File	Doc	Category	Size	Date	Package
DeferredFileOutputStream.java	API Doc	Apache Tomcat 6.0.14	5568	Fri Jul 20 04:20:30 BST 2007	org.apache.tomcat.util.http.fileupload

DeferredFileOutputStream

• java.lang.Object
  • ThresholdingOutputStream

Fields Summary
private ByteArrayOutputStream	memoryOutputStream The output stream to which data will be written prior to the theshold being reached.
private FileOutputStream	diskOutputStream The output stream to which data will be written after the theshold is reached.
private OutputStream	currentOutputStream The output stream to which data will be written at any given time. This will always be one of memoryOutputStream or diskOutputStream.
private File	outputFile The file to which output will be directed if the threshold is exceeded.

Constructors 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. param threshold The number of bytes at which to trigger an event. param outputFile The file to which data is saved beyond the threshold. super(threshold); this.outputFile = outputFile; memoryOutputStream = new ByteArrayOutputStream(threshold); currentOutputStream = memoryOutputStream;

Methods Summary
public byte[]	getData() 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. return The data for this output stream, or null if no such data is available. if (memoryOutputStream != null) { return memoryOutputStream.toByteArray(); } return null;
public java.io.File	getFile() Returns the data for this output stream as a File, assuming that the data was written to disk. If the data was retained in memory, this method returns null. return The file for this output stream, or null if no such file exists. return outputFile;
protected java.io.OutputStream	getStream() Returns the current output stream. This may be memory based or disk based, depending on the current state with respect to the threshold. return The underlying output stream. exception IOException if an error occurs. return currentOutputStream;
public boolean	isInMemory() Determines whether or not the data for this output stream has been retained in memory. return true if the data is available in memory; false otherwise. return (!isThresholdExceeded());
protected void	thresholdReached() 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. byte[] data = memoryOutputStream.toByteArray(); FileOutputStream fos = new FileOutputStream(outputFile); fos.write(data); diskOutputStream = fos; currentOutputStream = fos; memoryOutputStream = null;