import org.apache.hadoop.hdfs.qjournal.server.GetJournalEditServlet; //导入依赖的package包/类
@Override
public URL buildURLToFetchLogs(long segmentTxId, long position) {
  Preconditions.checkArgument(segmentTxId > -1,
      "Invalid segment: %s", segmentTxId);
  Preconditions.checkState(httpPort != -1,
      "HTTP port not set yet");
      
  try {
    String path = GetJournalEditServlet.buildPath(
        journalId, segmentTxId, nsInfo, position);
    return new URL("http", addr.getAddress().getHostAddress(), httpPort, path.toString());
  } catch (MalformedURLException e) {
    // should never get here.
    throw new IllegalStateException(e);
  }
}
 

import org.apache.hadoop.hdfs.qjournal.server.GetJournalEditServlet; //导入依赖的package包/类
@Override
public URL buildURLToFetchLogs(long segmentTxId) {
  Preconditions.checkArgument(segmentTxId > 0,
      "Invalid segment: %s", segmentTxId);
  Preconditions.checkState(httpPort != -1,
      "HTTP port not set yet");
      
  try {
    String path = GetJournalEditServlet.buildPath(
        journalId, segmentTxId, nsInfo);
    return new URL("http", addr.getHostName(), httpPort, path.toString());
  } catch (MalformedURLException e) {
    // should never get here.
    throw new RuntimeException(e);
  }
}
 

import org.apache.hadoop.hdfs.qjournal.server.GetJournalEditServlet; //导入依赖的package包/类
@Override
public URL buildURLToFetchLogs(long segmentTxId) {
  Preconditions.checkArgument(segmentTxId > 0,
      "Invalid segment: %s", segmentTxId);
  Preconditions.checkState(hasHttpServerEndPoint(), "No HTTP/HTTPS endpoint");
      
  try {
    String path = GetJournalEditServlet.buildPath(
        journalId, segmentTxId, nsInfo);
    return new URL(httpServerURL, path);
  } catch (MalformedURLException e) {
    // should never get here.
    throw new RuntimeException(e);
  }
}
 

import org.apache.hadoop.hdfs.qjournal.server.GetJournalEditServlet; //导入依赖的package包/类
public InputStream getInputStream(long position) throws IOException {
  url = logger.buildURLToFetchLogs(firstTxId, position);
  
  HttpURLConnection connection = (HttpURLConnection)url.openConnection();
  
  // set timeout for connecting and reading
  connection.setConnectTimeout(httpTimeout);
  connection.setReadTimeout(httpTimeout);
  
  if (connection.getResponseCode() != HttpURLConnection.HTTP_OK) {
    throw new IOException(
        "Fetch of " + url +
        " failed with status code " + connection.getResponseCode() +
        "\nResponse message:\n" + connection.getResponseMessage());
  }

  String contentLength = connection.getHeaderField(CONTENT_LENGTH);
  if (contentLength != null) {
    advertisedSize = Long.parseLong(contentLength);
    if (advertisedSize < 0) {
      throw new IOException("Invalid " + CONTENT_LENGTH + " header: " +
          contentLength);
    }
  } else {
    throw new IOException(CONTENT_LENGTH + " header is not provided " +
                          "by the server when trying to fetch " + url);
  }
  
  String lastValidTxIdStr = connection.getHeaderField(GetJournalEditServlet.LAST_VALID_TXID);
  if (lastValidTxIdStr == null) {
    throw new IOException(GetJournalEditServlet.LAST_VALID_TXID + " is not provided");
  }
  
  String isInProgressStr = connection.getHeaderField(GetJournalEditServlet.IS_IN_PROGRESS);
  if (isInProgressStr == null) {
    throw new IOException(GetJournalEditServlet.IS_IN_PROGRESS + " is not provided");
  }
  
  isInProgress = Boolean.valueOf(isInProgressStr);
  lastValidTxId = Long.valueOf(lastValidTxIdStr);
  startPosition = position;
  return connection.getInputStream();
}