import org.apache.hadoop.hdfs.qjournal.protocolPB.QJournalProtocolTranslatorPB; //导入依赖的package包/类
protected QJournalProtocol createProxy() throws IOException {
  final Configuration confCopy = new Configuration(conf);
  
  // Need to set NODELAY or else batches larger than MTU can trigger 
  // 40ms nagling delays.
  confCopy.setBoolean(
      CommonConfigurationKeysPublic.IPC_CLIENT_TCPNODELAY_KEY,
      true);
  
  RPC.setProtocolEngine(confCopy,
      QJournalProtocolPB.class, ProtobufRpcEngine.class);
  return SecurityUtil.doAsLoginUser(
      new PrivilegedExceptionAction<QJournalProtocol>() {
        @Override
        public QJournalProtocol run() throws IOException {
          RPC.setProtocolEngine(confCopy,
              QJournalProtocolPB.class, ProtobufRpcEngine.class);
          QJournalProtocolPB pbproxy = RPC.getProxy(
              QJournalProtocolPB.class,
              RPC.getProtocolVersion(QJournalProtocolPB.class),
              addr, confCopy);
          return new QJournalProtocolTranslatorPB(pbproxy);
        }
      });
}