我正在尝试使用 gRPC 和 ProtoBuf 将图像从 Java 客户端发送到 Python 服务器。我将图像编码为 ByteString 并使用blockingStub 发送它。 Python 服务器接收 ProtoBuf,但 Java ByteString 现在是 Python str。我不知道如何从 str 恢复图像。
当我调用服务器时:
request.ParseFromString(request.png_encoded) # Throws error
它引发:
Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/grpc/_server.py", line 364, in _call_behavior
return behavior(argument, context), True
File "process_server.py", line 57, in Process request.ParseFromString(request.png_encoded)
File "/usr/local/lib/python2.7/dist-packages/google/protobuf/message.py", line 185, in ParseFromString self.MergeFromString(serialized)
File "/usr/local/lib/python2.7/dist-packages/google/protobuf/internal/python_message.py", line 1082, in MergeFromString if self._InternalParse(serialized, 0, length) != length:
File "/usr/local/lib/python2.7/dist-packages/google/protobuf/internal/python_message.py", line 1108, in InternalParse new_pos = local_SkipField(buffer, new_pos, end, tag_bytes)
File "/usr/local/lib/python2.7/dist-packages/google/protobuf/internal/decoder.py", line 850, in SkipField return WIRETYPE_TO_SKIPPER[wire_type](buffer, pos, end)
File "/usr/local/lib/python2.7/dist-packages/google/protobuf/internal/decoder.py", line 820, in _RaiseInvalidWireType
raise _DecodeError('Tag had invalid wire type.')
DecodeError: Tag had invalid wire type.
Java 客户端:
public void run_process(String imPath) {
logger.info("Will try to retrieve boxes with image " + imPath + " ...");
File path = new File(imPath);
byte[] imageInByte = null;
ByteString byteIm = null;
try {
BufferedImage bufferedIm = null;
ByteArrayOutputStream out = new ByteArrayOutputStream();
bufferedIm = ImageIO.read(path);
ImageIO.write(bufferedIm, "png", out);
out.flush();
imageInByte = out.toByteArray();
out.close();
ByteBuffer buf = ByteBuffer.wrap(imageInByte);
byteIm = ByteString.copyFrom(buf);
} catch (IOException e) {
e.printStackTrace();
}
private final ManagedChannel channel;
channel = ManagedChannelBuilder.forAddress("localhost", 50051).usePlaintext(true).build();
private final ProcessServiceGrpc.ProcessServiceBlockingStub blockingStub;
blockingStub = ProcessServiceGrpc.newBlockingStub(channel);
ProcessRequest request = ProcessRequest.newBuilder().setPngEncoded(byteIm).build();
ProcessResponse response;
try {
response = blockingStub.process(request);
} catch (StatusRuntimeException e) {
logger.log(Level.WARNING, "RPC failed: {0}", e.getStatus());
return;
}
logger.info("Boxes retrieved: " + response.toString());
}
Python 服务器:
def Process(self, request, context):
print(type(request.png_encoded)) # prints <type 'str'>
request.ParseFromString(request.png_encoded) # Throws error
# Return empty response for now
process_response = inference_pb2.ProcessResponse()
return process_response
def serve():
server = grpc.server(futures.ThreadPoolExecutor(max_workers=10))
inference_pb2.add_ProcessServiceServicer_to_server(
ProcessServiceServicer(), server)
print "Starting Process Server"
server.add_insecure_port('localhost:50051')
server.start()
try:
while True:
time.sleep(_ONE_DAY_IN_SECONDS)
except KeyboardInterrupt:
server.stop(0)
if __name__ == '__main__':
serve()
我尝试用谷歌搜索“Decode Java Protobuf in Python”和“decode java protobuf Bytestring in python”,但没有成功。提前致谢!
最佳答案
Java 中的
ByteString
只是一个不可变的 byte[]
。 Python 2 中的等效项是 str
。它是一个二进制表示形式。如果您想将图像保存到磁盘,您可以:
with open('out.png', 'wb') as file:
file.write(request.png_encoded)
关于java - gRPC——在 Protobuf 中将 .png 图像从 Java 客户端发送到 Python 服务器,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/39238838/