Golang-RPC（六）：gRPC框架初级使用

官网 https://www.grpc.io/ 中文文档 https://doc.oschina.net/grpc?t=58008 代码 https://github.com/grpc/grpc-go

首先安装 protoc和 protoc-gen-go ，参考

1、创建目录结构

grpc-demo
	client
		main.go
	server
		main.go
	pkg
		pbs
			helloworld.proto

cd grpc-demo
go mod init grpc-demo

2、编写helloworld.proto

syntax = "proto3";

option go_package = "pkg/pbs;pbs";

package helloworld;

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

// The request message containing the users name.
message HelloRequest {
  string name = 1;
}

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

注意，这里的 package helloworld;，最终生成的服务名是helloworld.Greeter，完整的方法名 /helloworld.Greeter/SayHello

3、生成接口文件，保存到 pbs 目录下

protoc --go_out=plugins=grpc:./ ./pkg/pbs/helloworld.proto

这个文件几乎不用改动。

编写服务实现，注册服务，启动服务 server/main.go

package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"net"

	"google.golang.org/grpc"
	pb "grpc-demo/pkg/pbs"
)

var (
	port = flag.Int("port", 50051, "The server port")
)

// 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() {
          
   
	flag.Parse()
	lis, err := net.Listen("tcp", fmt.Sprintf(":%d", *port))
	if err != nil {
          
   
		log.Fatalf("failed to listen: %v", err)
	}
	s := grpc.NewServer()
	pb.RegisterGreeterServer(s, &server{
          
   })
	log.Printf("server listening at %v", lis.Addr())
	if err := s.Serve(lis); err != nil {
          
   
		log.Fatalf("failed to serve: %v", err)
	}
}

4、编写客户端，发起RPC调用 client/main.g

package main

import (
	"context"
	"flag"
	"log"
	"time"

	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
	pb "grpc-demo/pkg/pbs"
)

const (
	defaultName = "world"
)

var (
	addr = flag.String("addr", "localhost:50051", "the address to connect to")
	name = flag.String("name", defaultName, "Name to greet")
)

func main() {
          
   
	flag.Parse()
	// Set up a connection to the server.
	conn, err := grpc.Dial(*addr, grpc.WithTransportCredentials(insecure.NewCredentials()))
	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.
	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())
}

5、一切就绪之后开始运行

cd server && go run main.go
2022/06/02 11:13:42 server listening at [::]:50051

cd client && go run main.go
2022/06/02 11:14:38 Greeting: Hello world

服务端打印

2022/06/02 11:14:38 Received: world

至此，一个简单的基于gRPC的通讯就完成。

然后，客户端不限语言，只要是按照 helloworld.proto定义来生成，看起来很不错。