Java中的gRPC -如何接收文件内容作为响应

syntax = "proto3";

message FileRequest {
  // 定义请求消息类型
  string fileName = 1;
}

message FileResponse {
  // 定义响应消息类型
  bytes fileContent = 1;
}

service FileService {
  // 定义RPC方法
  rpc getFileContent(FileRequest) returns (FileResponse) {}
}

protoc --java_out=. file.proto

import io.grpc.Server;
import io.grpc.ServerBuilder;
import io.grpc.stub.StreamObserver;

public class FileServer {
  public static void main(String[] args) throws Exception {
    Server server = ServerBuilder.forPort(8080)
        .addService(new FileServiceImpl())
        .build();

    server.start();
    server.awaitTermination();
  }

  static class FileServiceImpl extends FileServiceGrpc.FileServiceImplBase {
    @Override
    public void getFileContent(FileRequest request, StreamObserver<FileResponse> responseObserver) {
      // 读取文件内容并构建响应
      try {
        byte[] fileContent = readFile(request.getFileName());
        FileResponse response = FileResponse.newBuilder()
            .setFileContent(ByteString.copyFrom(fileContent))
            .build();
        responseObserver.onNext(response);
        responseObserver.onCompleted();
      } catch (IOException e) {
        responseObserver.onError(e);
      }
    }

    private byte[] readFile(String fileName) throws IOException {
      // 读取文件内容的实现逻辑
    }
  }
}

import io.grpc.ManagedChannel;
import io.grpc.ManagedChannelBuilder;
import io.grpc.stub.StreamObserver;

public class FileClient {
  public static void main(String[] args) {
    ManagedChannel channel = ManagedChannelBuilder.forAddress("localhost", 8080)
        .usePlaintext()
        .build();

    FileServiceGrpc.FileServiceStub stub = FileServiceGrpc.newStub(channel);

    FileRequest request = FileRequest.newBuilder()
        .setFileName("example.txt")
        .build();

    stub.getFileContent(request, new StreamObserver<FileResponse>() {
      @Override
      public void onNext(FileResponse response) {
        // 处理响应，获取文件内容
        byte[] fileContent = response.getFileContent().toByteArray();
        // 处理文件内容的逻辑
      }

      @Override
      public void onError(Throwable t) {
        // 处理错误
      }

      @Override
      public void onCompleted() {
        // 完成操作
      }
    });
  }
}