(2);
}
/**
* @return Returns a reader onto the previous version of this content
*/
protected ContentReader getExistingContentReader()
{
return existingContentReader;
}
/**
* Adds the listener after checking that the output stream isn't already in
* use.
*/
public synchronized void addListener(ContentStreamListener listener)
{
if (channel != null)
{
throw new RuntimeException("Channel is already in use");
}
listeners.add(listener);
}
/**
* A factory method for subclasses to implement that will ensure the proper
* implementation of the {@link ContentWriter#getReader()} method.
*
* Only the instance need be constructed. The required mimetype, encoding, etc
* will be copied across by this class.
*
*
* @return Returns a reader onto the location referenced by this instance.
* The instance must always be a new instance and never null.
* @throws ContentIOException
*/
protected abstract ContentReader createReader() throws ContentIOException;
/**
* Performs checks and copies required reader attributes
*/
public final ContentReader getReader() throws ContentIOException
{
if (!isClosed())
{
return null;
}
ContentReader reader = createReader();
if (reader == null)
{
throw new AlfrescoRuntimeException("ContentReader failed to create new reader: \n" +
" writer: " + this);
}
else if (reader.getContentUrl() == null || !reader.getContentUrl().equals(getContentUrl()))
{
throw new AlfrescoRuntimeException("ContentReader has different URL: \n" +
" writer: " + this + "\n" +
" new reader: " + reader);
}
// copy across common attributes
reader.setMimetype(this.getMimetype());
reader.setEncoding(this.getEncoding());
// done
if (logger.isDebugEnabled())
{
logger.debug("Writer spawned new reader: \n" +
" writer: " + this + "\n" +
" new reader: " + reader);
}
return reader;
}
/**
* An automatically created listener sets the flag
*/
public synchronized final boolean isClosed()
{
if (channel != null)
{
return !channel.isOpen();
}
else
{
return false;
}
}
/**
* Provides low-level access to write content to the repository.
*
* This is the only of the content writing methods that needs to be implemented
* by derived classes. All other content access methods make use of this in their
* underlying implementations.
*
* @return Returns a channel with which to write content
* @throws ContentIOException if the channel could not be opened
*/
protected abstract WritableByteChannel getDirectWritableChannel() throws ContentIOException;
/**
* Create a channel that performs callbacks to the given listeners.
*
* @param directChannel the result of {@link #getDirectWritableChannel()}
* @param listeners the listeners to call
* @return Returns a channel that executes callbacks
* @throws ContentIOException
*/
private WritableByteChannel getCallbackWritableChannel(
WritableByteChannel directChannel,
List listeners)
throws ContentIOException
{
WritableByteChannel callbackChannel = null;
if (directChannel instanceof FileChannel)
{
callbackChannel = getCallbackFileChannel((FileChannel) directChannel, listeners);
}
else
{
// introduce an advistor to handle the callbacks to the listeners
ChannelCloseCallbackAdvise advise = new ChannelCloseCallbackAdvise(listeners);
ProxyFactory proxyFactory = new ProxyFactory(directChannel);
proxyFactory.addAdvice(advise);
callbackChannel = (WritableByteChannel) proxyFactory.getProxy();
}
// done
if (logger.isDebugEnabled())
{
logger.debug("Created callback byte channel: \n" +
" original: " + directChannel + "\n" +
" new: " + callbackChannel);
}
return callbackChannel;
}
/**
* @see #getDirectWritableChannel()
* @see #getCallbackWritableChannel()
*/
public synchronized final WritableByteChannel getWritableChannel() throws ContentIOException
{
// this is a use-once object
if (channel != null)
{
throw new RuntimeException("A channel has already been opened");
}
WritableByteChannel directChannel = getDirectWritableChannel();
channel = getCallbackWritableChannel(directChannel, listeners);
// done
if (logger.isDebugEnabled())
{
logger.debug("Opened channel onto content: \n" +
" content: " + this + "\n" +
" channel: " + channel);
}
return channel;
}
/**
* @inheritDoc
*/
public FileChannel getFileChannel(boolean truncate) throws ContentIOException
{
/*
* By calling this method, clients indicate that they wish to make random
* changes to the file. It is possible that the client might only want
* to update a tiny proportion of the file (truncate == false) or
* start afresh (truncate == true).
*
* Where the underlying support is not present for this method, a temporary
* file will be used as a substitute. When the write is complete, the
* results are copied directly to the underlying channel.
*/
// get the underlying implementation's best writable channel
channel = getWritableChannel();
// now use this channel if it can provide the random access, otherwise spoof it
FileChannel clientFileChannel = null;
if (channel instanceof FileChannel)
{
// all the support is provided by the underlying implementation
clientFileChannel = (FileChannel) channel;
// copy over the existing content, if required
if (!truncate && existingContentReader != null)
{
ReadableByteChannel existingContentChannel = existingContentReader.getReadableChannel();
long existingContentLength = existingContentReader.getSize();
// copy the existing content
try
{
clientFileChannel.transferFrom(existingContentChannel, 0, existingContentLength);
// copy complete
if (logger.isDebugEnabled())
{
logger.debug("Copied content for random access: \n" +
" writer: " + this + "\n" +
" existing: " + existingContentReader);
}
}
catch (IOException e)
{
throw new ContentIOException("Failed to copy from existing content to enable random access: \n" +
" writer: " + this + "\n" +
" existing: " + existingContentReader,
e);
}
finally
{
try { existingContentChannel.close(); } catch (IOException e) {}
}
}
// debug
if (logger.isDebugEnabled())
{
logger.debug("Content writer provided direct support for FileChannel: \n" +
" writer: " + this);
}
}
else
{
// No random access support is provided by the implementation.
// Spoof it by providing a 2-stage write via a temp file
File tempFile = TempFileProvider.createTempFile("random_write_spoof_", ".bin");
final FileContentWriter spoofWriter = new FileContentWriter(
tempFile, // the file to write to
getExistingContentReader()); // this ensures that the existing content is pulled in
// Attach a listener
// - to ensure that the content gets loaded from the temp file once writing has finished
// - to ensure that the close call gets passed on to the underlying channel
ContentStreamListener spoofListener = new ContentStreamListener()
{
public void contentStreamClosed() throws ContentIOException
{
// the spoofed temp channel has been closed, so get a new reader for it
ContentReader spoofReader = spoofWriter.getReader();
FileChannel spoofChannel = spoofReader.getFileChannel();
// upload all the temp content to the real underlying channel
try
{
long spoofFileSize = spoofChannel.size();
spoofChannel.transferTo(0, spoofFileSize, channel);
}
catch (IOException e)
{
throw new ContentIOException("Failed to copy from spoofed temporary channel to permanent channel: \n" +
" writer: " + this + "\n" +
" temp: " + spoofReader,
e);
}
finally
{
try { spoofChannel.close(); } catch (Throwable e) {}
try
{
channel.close();
}
catch (IOException e)
{
throw new ContentIOException("Failed to close underlying channel", e);
}
}
}
};
spoofWriter.addListener(spoofListener);
// we now have the spoofed up channel that the client can work with
clientFileChannel = spoofWriter.getFileChannel(truncate);
// debug
if (logger.isDebugEnabled())
{
logger.debug("Content writer provided indirect support for FileChannel: \n" +
" writer: " + this + "\n" +
" temp writer: " + spoofWriter);
}
}
// the file is now available for random access
return clientFileChannel;
}
/**
* @see Channels#newOutputStream(java.nio.channels.WritableByteChannel)
*/
public OutputStream getContentOutputStream() throws ContentIOException
{
try
{
WritableByteChannel channel = getWritableChannel();
OutputStream is = new BufferedOutputStream(Channels.newOutputStream(channel));
// done
return is;
}
catch (Throwable e)
{
throw new ContentIOException("Failed to open stream onto channel: \n" +
" writer: " + this,
e);
}
}
/**
* @see ContentReader#getContentInputStream()
* @see #putContent(InputStream)
*/
public void putContent(ContentReader reader) throws ContentIOException
{
try
{
// get the stream to read from
InputStream is = reader.getContentInputStream();
// put the content
putContent(is);
}
catch (Throwable e)
{
throw new ContentIOException("Failed to copy reader content to writer: \n" +
" writer: " + this + "\n" +
" source reader: " + reader,
e);
}
}
public final void putContent(InputStream is) throws ContentIOException
{
try
{
OutputStream os = getContentOutputStream();
FileCopyUtils.copy(is, os); // both streams are closed
// done
}
catch (IOException e)
{
throw new ContentIOException("Failed to copy content from input stream: \n" +
" writer: " + this,
e);
}
}
public final void putContent(File file) throws ContentIOException
{
try
{
OutputStream os = getContentOutputStream();
FileInputStream is = new FileInputStream(file);
FileCopyUtils.copy(is, os); // both streams are closed
// done
}
catch (IOException e)
{
throw new ContentIOException("Failed to copy content from file: \n" +
" writer: " + this + "\n" +
" file: " + file,
e);
}
}
/**
* Makes use of the encoding, if available, to convert the string to bytes.
*
* @see ContentAccessor#getEncoding()
*/
public final void putContent(String content) throws ContentIOException
{
try
{
// attempt to use the correct encoding
String encoding = getEncoding();
byte[] bytes = (encoding == null) ? content.getBytes() : content.getBytes(encoding);
// get the stream
OutputStream os = getContentOutputStream();
ByteArrayInputStream is = new ByteArrayInputStream(bytes);
FileCopyUtils.copy(is, os); // both streams are closed
// done
}
catch (IOException e)
{
throw new ContentIOException("Failed to copy content from string: \n" +
" writer: " + this +
" content length: " + content.length(),
e);
}
}
}