com.rt.web.multipart.GOutputStream Maven / Gradle / Ivy
package com.rt.web.multipart;
import org.apache.commons.io.output.ThresholdingOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
/**
* Important Note: This src is modified version of {@link org.apache.commons.io.output.DeferredFileOutputStream}
* to make it work in GAE and spring.
*
*
An output stream which will retain data in memory (always) as GAE doesn't suport file handling.
* If the stream reaches the threshold , the UnsupportedOperationException will be thrown.
* To fix, try changing the thresold limit.
*
*
* This class originated in FileUpload processing. In this use case, you do not know in advance the
* size of the file being uploaded.
* Anyways, the file is stored in memory (for speed and GAE doesn't support file handling.)
*
* @author kernel164
* @author Martin Cooper
* @author gaxzerow
*/
public class GOutputStream extends ThresholdingOutputStream {
// ----------------------------------------------------------- Data members
/**
* The output stream to which data will be written prior to the theshold being reached.
*/
private final ByteArrayOutputStream memoryOutputStream;
/**
* True when close() has been called successfully.
*/
private boolean closed = false;
// ----------------------------------------------------------- Constructors
/**
* Constructs an instance of this class which will trigger throw
* UnsupportedOperationException if the specified threshold is reached.
*
* @param threshold The number of bytes at which to trigger an event.
*/
public GOutputStream(long threshold) {
super((int) threshold);
memoryOutputStream = new ByteArrayOutputStream();
}
// --------------------------------------- ThresholdingOutputStream methods
/**
* 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.
*/
@Override
protected OutputStream getStream() throws IOException {
return memoryOutputStream;
}
/**
* Not possible in GAE. Will never reach!!
* If it happens, try changing max upload size setting.
*/
@Override
protected void thresholdReached() {
throw new UnsupportedOperationException("Not possible in GAE. Will never reach!! Try changing max upload size setting.");
}
// --------------------------------------------------------- Public methods
/**
* Determines whether or not the data for this output stream has been retained in memory.
*
* @return always true
*/
public boolean isInMemory() {
return true;
}
/**
* Returns the data for this output stream as an array of bytes.
*
* @return The data for this output stream, or null if no such data is available.
*/
public byte[] getData() {
return memoryOutputStream.toByteArray();
}
/**
* Closes underlying output stream, and mark this as closed
*
* @exception IOException if an error occurs.
*/
@Override
public void close() throws IOException {
super.close();
closed = true;
}
/**
* Writes the data from this output stream to the specified output stream, after it has been
* closed.
*
* @param out output stream to write to.
* @exception IOException if this stream is not yet closed or an error occurs.
*/
public void writeTo(OutputStream out) throws IOException {
// we may only need to check if this is closed if we are working with a
// file
// but we should force the habit of closing wether we are working with
// a file or memory.
if (!closed) {
throw new IOException("Stream not closed");
}
memoryOutputStream.writeTo(out);
}
}