import org.apache.hadoop.ipc.ProtobufRpcEngine.RpcRequestMessageWrapper; //导入依赖的package包/类
@Override
public void write(byte[] buf, int off, int len) throws IOException {
  if (LOG.isDebugEnabled()) {
    LOG.debug("wrapping token of length:" + len);
  }
  buf = saslClient.wrap(buf, off, len);
  RpcSaslProto saslMessage = RpcSaslProto.newBuilder()
      .setState(SaslState.WRAP)
      .setToken(ByteString.copyFrom(buf, 0, buf.length))
      .build();
  RpcRequestMessageWrapper request =
      new RpcRequestMessageWrapper(saslHeader, saslMessage);
  DataOutputStream dob = new DataOutputStream(out);
  dob.writeInt(request.getLength());
  request.write(dob);
 }
 

import org.apache.hadoop.ipc.ProtobufRpcEngine.RpcRequestMessageWrapper; //导入依赖的package包/类
private void writeConnectionContext(ConnectionId remoteId,
                                    AuthMethod authMethod)
                                        throws IOException {
  // Write out the ConnectionHeader
  IpcConnectionContextProto message = ProtoUtil.makeIpcConnectionContext(
      RPC.getProtocolName(remoteId.getProtocol()),
      remoteId.getTicket(),
      authMethod);
  RpcRequestHeaderProto connectionContextHeader = ProtoUtil
      .makeRpcRequestHeader(RpcKind.RPC_PROTOCOL_BUFFER,
          OperationProto.RPC_FINAL_PACKET, CONNECTION_CONTEXT_CALL_ID,
          RpcConstants.INVALID_RETRY_COUNT, clientId);
  RpcRequestMessageWrapper request =
      new RpcRequestMessageWrapper(connectionContextHeader, message);
  
  // Write out the packet length
  out.writeInt(request.getLength());
  request.write(out);
}
 

import org.apache.hadoop.ipc.ProtobufRpcEngine.RpcRequestMessageWrapper; //导入依赖的package包/类
private void sendSaslMessage(DataOutputStream out, RpcSaslProto message)
    throws IOException {
  if (LOG.isDebugEnabled()) {
    LOG.debug("Sending sasl message "+message);
  }
  RpcRequestMessageWrapper request =
      new RpcRequestMessageWrapper(saslHeader, message);
  out.writeInt(request.getLength());
  request.write(out);
  out.flush();    
}