The structure of the generated Java gRPC classes
This project contains a basic gRPC service:
The project can generate the Java classes according to the .proto files defined in the project, and here is the class diagram of the greeting related classes together with generated classes:
From the above class diagram, there are several notes:
- The
GreetingClient,GreetingServerandGreetingServerImplclasses are project original classes. - The other classes are the generated
gRPCclasses. - There are three core parts of the generated classes together with their related classes:
GreetingRequest,GreetingResponseandGreetingServiceGrpc. - The
GreetingServiceGrpccontains some inner classes, and one of its inner class isGreetingServiceImplBase. - The
GreetingServiceImplBaseimplements theio.grpc.BindableServiceinterface1.
In addition, the handwritten GreetingServerImpl class extends the GreetingServiceGrpc.GreetingServiceImplBase inner class:
package greeting.server;
import com.proto.greeting.GreetingRequest;
import com.proto.greeting.GreetingResponse;
import com.proto.greeting.GreetingServiceGrpc;
import io.grpc.stub.StreamObserver;
public class GreetingServerImpl extends GreetingServiceGrpc.GreetingServiceImplBase {
@Override
public void greet(GreetingRequest request, StreamObserver<GreetingResponse> responseObserver) {
responseObserver.onNext(GreetingResponse.newBuilder()
.setResult("Hello : "+request.getFirstName()).build());
responseObserver.onCompleted();
}
}
And the GreetingServer uses the GreetingServerImpl:
package greeting.server;
import io.grpc.Server;
import io.grpc.ServerBuilder;
import io.grpc.protobuf.services.ProtoReflectionService;
import java.io.IOException;
public class GreetingServer {
public static void main(String[] args) throws IOException, InterruptedException {
int port = 50052;
Server server = ServerBuilder.forPort(port)
.addService(new GreetingServerImpl())
.addService(ProtoReflectionService.newInstance())
.build();
server.start();
System.out.println("Server started");
System.out.println("Listing on port : "+ port);
Runtime.getRuntime().addShutdownHook(new Thread(() -> {
System.out.println("Received Shutdown Request");
server.shutdown();
System.out.println("Server Stopped");
}));
server.awaitTermination();
}
}
Above is the structure of the generated Java gRPC classes.