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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.vfs2.util;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.commons.vfs2.FileSystemException;
/**
* An OutputStream that provides buffering and end-of-stream monitoring.
*/
public class MonitorOutputStream extends BufferedOutputStream {
private final AtomicBoolean finished = new AtomicBoolean(false);
public MonitorOutputStream(final OutputStream out) {
super(out);
}
/**
* Closes this output stream.
*
* This makes sure the buffers are flushed, close the output stream and it will call {@link #onClose()} and re-throw
* last exception from any of the three.
*
* This does nothing if the stream is closed already.
*
* @throws IOException if an error occurs.
*/
@Override
public void close() throws IOException {
// do not use super.close()
// on Java 8 it might throw self suppression, see JDK-8042377
// in older Java it silently ignores flush() errors
if (finished.getAndSet(true)) {
return;
}
IOException exc = null;
// flush the buffer and out stream
try {
super.flush();
} catch (final IOException ioe) {
exc = ioe;
}
// close the out stream without using super.close()
try {
super.out.close();
} catch (final IOException ioe) {
exc = ioe;
}
// Notify of end of output
try {
onClose();
} catch (final IOException ioe) {
exc = ioe;
}
if (exc != null) {
throw exc;
}
}
/**
* @param b The character to write.
* @throws IOException if an error occurs.
* @since 2.0
*/
@Override
public synchronized void write(final int b) throws IOException {
assertOpen();
super.write(b);
}
/**
* @param b The byte array.
* @param off The offset into the array.
* @param len The number of bytes to write.
* @throws IOException if an error occurs.
* @since 2.0
*/
@Override
public synchronized void write(final byte[] b, final int off, final int len) throws IOException {
assertOpen();
super.write(b, off, len);
}
/**
* @throws IOException if an error occurs.
* @since 2.0
*/
@Override
public synchronized void flush() throws IOException {
assertOpen();
super.flush();
}
/**
* @param b The byte array.
* @throws IOException if an error occurs.
* @since 2.0
*/
@Override
public void write(final byte[] b) throws IOException {
assertOpen();
super.write(b);
}
/**
* Check if file is still open.
*
* This is a workaround for an oddity with Java's BufferedOutputStream where you can write to even if the stream has
* been closed.
*
* @throws FileSystemException if already closed.
* @since 2.0
*/
protected void assertOpen() throws FileSystemException {
if (finished.get()) {
throw new FileSystemException("vfs.provider/closed.error");
}
}
/**
* Called after this stream is closed.
*
* This implementation does nothing.
*
* @throws IOException if an error occurs.
*/
// IOException is needed because subclasses may need to throw it
protected void onClose() throws IOException {
}
}