GRPC入门及Server Client示范

GRPC

GRPC是谷歌google出的一款RPC框架，RPC是远程过程调用remote procedure call，就是像调用本地方法一样调用远程机器上的方法

提供被调用的方法写在xxx.proto文件中，然后我们利用maven的compile编译生成代码，然后将定义的那些方法实现即可。绑定端口启动服务器即可提供这些方法被需要的人调用。

调用者使用stub来调用这些方法，返回结果。

• demo项目结构

• Test.proto文件

  syntax = "proto3";
  
  option java_multiple_files = true;
  option java_package = "com.example.grpc_java_demo";
  option java_outer_classname = "Test";
  option objc_class_prefix = "xlf";
  
  package test;
  
  //定义服务
  service TestService {
      //注意：这里是returns 不是return
      rpc SayHello(Request) returns (Response){
  
      }
  }
  //定义参数类型
  message Request {
      string message=1;
  }
  message Response {
      string message=1;
  }
  
  
  

• 服务提供端类

  package com.example.grpc_java_demo.server;
  
  
  import com.example.grpc_java_demo.*;
  import com.google.protobuf.Descriptors;
  import io.grpc.Server;
  import io.grpc.ServerBuilder;
  import io.grpc.stub.StreamObserver;
  
  import java.io.IOException;
  import java.util.Map;
  
  /**
   * 服务端
   */
  public class TestServer {
      //定义端口
      private final int port = 50051;
      //服务
      private Server server;
  
      //启动服务,并且接受请求
      private void start() throws IOException {
          server = ServerBuilder.forPort(port).addService(new TestImpl()).build().start();
          System.out.println("服务开始启动-------");
          Runtime.getRuntime().addShutdownHook(new Thread() {
              @Override
              public void run() {
                  System.err.println("------shutting down gRPC server since JVM is shutting down-------");
                  System.err.println("调用者断开连接");
                  TestServer.this.stop();
                  System.err.println("------server shut down------");
              }
          });
      }
  
      //stop服务
      private void stop() {
          if (server != null) {
              server.shutdown();
          }
      }
      //server阻塞到程序退出
      private void  blockUntilShutdown() throws InterruptedException {
          if (server!=null){
              server.awaitTermination();
          }
      }
  
      //实现服务接口的类
      private class TestImpl extends TestServiceGrpc.TestServiceImplBase {
          @Override
          public void sayHello(Request request, StreamObserver<Response> responseObserver) {
              String msg=request.getMessage()+"我是服务器";
              System.err.println("收到请求："+request.getMessage()+" 回复："+msg);
              Response build = Response.newBuilder().setMessage(msg).build();
              //onNext()方法向客户端返回结果
              responseObserver.onNext(build);
              //告诉客户端这次调用已经完成
              responseObserver.onCompleted();
          }
      }
      public static void main(String[] args) throws IOException, InterruptedException {
          final  TestServer server=new TestServer();
          server.start();
          server.blockUntilShutdown();
      }
  }
  
  
  

• 调用端client

  构建所需参数，调用stub里的方法即可完成。

  package com.example.grpc_java_demo.client;
  
  import com.example.grpc_java_demo.*;
  import io.grpc.ManagedChannel;
  import io.grpc.ManagedChannelBuilder;
  
  import java.util.concurrent.TimeUnit;
  /**
   * 客户端
   */
  public class TestClient {
      private final ManagedChannel channel;
      private final TestServiceGrpc.TestServiceBlockingStub blockingStub;
      private static final String host="127.0.0.1";
      private static final int ip=50051;
      public TestClient(String host,int port){
          //usePlaintext表示明文传输，否则需要配置ssl
          //channel  表示通信通道
          channel= ManagedChannelBuilder.forAddress(host, port).usePlaintext(true).build();
          //存根
          blockingStub=TestServiceGrpc.newBlockingStub(channel);
      }
      public void shutdown() throws InterruptedException {
          channel.shutdown().awaitTermination(5, TimeUnit.SECONDS);
      }
      public void  sayHello(){
          String msg="你好";
          System.err.println("发送："+msg);
          Request request=Request.newBuilder().setMessage(msg).build();
          Response response=blockingStub.sayHello(request);
          System.err.println("收到回复："+response.getMessage());
      }
      public static void main(String[] args) throws InterruptedException {
          TestClient client=new TestClient(host,ip);
          client.sayHello();
          client.shutdown();
      }
  }
  
  

  服务器收到的请求参数：

  

  调用者收到的回复