de.akquinet.jbosscc.guttenbase.export.AbstractExportDumpObject Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of GuttenBase Show documentation
Copying done right...
The newest version!
package de.akquinet.jbosscc.guttenbase.export;

import de.akquinet.jbosscc.guttenbase.connector.GuttenBaseException;
import org.apache.commons.io.IOUtils;

import java.io.*;

/**
 * Since CLOBs/BLOBs may be quite big. we do not load them into memory
 * completely, but read them in chunks and write the data to the output stream
 * in a loop.
 *
 * 
 * © 2012-2034 akquinet tech@spree
 * 
 *
 * @author M. Dahm
 */
public abstract class AbstractExportDumpObject implements Externalizable {
  private static final long serialVersionUID = 1L;

  public static final int DEFAULT_BUFFER_SIZE = 1024 * 1024 * 10;
  private transient final InputStream _inputStream;

  private transient File _tempFile;
  private transient FileInputStream _fileInputStream;

  public AbstractExportDumpObject() {
    this(null);
  }

  public AbstractExportDumpObject(final InputStream inputStream) {
    _inputStream = inputStream;
  }

  /**
   * Read data in chunks and write it to the outputstream to avoid out of memory
   * errors.
   */
  @Override
  public void writeExternal(final ObjectOutput output) throws IOException {
    final byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];

    for (int n = _inputStream.read(buffer); n > 0; n = _inputStream.read(buffer)) {
      byte[] buf = buffer;

      if (n < DEFAULT_BUFFER_SIZE) {
        buf = new byte[n];
        System.arraycopy(buffer, 0, buf, 0, n);
      }

      output.writeObject(buf);
      output.flush();
    }

    output.writeObject(null);
  }

  /**
   * Store read data in temporary file to avoid out of memory errors.
   */
  @Override
  public void readExternal(final ObjectInput input) throws IOException, ClassNotFoundException {
    if (_tempFile == null) {
      _tempFile = File.createTempFile("GB-DUMP-", null);
      _tempFile.deleteOnExit();
    }

    final FileOutputStream fileOutputStream = new FileOutputStream(_tempFile);

    for (byte[] buffer = (byte[]) input.readObject(); buffer != null; buffer = (byte[]) input.readObject()) {
      fileOutputStream.write(buffer, 0, buffer.length);
    }

    fileOutputStream.close();
  }

  public long length() {
    return _tempFile.length();
  }

  public byte[] getBytes(final long pos, final int length) {
    try {
      final InputStream inputStream = getBinaryStream(pos, length);
      final byte[] bytes = new byte[length];
      inputStream.read(bytes);
      inputStream.close();

      return bytes;
    } catch (final IOException e) {
      throw new GuttenBaseException("getBytes", e);
    }
  }

  public InputStream getBinaryStream() {
    return getBinaryStream(0, length());
  }

  public InputStream getBinaryStream(final long pos, @SuppressWarnings("unused") final long length) {
    try {
      _fileInputStream = new FileInputStream(_tempFile);
      _fileInputStream.skip(pos);
      return _fileInputStream;
    } catch (final IOException e) {
      throw new GuttenBaseException("getBinaryStream", e);
    }
  }

  public final void free() {
    if (_tempFile != null && _tempFile.exists()) {
      _tempFile.delete();
      _tempFile = null;
    }

    if (_fileInputStream != null) {
      IOUtils.closeQuietly(_fileInputStream);
      _fileInputStream = null;
    }
  }
}