1、定义一个服务-useinfoservice.proto

syntax = "proto3";//标识 proto版本 建议使用proto3
package userinfoservice;//proto包名 避免命名冲突，也可以作为引入其他proto文件时使用
option java_package = "com.example.userinfoservice" ;//生成的类将带有此包名，不指定则使用package
option cc_generic_services = true;
option go_package = "./pb";
option java_outer_classname = "UserInfoEntity";//指定生成后的类名，里面会包含req/res,不指定则使用文件名

message GetUserInfoReq{
  string id = 1;
}
message GetUserInfoRes{
  string id = 1;
  string name = 2;
  int32 age = 3;
}

service UserInfoService {
  rpc getUserInfo(GetUserInfoReq) returns (GetUserInfoRes);
}

2、通过proto文件生成代码

1) Go

• 安装protoc命令

$ go install google.golang.org/protobuf/cmd/[email protected]
$ go install google.golang.org/grpc/cmd/[email protected]
$ export PATH="$PATH:$(go env GOPATH)/bin"

• 生成userinfo.pb.go文件和userinfo_grpc.pb.go

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

2) Java

• 将你的proto文件放到src/main/proto和src/test/proto目录，并配置生成代码的插件

• Gradle生成代码插件：

  /*
   * This file was generated by the Gradle 'init' task.
   *
   * This generated file contains a sample Java application project to get you started.
   * For more details take a look at the 'Building Java & JVM projects' chapter in the Gradle
   * User Manual available at <https://docs.gradle.org/7.2/userguide/building_java_projects.html>
   */
  plugins {
      // Apply the application plugin to add support for building a CLI application in Java.
      id 'application'
      // ASSUMES GRADLE 5.6 OR HIGHER. Use plugin version 0.8.10 with earlier gradle versions
      id 'com.google.protobuf' version '0.8.17'
      // Generate IntelliJ IDEA's .idea & .iml project files
      id 'idea'
      id 'java'
  }
  
  sourceCompatibility = 1.8
  targetCompatibility = 1.8
  
  repositories {
      // Use Maven Central for resolving dependencies.
      mavenCentral()
      repositories {
          maven { url '<https://maven.aliyun.com/repository/google/>' }
          maven { url '<https://maven.aliyun.com/repository/jcenter/>'}
      }
  }
  def grpcVersion = '1.48.0' // CURRENT_GRPC_VERSION
  dependencies {
      // Use JUnit test framework.
      testImplementation 'junit:junit:4.13.2'
  
      // This dependency is used by the application.
      implementation 'com.google.guava:guava:30.1.1-jre'
      implementation "io.grpc:grpc-netty:${grpcVersion}"
      implementation "io.grpc:grpc-protobuf:${grpcVersion}"
      implementation "io.grpc:grpc-services:${grpcVersion}"
      implementation "io.grpc:grpc-stub:${grpcVersion}"
  }
  
  application {
      // Define the main class for the application.
      mainClass = 'client.MainApplication'
  }
  protobuf {
      protoc {
          artifact = "com.google.protobuf:protoc:3.2.0"
      }
      plugins {
          grpc {
              artifact = 'io.grpc:protoc-gen-grpc-java:1.4.0'
          }
      }
      generateProtoTasks {
          all()*.plugins {
              grpc {}
          }
      }
  }
  

• Maven生成代码插件：

  <build>
    <extensions>
      <extension>
        <groupId>kr.motd.maven</groupId>
        <artifactId>os-maven-plugin</artifactId>
        <version>1.4.1.Final</version>
      </extension>
    </extensions>
    <plugins>
      <plugin>
        <groupId>org.xolstice.maven.plugins</groupId>
        <artifactId>protobuf-maven-plugin</artifactId>
        <version>0.5.0</version>
        <configuration>
          <protocArtifact>com.google.protobuf:protoc:3.3.0:exe:${os.detected.classifier}</protocArtifact>
          <pluginId>grpc-java</pluginId>
          <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.4.0:exe:${os.detected.classifier}</pluginArtifact>
        </configuration>
        <executions>
          <execution>
            <goals>
              <goal>compile</goal>
              <goal>compile-custom</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  

  3、对应生成服务端和客户端

  （1 ）Java 服务端

  package com.example.userinfoservice.impl;
  
  import com.example.userinfoservice.UserInfoEntity;
  import com.example.userinfoservice.UserInfoServiceGrpc;
  import com.example.userinfoservice.entity.UserInfoData;
  import com.google.common.collect.Maps;
  import io.grpc.stub.StreamObserver;
  import org.apache.commons.lang3.StringUtils;
  
  import java.util.HashMap;
  
  public class UserInfoServiceImpl extends UserInfoServiceGrpc.UserInfoServiceImplBase {
  
      private HashMap<String, UserInfoData> userinfoHashMap = Maps.newHashMap();
  
      @Override
      public void getUserInfo(UserInfoEntity.GetUserInfoReq request, StreamObserver<UserInfoEntity.GetUserInfoRes> responseObserver) {
  
          System.out.println("java服务收到请求");
          if (StringUtils.isEmpty(request.getId())){
              responseObserver.onError(new Exception("id不能为空"));
              responseObserver.onCompleted();
              return;
          }
  
          if (userinfoHashMap.isEmpty()){
              initUserInfoHashMap();
          }
  
          UserInfoData userInfoData = userinfoHashMap.get(request.getId());
          if (userInfoData == null){
              responseObserver.onError(new Exception("id不能为空"));
              responseObserver.onCompleted();
              return;
          }
          responseObserver.onNext(UserInfoEntity.GetUserInfoRes.newBuilder()
                  .setId(userInfoData.getId())
                  .setName(userInfoData.getName())
                  .setAge(userInfoData.getAge())
                  .build());
          responseObserver.onCompleted();
      }
  
      private void initUserInfoHashMap() {
          userinfoHashMap.put("1",new UserInfoData("1","小美",24));
          userinfoHashMap.put("2",new UserInfoData("2","小强",28));
          userinfoHashMap.put("3",new UserInfoData("3","小刚",30));
      }
  }
  

  • 实体 UserInfoData

  package com.example.userinfoservice.entity;
  
  public class UserInfoData{
      private String id;
      private String name;
      private int age;
  
      public UserInfoData() {
      }
  
      public UserInfoData(String id, String name, int age) {
          this.id = id;
          this.name = name;
          this.age = age;
      }
  
      public String getId() {
          return id;
      }
  
      public void setId(String id) {
          this.id = id;
      }
  
      public String getName() {
          return name;
      }
  
      public void setName(String name) {
          this.name = name;
      }
  
      public int getAge() {
          return age;
      }
  
      public void setAge(int age) {
          this.age = age;
      }
  }
  

  • 服务主类 App

  /*
   * This Java source file was generated by the Gradle 'init' task.
   */
  package com.example.userinfoservice;
  
  import com.example.userinfoservice.impl.UserInfoServiceImpl;
  import io.grpc.Server;
  import io.grpc.ServerBuilder;
  
  import java.io.IOException;
  import java.util.logging.Logger;
  
  public class App {
      public String getGreeting() {
          return "Hello World!";
      }
  
      private static final Logger logger = Logger.getLogger(App.class.getName());
  
      private Server server;
  
      private void start() throws IOException {
          int port = 10080;
          server = ServerBuilder.forPort(port)
                  .addService(new UserInfoServiceImpl())
                  .build()
                  .start();
          logger.info("Server started, listening on " + port);
          Runtime.getRuntime().addShutdownHook(new Thread(() -> {
              // Use stderr here since the logger may have been reset by its JVM shutdown hook.
              logger.info("*** shutting down gRPC server since JVM is shutting down");
              App.this.stop();
              logger.info("*** server shut down");
          }));
      }
  
      private void stop() {
          if (server != null) {
              server.shutdown();
          }
      }
  
      /**
       * Await termination on the main thread since the grpc library uses daemon threads.
       */
      private void blockUntilShutdown() throws InterruptedException {
          if (server != null) {
              server.awaitTermination();
          }
      }
  
      /**
       * Main launches the server from the command line.
       */
      public static void main(String[] args) throws IOException, InterruptedException {
          final App server = new App();
          server.start();
          server.blockUntilShutdown();
      }
  }
  

  （2）Java 客户端

  package com.example.userinfoservice;
  
  import io.grpc.ManagedChannel;
  import io.grpc.ManagedChannelBuilder;
  
  import java.util.logging.Logger;
  
  public class MainApplication {
  
      private static final Logger logger = Logger.getLogger(MainApplication.class.getName());
  
      public static void main(String[] args) throws InterruptedException {
          ManagedChannel channel = ManagedChannelBuilder.forAddress("localhost", 10080)
                  .usePlaintext()
                  .build();
  
          UserInfoServiceGrpc.UserInfoServiceBlockingStub stub =
                  UserInfoServiceGrpc.newBlockingStub(channel);
  
          Userinfo.GetUserInfoRes res = stub.getUserInfo(
                  Userinfo.GetUserInfoReq.newBuilder()
                          .setId("1")
                          .build());
          logger.info("用户id: " + res.getId() + "\\t用户姓名:"+ res.getName()
          +"\\t用户年龄:"+ res.getAge());
          channel.shutdown();
      }
  }
  

  （3）go 服务端

  • 实现用户服务

  package serviceimpl
  
  import (
  	"context"
  	"errors"
  	"grpc-in-action/part1/go/server/pb"
  	"log"
  )
  
  type UserInfo struct {
  	Id string
  	Name string
  	Age int32
  }
  type UserInfoServiceImpl struct {
  	UserInfoData map[string]*UserInfo
  	pb.UnimplementedUserInfoServiceServer
  }
  
  func (server *UserInfoServiceImpl) GetUserInfo(ctx context.Context, in *pb.GetUserInfoReq) (*pb.GetUserInfoRes, error)  {
  
  	log.Printf("go server收到请求")
  	//初始化一个map
  	if server.UserInfoData == nil{
  		server.initUserInfoData()
  	}
  	data:= server.UserInfoData[in.Id]
  	if data == nil{
  		return nil,errors.New("该id不存在")
  	}
  	res := &pb.GetUserInfoRes{
  		Id:   data.Id,
  		Name: data.Name,
  		Age:  data.Age,
  	}
  
  	return res,nil
  }
  
  func (server *UserInfoServiceImpl) initUserInfoData (){
  	server.UserInfoData = make(map[string]*UserInfo)
  
  	server.UserInfoData["1"] = &UserInfo{
  		Id:   "1",
  		Name: "小美",
  		Age:  18,
  	}
  	server.UserInfoData["2"] = &UserInfo{
  		Id:   "2",
  		Name: "小刚",
  		Age:  28,
  	}
  	server.UserInfoData["3"] = &UserInfo{
  		Id:   "3",
  		Name: "小王",
  		Age:  20,
  	}
  }
  

  • 服务主类

  package main
  
  import (
  	"google.golang.org/grpc"
  	"google.golang.org/grpc/reflection"
  	"grpc-in-action/part1/go/server/pb"
  	"grpc-in-action/part1/go/server/serviceimpl"
  	"log"
  	"net"
  )
  
  func main() {
  	lis, err := net.Listen("tcp", "localhost:10080")
  	if err != nil {
  		log.Fatalf("failed to listen: %v", err)
  	}
  	s := grpc.NewServer()
  	ser := &serviceimpl.UserInfoServiceImpl{}
  	pb.RegisterUserInfoServiceServer(s,ser)
  	log.Printf("start")
  	reflection.Register(s)
  	if err := s.Serve(lis); err != nil {
  		log.Fatalf("failed to serve: %v", err)
  	}
  }
  

  （4）go 客户端

  package main
  
  import (
  	"context"
  	"google.golang.org/grpc"
  	"google.golang.org/grpc/credentials/insecure"
  	"grpc-in-action/part1/go/client/pb"
  	"log"
  )
  
  func main() {
  
  	// Set up a connection to the server.
  	conn, err := grpc.Dial("localhost:10080",grpc.WithTransportCredentials(insecure.NewCredentials()))
  	if err != nil {
  		log.Fatalf("did not connect: %v", err)
  	}
  	defer conn.Close()
  	c := pb.NewUserInfoServiceClient(conn)
  	req:= &pb.GetUserInfoReq{Id: "1"}
  	res,err :=c.GetUserInfo(context.Background(),req)
  	if err != nil {
  		log.Fatalf("err:%+v",err)
  	}else {
  		log.Printf("res:%+v",res)
  	}
  
  }