org.alfresco.repo.content
Class EmptyContentReader

java.lang.Object
  extended by org.alfresco.repo.content.AbstractContentAccessor
      extended by org.alfresco.repo.content.AbstractContentReader
          extended by org.alfresco.repo.content.EmptyContentReader
All Implemented Interfaces:
ContentAccessor, ContentReader

public class EmptyContentReader
extends AbstractContentReader

A blank reader for which exists() always returns false.


Nested Class Summary
 
Nested classes/interfaces inherited from class org.alfresco.repo.content.AbstractContentAccessor
AbstractContentAccessor.CallbackFileChannel, AbstractContentAccessor.ChannelCloseCallbackAdvise
 
Constructor Summary
EmptyContentReader(java.lang.String contentUrl)
           
 
Method Summary
protected  ContentReader createReader()
          A factory method for subclasses to implement that will ensure the proper implementation of the ContentReader.getReader() method.
 boolean exists()
          Check if the underlying content is present.
protected  java.nio.channels.ReadableByteChannel getDirectReadableChannel()
          Provides low-level access to read content from the repository.
 long getLastModified()
          Gets the time of the last modification of the underlying content.
 long getSize()
          Gets the size of the content that this reader references.
 
Methods inherited from class org.alfresco.repo.content.AbstractContentReader
addListener, compareContentReaders, getContent, getContent, getContentInputStream, getContentString, getContentString, getFileChannel, getReadableChannel, getReader, isChannelOpen, isClosed
 
Methods inherited from class org.alfresco.repo.content.AbstractContentAccessor
channelOpened, finalize, getCallbackFileChannel, getContentData, getContentUrl, getEncoding, getLocale, getMimetype, setContentUrl, setEncoding, setLocale, setMimetype, setRetryingTransactionHelper, toString
 
Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface org.alfresco.service.cmr.repository.ContentAccessor
getContentData, getContentUrl, getEncoding, getLocale, getMimetype, setEncoding, setLocale, setMimetype, setRetryingTransactionHelper
 

Constructor Detail

EmptyContentReader

public EmptyContentReader(java.lang.String contentUrl)
Parameters:
contentUrl - the content URL
Method Detail

createReader

protected ContentReader createReader()
                              throws ContentIOException
Description copied from class: AbstractContentReader
A factory method for subclasses to implement that will ensure the proper implementation of the ContentReader.getReader() method.

Only the instance need be constructed. The required mimetype, encoding, etc will be copied across by this class.

Specified by:
createReader in class AbstractContentReader
Returns:
Returns an instance of the this class
Throws:
ContentIOException

getDirectReadableChannel

protected java.nio.channels.ReadableByteChannel getDirectReadableChannel()
                                                                  throws ContentIOException
Description copied from class: AbstractContentReader
Provides low-level access to read content from the repository.

This is the only of the content reading methods that needs to be implemented by derived classes. All other content access methods make use of this in their underlying implementations.

Specified by:
getDirectReadableChannel in class AbstractContentReader
Returns:
Returns a channel from which content can be read
Throws:
ContentIOException - if the channel could not be opened or the underlying content has disappeared

exists

public boolean exists()
Description copied from interface: ContentReader
Check if the underlying content is present.

Returns:
Returns true if there is content at the URL refered to by this reader

getLastModified

public long getLastModified()
Description copied from interface: ContentReader
Gets the time of the last modification of the underlying content.

Returns:
Returns the last modification time using the standard long time, or 0L if the content doesn't exist.
See Also:
System.currentTimeMillis()

getSize

public long getSize()
Description copied from interface: ContentAccessor
Gets the size of the content that this reader references.

Returns:
Returns the document byte length, or OL if the content doesn't exist.


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