gRPC go 入门示例

准备

操作环境：macOS Big Sur

• 安装 protobuf

brew install protobuf

• 安装 protoc-gen-go*

go get google.golang.org/protobuf/cmd/protoc-gen-go
go get google.golang.org/grpc/cmd/protoc-gen-go-grpc

编写 proto

syntax = "proto3";

option go_package = "github.com/feivxs/helloworld";
option java_multiple_files = true;
option java_package = "io.grpc.examples.helloworld";
option java_outer_classname = "HelloWorldProto";

package helloworld;

// The greeting service definition.
service Greeter {
  // Sends a greeting
  rpc SayHello (HelloRequest) returns (HelloReply) {}
}

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

// The response message containing the greetings
message HelloReply {
  string message = 1;
}

生成 client & server 端接口

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

当上述命令成功执行后，会生成两个文件，分别为：

$ tree helloworld 
helloworld
├── helloworld.proto
├── helloworld.pb.go (generated)
└── helloworld_grpc.pb.go (generated)

其中所生成的两个文件的作用分别为：

• helloworld.pb.go生成 proto buffer 相关代码，包括请求、响应类型，以及发布、序列化等。
• helloworld_grpc.pb.go
• 一个给 client 调用的接口类型（定义在 proto 中的方法）
• 一个给 server 端实现的接口类型（定义在 proto 中的方法）

编写 server 端实现接口代码

package main

import (
	"context"
	"log"
	"net"

	pb "github.com/feivxs/helloworld/helloworld"
	"google.golang.org/grpc"
)

const (
	port = ":50051"
)

// server is used to implement helloworld.GreeterServer.
type server struct {
	pb.UnimplementedGreeterServer
}

// SayHello implements helloworld.GreeterServer
func (s *server) SayHello(ctx context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
	log.Printf("Received: %v", in.GetName())
	return &pb.HelloReply{Message: "Hello " + in.GetName()}, nil
}

func main() {
	lis, err := net.Listen("tcp", port)
	if err != nil {
		log.Fatalf("failed to listen: %v", err)
	}
	s := grpc.NewServer()
	pb.RegisterGreeterServer(s, &server{})
	if err := s.Serve(lis); err != nil {
		log.Fatalf("failed to serve: %v", err)
	}
}

编写 client 端调用接口代码

package main

import (
	"context"
	"log"
	"os"
	"time"

	pb "github.com/feivxs/helloworld/helloworld"

	"google.golang.org/grpc"
)

const (
	address     = "localhost:50051"
	defaultName = "world"
)

func main() {
	// Set up a connection to the server.
	conn, err := grpc.Dial(address, grpc.WithInsecure(), grpc.WithBlock())
	if err != nil {
		log.Fatalf("did not connect: %v", err)
	}
	defer conn.Close()
	c := pb.NewGreeterClient(conn)

	// Contact the server and print out its response.
	name := defaultName
	if len(os.Args) > 1 {
		name = os.Args[1]
	}
	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	r, err := c.SayHello(ctx, &pb.HelloRequest{Name: name})
	if err != nil {
		log.Fatalf("could not greet: %v", err)
	}
	log.Printf("Greeting: %s", r.GetMessage())
}

Reference

• https://grpc.io/docs/languages/go/basics
• https://grpc.io/docs/languages/go/quickstart