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/*
* Copyright 2005 The Apache Software Foundation
*
* Licensed 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.osgi.moduleloader;
import java.io.*;
import java.util.jar.JarFile;
import java.util.zip.ZipEntry;
/**
* <p>
* This class implements a <tt>ResourceSource</tt> for retrieving resources
* from a JAR file. The approach used by this implementation is to defer
* opening the JAR file until a request for a resource is made.
* </p>
* @see org.apache.osgi.moduleloader.ResourceSource
**/
public class JarResourceSource implements ResourceSource
{
private static final int BUFSIZE = 4096;
private File m_file = null;
private JarFile m_jarFile = null;
private boolean m_opened = false;
/**
* <p>
* Constructs an instance using the specified file name as the source
* of the JAR file.
* </p>
* @param fileName the name of the JAR file to be used as the source.
**/
public JarResourceSource(String fileName)
{
m_file = new File(fileName);
}
/**
* <p>
* Constructs an instance using the specified file as the source
* of the JAR file.
* </p>
* @param file the JAR file to be used as the source.
**/
public JarResourceSource(File file)
{
m_file = file;
}
/**
* <p>
* Closes the JAR file if it has not already been closed.
* <p>
**/
protected void finalize()
{
if (m_jarFile != null)
{
try {
m_jarFile.close();
} catch (IOException ex) {
// Not much we can do, so ignore it.
}
}
}
/**
* <p>
* This method initializes the resource source. Since opening
* the JAR file is deferred until a request for a resource is
* actually made, this method really only sets a flag indicating
* that the resource source has been initialized.
* <p>
**/
public void open()
{
m_opened = true;
}
/**
* <p>
* This method deinitializes the resource source by closing
* the associated JAR file if it is open.
* <p>
**/
public synchronized void close()
{
try {
if (m_jarFile != null)
{
m_jarFile.close();
}
} catch (Exception ex) {
System.err.println("JarResourceSource: " + ex);
}
m_jarFile = null;
m_opened = false;
}
// JavaDoc comments are copied from ResourceSource.
public synchronized boolean hasResource(String name) throws IllegalStateException
{
if (!m_opened)
{
throw new IllegalStateException("JarResourceSource is not open");
}
// Open JAR file if not already opened.
if (m_jarFile == null)
{
try {
openJarFile();
} catch (IOException ex) {
System.err.println("JarResourceSource: " + ex);
return false;
}
}
try {
ZipEntry ze = m_jarFile.getEntry(name);
return ze != null;
} catch (Exception ex) {
return false;
} finally {
}
}
// JavaDoc comments are copied from ResourceSource.
public synchronized byte[] getBytes(String name) throws IllegalStateException
{
if (!m_opened)
{
throw new IllegalStateException("JarResourceSource is not open");
}
// Open JAR file if not already opened.
if (m_jarFile == null)
{
try {
openJarFile();
} catch (IOException ex) {
System.err.println("JarResourceSource: " + ex);
return null;
}
}
// Get the embedded resource.
InputStream is = null;
ByteArrayOutputStream baos = null;
try {
ZipEntry ze = m_jarFile.getEntry(name);
if (ze == null)
{
return null;
}
is = m_jarFile.getInputStream(ze);
if (is == null)
{
return null;
}
baos = new ByteArrayOutputStream(BUFSIZE);
byte[] buf = new byte[BUFSIZE];
int n = 0;
while ((n = is.read(buf, 0, buf.length)) >= 0)
{
baos.write(buf, 0, n);
}
return baos.toByteArray();
} catch (Exception ex) {
return null;
} finally {
try {
if (baos != null) baos.close();
} catch (Exception ex) {
}
try {
if (is != null) is.close();
} catch (Exception ex) {
}
}
}
private void openJarFile() throws IOException
{
if (m_jarFile == null)
{
m_jarFile = new JarFile(m_file);
}
}
public String toString()
{
return "JAR " + m_file.getPath();
}
}