cziegeler 2003/02/07 03:21:00
Added: sourceresolve/src/java/org/apache/excalibur/source/impl
FileSource.java
Log:
Adding FileSource from cocoon
Revision Changes Path
1.1
avalon-excalibur/sourceresolve/src/java/org/apache/excalibur/source/impl/FileSource.java
Index: FileSource.java
===================================================================
/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2002 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software
* itself, if and wherever such third-party acknowledgments
* normally appear.
*
* 4. The names "Jakarta", "Avalon", and "Apache Software Foundation"
* must not be used to endorse or promote products derived from this
* software without prior written permission. For written
* permission, please contact [EMAIL PROTECTED]
*
* 5. Products derived from this software may not be called "Apache",
* nor may "Apache" appear in their name, without prior written
* permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*/
package org.apache.excalibur.source.impl;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URL;
import java.util.ConcurrentModificationException;
import java.util.Map;
import org.apache.excalibur.source.ModifiableSource;
import org.apache.excalibur.source.SourceException;
import org.apache.excalibur.source.impl.URLSource;
/**
* A {@link ModifiableSource} for 'file:/' system IDs.
*
* @author <a href="mailto:[EMAIL PROTECTED]";>Sylvain Wallez</a>
* @version $Id: FileSource.java,v 1.1 2003/02/07 11:21:00 cziegeler Exp $
*/
public class FileSource
extends URLSource
implements ModifiableSource {
/**
* Initialize a new object from a <code>URL</code>.
* @param parameters This is optional
*/
public void init(URL url,
Map parameters )
throws IOException {
super.init( url, parameters );
if ( null == this.file ) {
throw new IllegalArgumentException("Malformed url for a file source : "
+ url);
}
}
/**
* Get the associated file
*/
public File getFile() {
return this.file;
}
/**
* A file outputStream that will rename the temp file to the destination file
upon close()
* and discard the temp file upon cancel().
*/
private class FileSourceOutputStream extends FileOutputStream {
private File tmpFile;
private boolean isClosed = false;
private FileSource source;
public FileSourceOutputStream(File tmpFile, FileSource source) throws
IOException {
super(tmpFile);
this.tmpFile = tmpFile;
this.source = source;
}
public void close() throws IOException {
if (!this.isClosed) {
super.close();
try {
// Delete destination file
if (this.source.getFile().exists()) {
this.source.getFile().delete();
}
// Rename temp file to destination file
tmpFile.renameTo(this.source.getFile());
} finally {
// Ensure temp file is deleted, ie lock is released.
// If there was a failure above, written data is lost.
if (tmpFile.exists()) {
tmpFile.delete();
}
this.isClosed = true;
}
}
}
public boolean canCancel() {
return !this.isClosed;
}
public void cancel() throws Exception {
if (this.isClosed) {
throw new IllegalStateException("Cannot cancel : outputstrem is
already closed");
}
this.isClosed = true;
super.close();
this.tmpFile.delete();
}
public void finalize() {
if (!this.isClosed && tmpFile.exists()) {
// Something wrong happened while writing : delete temp file
tmpFile.delete();
}
}
public FileSource getSource() {
return this.source;
}
}
/**
* Does this source actually exist ?
*
* @return true if the resource exists.
*/
public boolean exists() {
return this.file.exists();
}
/**
* Get an <code>InputStream</code> where raw bytes can be written to.
* The signification of these bytes is implementation-dependent and
* is not restricted to a serialized XML document.
*
* Get an output stream to write to this source. The output stream returned
* actually writes to a temp file that replaces the real one on close. This
* temp file is used as lock to forbid multiple simultaneous writes. The
* real file is updated atomically when the output stream is closed.
*
* @return a stream to write to
* @throws ConcurrentModificationException if another thread is currently
* writing to this file.
*/
public OutputStream getOutputStream()
throws IOException, SourceException {
// Create a temp file. It will replace the right one when writing terminates,
// and serve as a lock to prevent concurrent writes.
File tmpFile = new File(this.file.getPath() + ".tmp");
// Ensure the directory exists
tmpFile.getParentFile().mkdirs();
// Can we write the file ?
if (this.file.exists() && !this.file.canWrite()) {
throw new IOException("Cannot write to file " + this.file.getPath());
}
// Check if it temp file already exists, meaning someone else currently
writing
if (!tmpFile.createNewFile()) {
throw new ConcurrentModificationException("File " + this.file.getPath() +
" is already being written by another thread");
}
// Return a stream that will rename the temp file on close.
return new FileSourceOutputStream(tmpFile, this);
}
/**
* Can the data sent to an <code>OutputStream</code> returned by
* {@link #getOutputStream()} be cancelled ?
*
* @return true if the stream can be cancelled
*/
public boolean canCancel(OutputStream stream) {
if (stream instanceof FileSourceOutputStream) {
FileSourceOutputStream fsos = (FileSourceOutputStream)stream;
if (fsos.getSource() == this) {
return fsos.canCancel();
}
}
// Not a valid stream for this source
throw new IllegalArgumentException("The stream is not associated to this
source");
}
/**
* Cancel the data sent to an <code>OutputStream</code> returned by
* {@link #getOutputStream()}.
* <p>
* After cancel, the stream should no more be used.
*/
public void cancel(OutputStream stream) throws SourceException {
if (stream instanceof FileSourceOutputStream) {
FileSourceOutputStream fsos = (FileSourceOutputStream)stream;
if (fsos.getSource() == this) {
try {
fsos.cancel();
} catch (Exception e) {
throw new SourceException("Exception during cancel.", e);
}
return;
}
}
// Not a valid stream for this source
throw new IllegalArgumentException("The stream is not associated to this
source");
}
/**
* Delete the source.
*/
public boolean delete() {
return this.file.delete();
}
}
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