1. 项目结构
   

2. pom引入(parent中引入即可)

   <properties>
       <net-devh-grpc.version>2.14.0.RELEASE</net-devh-grpc.version>
       <os-maven-plugin.version>1.6.0</os-maven-plugin.version>
       <protobuf-maven-plugin.version>0.5.1</protobuf-maven-plugin.version>
   </properties>
   
   <dependency>
       <groupId>net.devh</groupId>
       <artifactId>grpc-spring-boot-starter</artifactId>
       <version>2.14.0.RELEASE</version>
   </dependency>
   

3. 创建lib、service、client服务
   a. lib中, 创建proto文件
   

   syntax = "proto3";
   option java_package = "com.mose.proto.msg";
   
   // 定义service -- 即 class
   service MsgService {
     // 定义 方法名   入参对象     返回      回参对象
     rpc SendMsg (MsgRequest) returns (MsgResponse);
   }
   
   // 定义 入参对象
   // 其中的 1、2、3 只是为了排序
   message MsgRequest {
     int32 a = 1;
     int32 b = 2;
     Type type = 3;
   }
   
   // 定义 回参对象
   message MsgResponse {
     int32 c = 1;
   }
   
   // 定义 入参/回参 枚举类型
   // 默认值为第一个,即 = 0 的为默认值
   enum Type {
     add = 0;
     cut = 1;
   }
   

b. pom中增加build信息

 <build>
     <extensions>
         <!-- os-maven-plugin -->
         <extension>
             <groupId>kr.motd.maven</groupId>
             <artifactId>os-maven-plugin</artifactId>
             <version>${os-maven-plugin.version}</version>
         </extension>
     </extensions>
     <plugins>
         <plugin>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-maven-plugin</artifactId>
             <executions>
                 <execution>
                     <goals>
                         <goal>repackage</goal>
                     </goals>
                 </execution>
             </executions>
         </plugin>
         <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-surefire-plugin</artifactId>
             <configuration>
                 <skip>true</skip>
             </configuration>
         </plugin>
         <!-- protobuf-maven-plugin -->
         <plugin>
             <groupId>org.xolstice.maven.plugins</groupId>
             <artifactId>protobuf-maven-plugin</artifactId>
             <version>${protobuf-maven-plugin.version}</version>
             <configuration>
                 <protocArtifact>com.google.protobuf:protoc:3.5.1-1:exe:${os.detected.classifier}</protocArtifact>
                 <pluginId>grpc-java</pluginId>
                 <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.11.0:exe:${os.detected.classifier}</pluginArtifact>
                 <outputDirectory>${project.build.sourceDirectory}</outputDirectory>
                 <clearOutputDirectory>false</clearOutputDirectory>
             </configuration>
             <executions>
                 <execution>
                     <goals>
                         <goal>compile</goal>
                         <goal>compile-custom</goal>
                     </goals>
                 </execution>
             </executions>
         </plugin>
     </plugins>
 </build>

c. 在lib中执行 mvn clean install , 即可生成proto文件对应的java文件,如下图

3. service 实现接口

   server:
     port: 8081
   spring:
     application:
       name: grpc-service
   grpc:
     server:
       port: 9091
   

   import com.mose.proto.msg.Msg;
   import com.mose.proto.msg.MsgServiceGrpc;
   import io.grpc.stub.StreamObserver;
   import net.devh.boot.grpc.server.service.GrpcService;
   
   @GrpcService
   public class MsgService extends MsgServiceGrpc.MsgServiceImplBase {
       @Override
       public void sendMsg(Msg.MsgRequest request, StreamObserver<Msg.MsgResponse> responseObserver) {
           // 获取参数
           int a = request.getA();
           int b = request.getB();
           Msg.Type type = request.getType();
   
           // 处理逻辑
           int c = 0;
   
           switch (type) {
               case add:
                   c = a + b;
                   break;
               case cut:
                   c = a - b;
                   break;
           }
   
           // 构造回参
           Msg.MsgResponse response = Msg.MsgResponse.newBuilder().setC(c).build();
   
           // 返回
           responseObserver.onNext(response);
   
           // 处理完成
           responseObserver.onCompleted();
       }
   }
   

4. client 调用接口

   server:
     port: 8082
   spring:
     application:
       name: grpc-client
   grpc:
     server:
       port: 9092
     client:
       grpc-service:
         address: localhost:9091
         negotiation-type: plaintext
   

   import com.mose.proto.msg.Msg;
   import com.mose.proto.msg.MsgServiceGrpc;
   import net.devh.boot.grpc.client.inject.GrpcClient;
   import org.springframework.web.bind.annotation.GetMapping;
   import org.springframework.web.bind.annotation.RestController;
   
   @RestController
   public class MsgController {
   
       /**
        * 获取调用存根
        */
       @GrpcClient("grpc-service")
       private MsgServiceGrpc.MsgServiceBlockingStub stub;
   
       @GetMapping("msg")
       public int sendMsg(int a, int b) {
           return stub.sendMsg(
                           // 构造入参
                           Msg.MsgRequest.newBuilder().setA(a).setB(b).setType(Msg.Type.cut).build()
                   )
                   // 获取回参
                   .getC();
       }
   }
   
   

5. 调用 以及结果