[TOC]

---

## build.gradle 新增GRPC套件

plugins {
    id 'org.springframework.boot'
    id 'io.spring.dependency-management'
    id 'java'
    id 'com.google.protobuf'
}
...
...
dependencies {
    ...
    implementation 'io.github.lognet:grpc-spring-boot-starter'
    ...
}

protobuf {
    protoc { artifact = "com.google.protobuf:protoc:3.23.2" }
    plugins {
        grpc { artifact = "io.grpc:protoc-gen-grpc-java:1.55.1" }
    }
    generateProtoTasks {
        all()*.plugins { grpc {} }
    }
}
 
sourceSets {
    main {
        java {
            srcDirs 'build/generated/source/proto/main/grpc'
            srcDirs 'build/generated/source/proto/main/java'
        }
    }
}

---

## Add proto file

路徑在

src/main/proto

這邊我們新增一個helloworld.proto

syntax = "proto3";

option java_multiple_files = true;
option java_package = "helloworld";

package helloworld;

service GreetingService {
  rpc SayHello (RequestMessage) returns (ResponseMessage) {}
}

message RequestMessage {
  string name = 1;
}

message ResponseMessage {
  string message = 1;
}

接下來將proto build成java檔

./gradlew clean build

---

## Add GRPCService

package web.grpc.controller;

import org.lognet.springboot.grpc.GRpcService;
import org.springframework.beans.factory.annotation.Autowired;

import helloworld.GreetingServiceGrpc;
import helloworld.RequestMessage;
import helloworld.ResponseMessage;
import io.grpc.stub.StreamObserver;
import web.service.TestService;

@GRpcService
public class GreetingController extends GreetingServiceGrpc.GreetingServiceImplBase {

    @Autowired
    private TestService testService;


    @Override
    public void sayHello(RequestMessage req, StreamObserver<ResponseMessage> responseObserver) {
        ResponseMessage reply = ResponseMessage.newBuilder()
                .setMessage("Hello " + req.getName() + ", from server").build();
        responseObserver.onNext(reply);
        responseObserver.onCompleted();

    }

}

---

## Add Test code

@PostMapping("testGrpc.do")
    @ResponseBody
    public ApiResult testGrpc() throws InterruptedException {

        Map<String,Object> returnMap = new HashMap<>();

        final ManagedChannel channel = ManagedChannelBuilder.forAddress("localhost", 6565)
                .usePlaintext()
                .build();

        RequestMessage request = RequestMessage.newBuilder().setName("Himanshu").build();
        ResponseMessage response;
        try {
            response = GreetingServiceGrpc.newBlockingStub(channel).sayHello(request);
            System.out.println(response.getMessage());
        } catch (StatusRuntimeException e) {
            e.printStackTrace();
        } finally {
            channel.shutdownNow().awaitTermination(5, TimeUnit.SECONDS);
        }
        return ApiResult.builder(ApiResult.ReturnCode.SUCC).setData(returnMap);
    }

---