SourceForwarder.java :  » XML » wo-flint » org » weborganic » flint » content » Java Open Source

package org.weborganic.flint.content;

import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.weborganic.flint.IndexException;

/**
 * A simple translator implementation allows XML Media types to be simply forwarded without translation.
 * 
 * @author Jean-Baptiste Reure
 * @version 10 March 2010
 */
public final class SourceForwarder implements ContentTranslator {

  /**
   * The list of media types.
   */
  private final List<String> _mediaTypes;

  /**
   * The charset to use to decode byte streams.
   */
  private final Charset _charset;

  /**
   * Forwards data for one MIME type only, will return in any other case.
   * 
   * @param mediaType The Media type that this translator can forward.
   * @param charset   The name of the charset to use for decoding byte streams.
   * 
   * @throws IllegalCharsetNameException If the given charset name is illegal.
   * @throws IllegalArgumentException    If the given charset name or media type is <code>null</code>.
   * @throws UnsupportedCharsetException If no support for the named charset is available.
   */
  public SourceForwarder(String mediaType, String charset) throws IllegalArgumentException {
    this(mediaType, Charset.forName(charset));
  }

  /**
   * Forwards data for one MIME type only, will return in any other case.
   * 
   * @param mediaTypes The list of Media types this translator should forward.
   * @param charset    The name of the charset to use for decoding byte streams.
   * 
   * @throws IllegalCharsetNameException If the given charset name is illegal.
   * @throws IllegalArgumentException    If the given charset name or media type is <code>null</code>.
   * @throws UnsupportedCharsetException If no support for the named charset is available.
   */
  public SourceForwarder(List<String> mediaTypes, String charset) throws IllegalArgumentException {
    this(mediaTypes, Charset.forName(charset));
  }

  /**
   * Forwards data for one MIME type only, will return in any other case.
   * 
   * @param mediaType The Media type that this translator can forward.
   * @param charset   The charset to use for decoding byte streams.
   * 
   * @throws IllegalArgumentException    If the given charset name or media type is <code>null</code>.
   */
  public SourceForwarder(String mediaType, Charset charset) throws IllegalArgumentException {
    if (mediaType == null) throw new IllegalArgumentException("mediaType is null");
    if (charset == null) throw new IllegalArgumentException("charset is null");
    this._mediaTypes = Collections.singletonList(mediaType);
    this._charset = charset;
  }

  /**
   * Forwards data for one MIME type only, will return in any other case.
   * 
   * @param mediaTypes The list of Media types this translator should forward.
   * @param charset    The charset to use for decoding byte streams.
   * 
   * @throws IllegalArgumentException    If the given charset name or media type is <code>null</code>.
   */
  public SourceForwarder(List<String> mediaTypes, Charset charset) throws IllegalArgumentException {
    if (mediaTypes == null) throw new IllegalArgumentException("mediaTypes is null");
    if (charset == null) throw new IllegalArgumentException("charset is null");
    this._mediaTypes = new ArrayList<String>(mediaTypes);
    this._charset = charset;
  }

  /**
   * Returns a new {@link Reader} on the content to translate using the specified charset.
   * 
   * @param content The content to translate.
   * 
   * @return the reader or <code>null</code> if this forwarder does not support this Media type.
   * 
   * @throws IndexException If thrown while trying to access the content methods.
   */
  public Reader translate(Content content) throws IndexException {
    // Ignore deleted content
    if (content.isDeleted()) return null;
    // Check that Media type is supported
    if (!this._mediaTypes.contains(content.getMediaType())) return null;
    // Return a new reader
    return new InputStreamReader(content.getSource(), this._charset);
  }

}