	"grpc.learn/proto"
)

func main() {
	// 连接服务
	address := "localhost:8080"
	cc, err := grpc.Dial(address, grpc.WithInsecure())
	if err != nil {
		fmt.Println("Dial error:", err)
	}
	defer cc.Close()

	// 实例化 gRPC 客户端
	client := proto.NewUserInfoClient(cc)

	// 调用服务
	req := &proto.UserRequest{Name: "foo"}
	resp, err := client.GetUserInfo(context.Background(), req)
	if err != nil {
		fmt.Println("GetUserInfo error:", err)
	}
	fmt.Printf("resp: %#v", resp)
}

grpc_go.mod

module grpc.learn

go 1.12

require (
	github.com/golang/protobuf v1.4.0
	golang.org/x/lint v0.0.0-20190313153728-d0100b6bd8b3 // indirect
	golang.org/x/tools v0.0.0-20190524140312-2c0ae7006135 // indirect
	google.golang.org/grpc v1.32.0
	google.golang.org/grpc/cmd/protoc-gen-go-grpc v0.0.0-20200917190803-0f7e218c2cf4 // indirect
	google.golang.org/protobuf v1.23.0
	honnef.co/go/tools v0.0.0-20190523083050-ea95bdfd59fc // indirect
)

grpc_proto_user.pb.go

// Code generated by protoc-gen-go. DO NOT EDIT.
// versions:
// 	protoc-gen-go v1.25.0
// 	protoc        v3.13.0
// source: user.proto

package proto

import (
	proto "github.com/golang/protobuf/proto"
	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
	reflect "reflect"
	sync "sync"
)

const (
	// Verify that this generated code is sufficiently up-to-date.
	_ = protoimpl.EnforceVersion(20 - protoimpl.MinVersion)
	// Verify that runtime/protoimpl is sufficiently up-to-date.
	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
)

// This is a compile-time assertion that a sufficiently up-to-date version
// of the legacy proto package is being used.
const _ = proto.ProtoPackageIsVersion4

// 用户信息请求参数
type UserRequest struct {
	state         protoimpl.MessageState
	sizeCache     protoimpl.SizeCache
	unknownFields protoimpl.UnknownFields

	Name string `protobuf:"bytes,1,opt,name=name,proto3" json:"name,omitempty"`
}

func (x *UserRequest) Reset() {
	*x = UserRequest{}
	if protoimpl.UnsafeEnabled {
		mi := &file_user_proto_msgTypes[0]
		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
		ms.StoreMessageInfo(mi)
	}
}

func (x *UserRequest) String() string {
	return protoimpl.X.MessageStringOf(x)
}

func (*UserRequest) ProtoMessage() {}

func (x *UserRequest) ProtoReflect() protoreflect.Message {
	mi := &file_user_proto_msgTypes[0]
	if protoimpl.UnsafeEnabled && x != nil {
		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
		if ms.LoadMessageInfo() == nil {
			ms.StoreMessageInfo(mi)
		}
		return ms
	}
	return mi.MessageOf(x)
}

// Deprecated: Use UserRequest.ProtoReflect.Descriptor instead.
func (*UserRequest) Descriptor() ([]byte, []int) {
	return file_user_proto_rawDescGZIP(), []int{0}
}

func (x *UserRequest) GetName() string {
	if x != nil {
		return x.Name
	}
	return ""
}

// 用户信息请求响应
type UserResponse struct {
	state         protoimpl.MessageState
	sizeCache     protoimpl.SizeCache
	unknownFields protoimpl.UnknownFields

	Id    int32    `protobuf:"varint,1,opt,name=id,proto3" json:"id,omitempty"`
	Name  string   `protobuf:"bytes,2,opt,name=name,proto3" json:"name,omitempty"`
	Age   int32    `protobuf:"varint,3,opt,name=age,proto3" json:"age,omitempty"`
	Hobby []string `protobuf:"bytes,4,rep,name=hobby,proto3" json:"hobby,omitempty"`
}

func (x *UserResponse) Reset() {
	*x = UserResponse{}
	if protoimpl.UnsafeEnabled {
		mi := &file_user_proto_msgTypes[1]
		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
		ms.StoreMessageInfo(mi)
	}
}

func (x *UserResponse) String() string {
	return protoimpl.X.MessageStringOf(x)
}

func (*UserResponse) ProtoMessage() {}

func (x *UserResponse) ProtoReflect() protoreflect.Message {
	mi := &file_user_proto_msgTypes[1]
	if protoimpl.UnsafeEnabled && x != nil {
		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
		if ms.LoadMessageInfo() == nil {
			ms.StoreMessageInfo(mi)
		}
		return ms
	}
	return mi.MessageOf(x)
}

// Deprecated: Use UserResponse.ProtoReflect.Descriptor instead.
func (*UserResponse) Descriptor() ([]byte, []int) {
	return file_user_proto_rawDescGZIP(), []int{1}
}

func (x *UserResponse) GetId() int32 {
	if x != nil {
		return x.Id
	}
	return 0
}

func (x *UserResponse) GetName() string {
	if x != nil {
		return x.Name
	}
	return ""
}

func (x *UserResponse) GetAge() int32 {
	if x != nil {
		return x.Age
	}
	return 0
}

func (x *UserResponse) GetHobby() []string {
	if x != nil {
		return x.Hobby
	}
	return nil
}

var File_user_proto protoreflect.FileDescriptor

var file_user_proto_rawDesc = []byte{
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}

var (
	file_user_proto_rawDescOnce sync.Once
	file_user_proto_rawDescData = file_user_proto_rawDesc
)

func file_user_proto_rawDescGZIP() []byte {
	file_user_proto_rawDescOnce.Do(func() {
		file_user_proto_rawDescData = protoimpl.X.CompressGZIP(file_user_proto_rawDescData)
	})
	return file_user_proto_rawDescData
}

var file_user_proto_msgTypes = make([]protoimpl.MessageInfo, 2)
var file_user_proto_goTypes = []interface{}{
	(*UserRequest)(nil),  // 0: proto.UserRequest
	(*UserResponse)(nil), // 1: proto.UserResponse
}
var file_user_proto_depIdxs = []int32{
	0, // 0: proto.UserInfo.GetUserInfo:input_type -> proto.UserRequest
	1, // 1: proto.UserInfo.GetUserInfo:output_type -> proto.UserResponse
	1, // [1:2] is the sub-list for method output_type
	0, // [0:1] is the sub-list for method input_type
	0, // [0:0] is the sub-list for extension type_name
	0, // [0:0] is the sub-list for extension extendee
	0, // [0:0] is the sub-list for field type_name
}

func init() { file_user_proto_init() }
func file_user_proto_init() {
	if File_user_proto != nil {
		return
	}
	if !protoimpl.UnsafeEnabled {
		file_user_proto_msgTypes[0].Exporter = func(v interface{}, i int) interface{} {
			switch v := v.(*UserRequest); i {
			case 0:
				return &v.state
			case 1:
				return &v.sizeCache
			case 2:
				return &v.unknownFields
			default:
				return nil
			}
		}
		file_user_proto_msgTypes[1].Exporter = func(v interface{}, i int) interface{} {
			switch v := v.(*UserResponse); i {
			case 0:
				return &v.state
			case 1:
				return &v.sizeCache
			case 2:
				return &v.unknownFields
			default:
				return nil
			}
		}
	}
	type x struct{}
	out := protoimpl.TypeBuilder{
		File: protoimpl.DescBuilder{
			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
			RawDescriptor: file_user_proto_rawDesc,
			NumEnums:      0,
			NumMessages:   2,
			NumExtensions: 0,
			NumServices:   1,
		},
		GoTypes:           file_user_proto_goTypes,
		DependencyIndexes: file_user_proto_depIdxs,
		MessageInfos:      file_user_proto_msgTypes,
	}.Build()
	File_user_proto = out.File
	file_user_proto_rawDesc = nil
	file_user_proto_goTypes = nil
	file_user_proto_depIdxs = nil
}

grpc_proto_user.proto

syntax = "proto3";

package proto;

// 用户信息请求参数
message UserRequest {
  string name = 1;
}

// 用户信息请求响应
message UserResponse {
  int32 id = 1;
  string name = 2;
  int32 age = 3;
  repeated string hobby = 4;
}

// 用户信息接口
service UserInfo {
  // 获取用户信息，请求参数为 UserRequest，返回响应为 UserResponse
  rpc GetUserInfo (UserRequest) returns (UserResponse) {}
}

grpc_proto_user_grpc.pb.go

// Code generated by protoc-gen-go-grpc. DO NOT EDIT.

package proto

import (
	context "context"
	grpc "google.golang.org/grpc"
	codes "google.golang.org/grpc/codes"
	status "google.golang.org/grpc/status"
)

// This is a compile-time assertion to ensure that this generated file
// is compatible with the grpc package it is being compiled against.
const _ = grpc.SupportPackageIsVersion7

// UserInfoClient is the client API for UserInfo service.
//
// For semantics around ctx use and closing/ending streaming RPCs, please refer to https://pkg.go.dev/google.golang.org/grpc/?tab=doc#ClientConn.NewStream.
type UserInfoClient interface {
	// 获取用户信息，请求参数为 UserRequest，返回响应为 UserResponse
	GetUserInfo(ctx context.Context, in *UserRequest, opts ...grpc.CallOption) (*UserResponse, error)
}

type userInfoClient struct {
	cc grpc.ClientConnInterface
}

func NewUserInfoClient(cc grpc.ClientConnInterface) UserInfoClient {
	return &userInfoClient{cc}
}

var userInfoGetUserInfoStreamDesc = &grpc.StreamDesc{
	StreamName: "GetUserInfo",
}

func (c *userInfoClient) GetUserInfo(ctx context.Context, in *UserRequest, opts ...grpc.CallOption) (*UserResponse, error) {
	out := new(UserResponse)
	err := c.cc.Invoke(ctx, "/proto.UserInfo/GetUserInfo", in, out, opts...)
	if err != nil {
		return nil, err
	}
	return out, nil
}

// UserInfoService is the service API for UserInfo service.
// Fields should be assigned to their respective handler implementations only before
// RegisterUserInfoService is called.  Any unassigned fields will result in the
// handler for that method returning an Unimplemented error.
type UserInfoService struct {
	// 获取用户信息，请求参数为 UserRequest，返回响应为 UserResponse
	GetUserInfo func(context.Context, *UserRequest) (*UserResponse, error)
}

func (s *UserInfoService) getUserInfo(_ interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
	in := new(UserRequest)
	if err := dec(in); err != nil {
		return nil, err
	}
	if interceptor == nil {
		return s.GetUserInfo(ctx, in)
	}
	info := &grpc.UnaryServerInfo{
		Server:     s,
		FullMethod: "/proto.UserInfo/GetUserInfo",
	}
	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
		return s.GetUserInfo(ctx, req.(*UserRequest))
	}
	return interceptor(ctx, in, info, handler)
}

// RegisterUserInfoService registers a service implementation with a gRPC server.
func RegisterUserInfoService(s grpc.ServiceRegistrar, srv *UserInfoService) {
	srvCopy := *srv
	if srvCopy.GetUserInfo == nil {
		srvCopy.GetUserInfo = func(context.Context, *UserRequest) (*UserResponse, error) {
			return nil, status.Errorf(codes.Unimplemented, "method GetUserInfo not implemented")
		}
	}
	sd := grpc.ServiceDesc{
		ServiceName: "proto.UserInfo",
		Methods: []grpc.MethodDesc{
			{
				MethodName: "GetUserInfo",
				Handler:    srvCopy.getUserInfo,
			},
		},
		Streams:  []grpc.StreamDesc{},
		Metadata: "user.proto",
	}

	s.RegisterService(&sd, nil)
}

grpc_server_main.go

package main

import (
	"context"
	"fmt"
	"google.golang.org/grpc"
	"grpc.learn/proto"
	"net"
)

// userInfoService 是 proto.UserInfoService 的实例，即 protobuf 中定义的 service UserInfoService 实例
// 需要实现 GetUserInfo 方法
var userInfoService = proto.UserInfoService{
	GetUserInfo: getUserInfo,
}

// getUserInfo 是获取用户信息的具体处理
// 请求参数为 UserRequest，返回响应为 UserResponse
func getUserInfo(ctx context.Context, request *proto.UserRequest) (response *proto.UserResponse, err error) {

	name := request.Name

	fmt.Println("GetUserInfo: name =", name)

	// Fake query
	if name == "foo" {
		response = &proto.UserResponse{
			Id:    1,
			Name:  "foo",
			Age:   12,
			Hobby: []string{"eating", "sleep"},
		}
		return response, nil
	}

	return response, fmt.Errorf("unknown user: name=%s", name)
}

func main() {
	// 实例化 gRPC，注册服务
	s := grpc.NewServer()
	proto.RegisterUserInfoService(s, &userInfoService)

	// 监听网络
	address := "localhost:8080"
	listener, err := net.Listen("tcp", address)
	if err != nil {
		panic(err)
	}
	fmt.Println("Listening tcp:", address)

	// 启动 gRPC 服务
	err = s.Serve(listener)
	if err != nil {
		panic(err)
	}
}