使用Grpc+maven定义接口、发布服务、调用服务

项目使用maven构建，执行mvn compile 命令后，proto文件自动生成java文件，这个功能须要依赖相关编译插件。
1、pom.xml配置

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.test.grpcTest</groupId>
  <artifactId>grpc-api</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>``
  <name>grpc-api</name>
  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
  </properties>
  <dependencies>
<!-- 添加grpc相关依赖包 -->      
    <dependency>
            <groupId>io.grpc</groupId>
            <artifactId>grpc-netty</artifactId>
            <version>1.0.0</version>
        </dependency>
        <dependency>
            <groupId>io.grpc</groupId>
            <artifactId>grpc-protobuf</artifactId>
            <version>1.0.0</version>
        </dependency>
        <dependency>
            <groupId>io.grpc</groupId>
            <artifactId>grpc-stub</artifactId>
            <version>1.0.0</version>
        </dependency>
        <dependency>
                        <groupId>io.grpc</groupId>
                        <artifactId>grpc-all</artifactId>
                        <version>0.13.2</version>
                </dependency>
  </dependencies>
 <!-- proto自动生成java文件所需的编译插件 -->  
  <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:3.0.0:exe:${os.detected.classifier}</protocArtifact>
                    <pluginId>grpc-java</pluginId>
                    <pluginArtifact>io.grpc:protoc-gen-grpc-java:1.0.0:exe:${os.detected.classifier}</pluginArtifact>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>compile</goal>
                            <goal>compile-custom</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>
</project>

---

2、proto文档（IDL文档）编辑和编译成java文件

//指定proto3格式
syntax = "proto3";
//一些生成代码的设置
option java_multiple_files = false;//以非外部类模式生成
option java_package = "com.test.grpcTest.grpc_api";//所在包名
option java_outer_classname = "Grpc";//最外层类名称
message UnaryRequest{
    string serviceName = 1;
    string methodName = 2;
    bytes data = 3;
    string request_id = 4;//参数默认都为可选，若是没有赋值，那么接口中不会出现该参数，不会默认为null之类的
}
message UnaryResponse{
    string serviceName = 1;
    string methodName = 2;
    bytes data = 3;
    string request_id = 4;
}
service GrpcService{
    // 一对一服务请求
    rpc SendUnaryRequest(UnaryRequest) returns(UnaryResponse);
}

proto文件编辑好后，在项目根目录下执行 **mvn compile** 进行编译 。
若是使用maven编译proto文件，那么须要默认将proto文件放在 /src/main/proto/  路径下。
编译后生成的java文件在 target/generated-sources/  路径下。
将 java 文件拷贝到  /src/main/java/ 路径下。
项目文件结构以下：

3、服务端代码
在 /src/main/java/ 路径下新建目录 /server，存放服务端代码。

package com.test.grpcTest.grpc_api.server;
import com.test.grpcTest.grpc_api.GrpcServiceGrpc;
import com.test.grpcTest.grpc_api.UnaryRequest;
import com.test.grpcTest.grpc_api.UnaryResponse;
import com.google.protobuf.ByteString;
import io.grpc.Server;
import io.grpc.ServerBuilder;
import io.grpc.stub.StreamObserver;
import java.io.IOException;
//Grpc服务器对象
public class GrpcServer {
    private int port = 50051;//grpc服务端口
    private Server server;//grpc server
    public static void main(String[] args) throws IOException,InterruptedException {
        final GrpcServer server = new GrpcServer();
        server.start();
        server.blockUntilShutdown();
    }
    private void start() throws IOException {
        //指定grpc服务器端口、接口服务对象，启动grpc服务器
        server = ServerBuilder.forPort(port).addService(new GreeterImpl())
            .build().start();
        System.out.println("service start...");
        //添加停机逻辑
        Runtime.getRuntime().addShutdownHook(new Thread() {
            @Override
            public void run() {
                System.err.println("*** shutting down gRPC server since JVM is shutting down");
                GrpcServer.this.stop();
                System.err.println("*** server shut down");
            }
        });
    }
    private void blockUntilShutdown() throws InterruptedException {
        if (server != null) {
            server.awaitTermination();
        }
    }
    private void stop() {
        if (server != null) {
            server.shutdown();
        }
    }
//内部类，继承抽象类 GrpcServiceGrpc.GrpcServiceImplBase，
//并重写服务方法 sendUnaryRequest
    private class GreeterImpl extends GrpcServiceGrpc.GrpcServiceImplBase {
//UnaryRequest 客户端请求参数，
//StreamObserver<UnaryResponse> 返回给客户端的封装参数
        public void sendUnaryRequest(UnaryRequest request,StreamObserver<UnaryResponse> responseObserver) {
            ByteString message = request.getData();
            System.out.println("server, serviceName:" + request.getServiceName()
                + "; methodName:" + request.getMethodName()+"; datas:"+new String(message.toByteArray()));
            UnaryResponse.Builder builder = UnaryResponse.newBuilder();            builder.setServiceName("GrpcServiceResponse").setMethodName("sendUnaryResponse");
            responseObserver.onNext(builder.build());
            responseObserver.onCompleted();
        }
    }
}

服务端输出日志：

4、客户端代码

package com.test.grpcTest.grpc_api.client;
import java.util.concurrent.TimeUnit;
import com.test.grpcTest.grpc_api.GrpcServiceGrpc;
import com.test.grpcTest.grpc_api.UnaryRequest;
import com.test.grpcTest.grpc_api.UnaryResponse;
import com.google.protobuf.ByteString;
import io.grpc.ManagedChannel;
import io.grpc.ManagedChannelBuilder;
//grpc客户端类
public class GrpcClient {
    private final ManagedChannel channel;//客户端与服务器的通讯channel
    private final GrpcServiceGrpc.GrpcServiceBlockingStub blockStub;//阻塞式客户端存根节点
    public GrpcClient(String host, int port) {
        channel = ManagedChannelBuilder.forAddress(host, port).usePlaintext(true).build();//指定grpc服务器地址和端口初始化通讯channel
        blockStub = GrpcServiceGrpc.newBlockingStub(channel);//根据通讯channel初始化客户端存根节点
    }
    public void shutdown() throws InterruptedException{
        channel.shutdown().awaitTermination(5, TimeUnit.SECONDS);
    }
    //客户端方法
    public void sayHello(String str){
        //封装请求参数
        UnaryRequest request = UnaryRequest.newBuilder()            .setServiceName("GrpcServiceRequest").setMethodName("sendUnaryRequest").setData(ByteString.copyFrom(str.getBytes()))
            .build();
        //客户端存根节点调用grpc服务接口，传递请求参数
        UnaryResponse response = blockStub.sendUnaryRequest(request);
        System.out.println("client, serviceName:"+response.getServiceName()+"; methodName:"+response.getMethodName());
    }
    public static void main(String[] args) throws InterruptedException{
        //初始化grpc客户端对象
        GrpcClient client = new GrpcClient("127.0.0.1",50051);
        for(int i=0; i<5; i++){
            client.sayHello("client word:"+ i);
            Thread.sleep(3000);
        }
    }
}

客户端输出日志：