java中使用GRPC，搭建RPCserver

1.pom.xml中加入依赖

  io.grpc
  grpc-netty-shaded
  1.20.0


  io.grpc
  grpc-protobuf
  1.20.0


  io.grpc
  grpc-stub
  1.20.0

2.pom.xml中加入基于protobuf的代码生成插件

  
    
      kr.motd.maven
      os-maven-plugin
      1.5.0.Final
    
  
  
    
      org.xolstice.maven.plugins
      protobuf-maven-plugin
      0.5.1
      
        com.google.protobuf:protoc:3.7.1:exe:${os.detected.classifier}
        grpc-java
        io.grpc:protoc-gen-grpc-java:1.20.0:exe:${os.detected.classifier}
      
      
        
          
            compile
            compile-custom
          
        
      
    
  

3.在src/main/proto文件夹下，新建proto文件，例如holleworld.proto：

// Copyright 2015 The gRPC Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
syntax = "proto3";

option java_multiple_files = true;
option java_package = "io.grpc.examples.helloworld";
option java_outer_classname = "HelloWorldProto";
option objc_class_prefix = "HLW";

package helloworld;

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

// The request message containing the user's name.
message HelloRequest {
  string name = 1;
}

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

4.生成相关代码 mvn package，生成的代码在target/generated-sources下
5.实现HelloWorld接口，新建HelloWorldServer.java，如下：

public class HelloWorldServer {
    private static final Logger logger = Logger.getLogger(HelloWorldServer.class.getName());

    private Server server;

    public void start() throws IOException {
        /* The port on which the server should run */
        int port = 50051;
        server = ServerBuilder.forPort(port)
            .addService(new GreeterImpl())
            .build()
            .start();
        logger.info("Server started, listening on " + port);
        Runtime.getRuntime().addShutdownHook(new Thread() {
            @Override
            public void run() {
                // Use stderr here since the logger may have been reset by its JVM shutdown hook.
                System.err.println("*** shutting down gRPC server since JVM is shutting down");
                HelloWorldServer.this.stop();
                System.err.println("*** server shut down");
            }
        });
    }

    private void stop() {
        if (server != null) {
            server.shutdown();
        }
    }

    /**
     * Await termination on the main thread since the grpc library uses daemon threads.
     */
    public 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 HelloWorldServer server = new HelloWorldServer();
        server.start();
        server.blockUntilShutdown();
    }

    static class GreeterImpl extends GreeterGrpc.GreeterImplBase {

        @Override
        public void sayHello(HelloRequest req, StreamObserver responseObserver) {
            HelloReply reply = HelloReply.newBuilder().setMessage("Hello " + req.getName()).build();
            responseObserver.onNext(reply);
            responseObserver.onCompleted();
        }
    }
}

6.运行HelloWorldServer，开始监听端口50051。完成server搭建