import org.apache.hadoop.contrib.bkjournal.BKJournalProtos.EditLogLedgerProto; //导入依赖的package包/类
void write(ZooKeeper zkc, String path)
    throws IOException, KeeperException.NodeExistsException {
  this.zkPath = path;

  EditLogLedgerProto.Builder builder = EditLogLedgerProto.newBuilder();
  builder.setDataLayoutVersion(dataLayoutVersion)
    .setLedgerId(ledgerId).setFirstTxId(firstTxId);

  if (!inprogress) {
    builder.setLastTxId(lastTxId);
  }
  try {
    zkc.create(path, TextFormat.printToString(builder.build()).getBytes(UTF_8),
               Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT);
  } catch (KeeperException.NodeExistsException nee) {
    throw nee;
  } catch (KeeperException e) {
    throw new IOException("Error creating ledger znode", e);
  } catch (InterruptedException ie) {
    throw new IOException("Interrupted creating ledger znode", ie);
  }
}
 

import org.apache.hadoop.contrib.bkjournal.BKJournalProtos.EditLogLedgerProto; //导入依赖的package包/类
static EditLogLedgerMetadata read(ZooKeeper zkc, String path)
    throws IOException, KeeperException.NoNodeException  {
  try {
    byte[] data = zkc.getData(path, false, null);

    EditLogLedgerProto.Builder builder = EditLogLedgerProto.newBuilder();
    if (LOG.isDebugEnabled()) {
      LOG.debug("Reading " + path + " data: " + new String(data, UTF_8));
    }
    TextFormat.merge(new String(data, UTF_8), builder);
    if (!builder.isInitialized()) {
      throw new IOException("Invalid/Incomplete data in znode");
    }
    EditLogLedgerProto ledger = builder.build();

    int dataLayoutVersion = ledger.getDataLayoutVersion();
    long ledgerId = ledger.getLedgerId();
    long firstTxId = ledger.getFirstTxId();
    if (ledger.hasLastTxId()) {
      long lastTxId = ledger.getLastTxId();
      return new EditLogLedgerMetadata(path, dataLayoutVersion,
                                       ledgerId, firstTxId, lastTxId);
    } else {
      return new EditLogLedgerMetadata(path, dataLayoutVersion,
                                       ledgerId, firstTxId);
    }
  } catch(KeeperException.NoNodeException nne) {
    throw nne;
  } catch(KeeperException ke) {
    throw new IOException("Error reading from zookeeper", ke);
  } catch (InterruptedException ie) {
    throw new IOException("Interrupted reading from zookeeper", ie);
  }
}