| java.lang.Object
 java.io.OutputStream
org.apache.commons.io.output.ThresholdingOutputStream
org.apache.commons.io.output.DeferredFileOutputStream
| DeferredFileOutputStream | | public class DeferredFileOutputStream extends ThresholdingOutputStream (Code) | | An output stream which will retain data in memory until a specified
threshold is reached, and only then commit it to disk. If the stream is
closed before the threshold is reached, the data will not be written to
disk at all.
This class originated in FileUpload processing. In this use case, you do
not know in advance the size of the file being uploaded. If the file is small
you want to store it in memory (for speed), but if the file is large you want
to store it to file (to avoid memory issues).
author:
Martin Cooper
author:
gaxzerow
version:
$Id: DeferredFileOutputStream.java 437567 2006-08-28 06:39:07Z bayard $ |
| Constructor Summary | |
| public | DeferredFileOutputStream(int threshold, File outputFile)
Constructs an instance of this class which will trigger an event at the
specified threshold, and save data to a file beyond that point. |
| Method Summary | |
| public void | close()
| | public byte[] | getData()
Returns the data for this output stream as an array of bytes, assuming
that the data has been retained in memory. | | public File | getFile()
Returns the same output file specified in the constructor, even when
threashold has not been reached. | | protected OutputStream | getStream()
Returns the current output stream. | | public boolean | isInMemory()
Determines whether or not the data for this output stream has been
retained in memory. | | protected void | thresholdReached()
Switches the underlying output stream from a memory based stream to one
that is backed by disk. | | public void | writeTo(OutputStream out)
Writes the data from this output stream to the specified output stream,
after it has been closed. |
| DeferredFileOutputStream | | public DeferredFileOutputStream(int threshold, File outputFile)(Code) | | Constructs an instance of this class which will trigger an event at the
specified threshold, and save data to a file beyond that point.
Parameters:
threshold - The number of bytes at which to trigger an event.
Parameters:
outputFile - The file to which data is saved beyond the threshold. |
| close | | public void close() throws IOException(Code) | | Closes underlying output stream, and mark this as closed
exception:
IOException - if an error occurs. |
| getData | | public byte[] getData()(Code) | | Returns the data for this output stream as an array of bytes, assuming
that the data has been retained in memory. If the data was written to
disk, this method returns null.
The data for this output stream, or null if no suchdata is available. |
| getFile | | public File getFile()(Code) | | Returns the same output file specified in the constructor, even when
threashold has not been reached.
The file for this output stream, or null if no suchfile exists. |
| getStream | | protected OutputStream getStream() throws IOException(Code) | | Returns the current output stream. This may be memory based or disk
based, depending on the current state with respect to the threshold.
The underlying output stream.
exception:
IOException - if an error occurs. |
| isInMemory | | public boolean isInMemory()(Code) | | Determines whether or not the data for this output stream has been
retained in memory.
true if the data is available in memory;false otherwise. |
| thresholdReached | | protected void thresholdReached() throws IOException(Code) | | Switches the underlying output stream from a memory based stream to one
that is backed by disk. This is the point at which we realise that too
much data is being written to keep in memory, so we elect to switch to
disk-based storage.
exception:
IOException - if an error occurs. |
| writeTo | | public void writeTo(OutputStream out) throws IOException(Code) | | Writes the data from this output stream to the specified output stream,
after it has been closed.
Parameters:
out - output stream to write to.
exception:
IOException - if this stream is not yet closed or an error occurs. |
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