ProtobufTypeUtil.java 文件源码

/**
 * Generates a protobuf descriptor instance from a FileDescriptor set.
 *
 * @param set               set of file descriptors
 * @param fileDescriptorMap map of message types to file descriptors
 * @param descriptorFile    descriptor file for message to be decoded
 * @param qualifiedMessageType       the name of the message to be decoded
 * @return protobuf descriptor instance
 * @throws StageException
 */
public static Descriptors.Descriptor getDescriptor(
    DescriptorProtos.FileDescriptorSet set,
    Map<String, Descriptors.FileDescriptor> fileDescriptorMap,
    String descriptorFile,
    String qualifiedMessageType
) throws StageException {

  // find the FileDescriptorProto which contains the message type
  // IF cannot find, then bail out
  String packageName = null;
  String messageType = qualifiedMessageType;
  int lastIndex = qualifiedMessageType.lastIndexOf('.');
  if (lastIndex != -1) {
    packageName = qualifiedMessageType.substring(0, lastIndex);
    messageType = qualifiedMessageType.substring(lastIndex + 1);
  }
  DescriptorProtos.FileDescriptorProto file = getFileDescProtoForMsgType(packageName, messageType, set);
  if (file == null) {
    // could not find the message type from all the proto files contained in the descriptor file
    throw new StageException(Errors.PROTOBUF_00, qualifiedMessageType, descriptorFile);
  }
  // finally get the FileDescriptor for the message type
  Descriptors.FileDescriptor fileDescriptor = fileDescriptorMap.get(file.getName());
  // create builder using the FileDescriptor
  // this can only find the top level message types
  return fileDescriptor.findMessageTypeByName(messageType);

}