Java实现gRPC服务

GRPC

gRPC由GOOGLE开发，是一款语言中立、平台中立、开源的远程过程调用(RPC)系统。

PB协议

syntax = "proto3";

package com.example.grpc;

option java_multiple_files = true;

enum Sentiment {
    HAPPY = 0;
    SLEEPY = 1;
    ANGRY = 2;
}

message HelloRequest {
    string name = 1;
    int32 age = 2;
    repeated string hobbies = 3;
    map<string, string> bagOfTricks = 4;
    Sentiment sentiment = 5;
}

message HelloResponse {
    string greeting = 1;
}

// 4. service, unary request/response
service GreetingService {
    rpc greeting(HelloRequest) returns (HelloResponse);
}

Maven

pb和gRPC包

    <dependency>
        <groupId>com.google.protobuf</groupId>
        <artifactId>protobuf-java</artifactId>
        <version>3.10.0</version>
    </dependency>

    <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-netty-shaded</artifactId>
        <version>1.31.0</version>
    </dependency>
    <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-protobuf</artifactId>
        <version>1.31.0</version>
    </dependency>
    <dependency>
        <groupId>io.grpc</groupId>
        <artifactId>grpc-stub</artifactId>
        <version>1.31.0</version>
    </dependency>
</dependencies>

编译

<build>
    <defaultGoal>package</defaultGoal>
    <extensions>
        <extension>
            <groupId>kr.motd.maven</groupId>
            <artifactId>os-maven-plugin</artifactId>
            <version>1.6.2</version>
        </extension>
    </extensions>

    <plugins>
        <!-- protobuf 编译组件 -->
        <plugin>
            <groupId>org.xolstice.maven.plugins</groupId>
            <artifactId>protobuf-maven-plugin</artifactId>
            <version>0.5.1</version>
            <extensions>true</extensions>
            <configuration>
                <outputDirectory>${project.build.directory}/generated-sources/protobuf/java</outputDirectory>
                <protoSourceRoot>${project.basedir}/src/main/proto</protoSourceRoot>
                <protocArtifact>com.google.protobuf:protoc:3.5.1:exe:${os.detected.classifier}</protocArtifact>
                <pluginId>grpc-java</pluginId>
                <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.20.0:exe:${os.detected.classifier}</pluginArtifact>
            </configuration>
            <executions>
                <execution>
                    <goals>
                        <goal>compile</goal>
                        <goal>compile-custom</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

Server

public class MyGrpcServer {
  static public void main(String [] args) throws IOException, InterruptedException {
    Server server = ServerBuilder.forPort(8080)
        .addService(new GreetingServiceImpl()).build();

    System.out.println("Starting server...");
    server.start();
    System.out.println("Server started!");
    server.awaitTermination();
  }

  public static class GreetingServiceImpl extends GreetingServiceGrpc.GreetingServiceImplBase {
    @Override
    public void greeting(HelloRequest request, StreamObserver<HelloResponse> responseObserver) {
      System.out.println(request);

      String greeting = "Hello there, " + request.getName();

      HelloResponse response = HelloResponse.newBuilder().setGreeting(greeting).build();

      responseObserver.onNext(response);
      responseObserver.onCompleted();
    }
  }
}

Client

public class MyGrpcClient {
  public static void main(String[] args) throws InterruptedException {
    ManagedChannel channel = ManagedChannelBuilder.forAddress("localhost", 8080)
        .usePlaintext(true)
        .build();

    GreetingServiceGrpc.GreetingServiceBlockingStub stub =
        GreetingServiceGrpc.newBlockingStub(channel);

    HelloResponse helloResponse = stub.greeting(
        HelloRequest.newBuilder()
            .setName("Ray")
            .setAge(18)
            .setSentiment(Sentiment.HAPPY)
            .build());

    System.out.println(helloResponse);

    channel.shutdown();
  }
}