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//ByteCodeEnhancerHelper - Java Source
//***************** package ***********************************************
package com.sun.jdo.api.persistence.enhancer;
//***************** import ************************************************
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.util.zip.CRC32;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
import java.util.zip.ZipOutputStream;
//#########################################################################
/**
* This is a helper-class to perform some useful operations outside a
* byte code enhancer and delegate the real work to the enhancer.
*/
//#########################################################################
public class ByteCodeEnhancerHelper
{
/**********************************************************************
* Enhances a classfile.
*
* @param enhancer The enhancer to delegate the work to.
* @param in The input stream with the Java class.
* @param out The output stream to write the enhanced class to.
*
* @return Has the input stream been enhanced?
*
* @exception EnhancerUserException If something went wrong.
* @exception EnhancerFatalError If something went wrong.
*
* @see ByteCodeEnhancer#enhanceClassFile
*********************************************************************/
public static final boolean enhanceClassFile (ByteCodeEnhancer enhancer,
InputStream in,
OutputStream out)
throws EnhancerUserException,
EnhancerFatalError
{
return enhancer.enhanceClassFile (in, new OutputStreamWrapper (out));
} //ByteCodeEnhancerHelper.enhanceClassFile()
/**********************************************************************
* Enhances a zip file. The zip file is given as a uip input stream.
* It's entries are read and - if necessary - individually enhanced.
* The output stream has the same compression (if any) as the input
* stream.
*
* @param enhancer The enhancer.
* @param zip_in The zip input stream.
* @param zip_out The zip output stream.
*
* @param <code>true</code> if at least one entry of the zip file has
* been enhanced, <code>false</code> otherwise.
*
* @exception EnhancerUserException If something went wrong.
* @exception EnhancerFatalError If something went wrong.
*
* @see ByteCodeEnhancer#enhanceClassFile
*********************************************************************/
public static final boolean enhanceZipFile (ByteCodeEnhancer enhancer,
ZipInputStream zip_in,
ZipOutputStream zip_out)
throws EnhancerUserException,
EnhancerFatalError
{
boolean enhanced = false;
try
{
CRC32 crc32 = new CRC32 ();
ZipEntry entry;
while ((entry = zip_in.getNextEntry ()) != null)
{
InputStream in = zip_in;
ZipEntry out_entry = new ZipEntry (entry);
//try to enhance
if (isClassFileEntry (entry)) //enhance the classfile
{
//we have to copy the classfile, because if it won't be enhanced,
//the OutputStream is empty and we have to re-read the InputStream,
//which is impossiblewith a ZipInputStream (no mark/reset)
in = openZipEntry (zip_in);
in.mark (Integer.MAX_VALUE);
ByteArrayOutputStream tmp = new ByteArrayOutputStream ();
if (enhancer.enhanceClassFile (in, tmp))
{
enhanced = true;
byte [] bytes = tmp.toByteArray ();
tmp.close ();
in.close ();
modifyZipEntry (out_entry, bytes, crc32);
in = new ByteArrayInputStream (bytes);
}
else
{
//the classfile has not been enhanced
in.reset ();
}
}
//copy the entry
zip_out.putNextEntry (out_entry);
copyZipEntry (in, zip_out);
zip_out.closeEntry ();
if (in != zip_in)
{
in.close ();
}
}
}
catch (IOException ex)
{
throw new EnhancerFatalError (ex);
}
return enhanced;
} //ByteCodeEnhancerHelper.enhanceZipFile()
/**********************************************************************
* Copies a zip entry from one stream to another.
*
* @param in The inout stream.
* @param out The output stream.
*
* @exception IOException If the stream access failed.
*********************************************************************/
private static final void copyZipEntry (InputStream in,
OutputStream out)
throws IOException
{
int b;
while ((in.available () > 0) && (b = in.read ()) > -1)
{
out.write (b);
}
} //ByteCodeEnhancerHelper.copyZipEntry()
/**********************************************************************
* Opens the next zip entry of a zip input stream and copies it to
* a <code>java.io.ByteArrayOutputStream</code>. It's byte array is made
* available via an <code>java.io.ByteArrayInputStream</code> which is
* returned.
*
* @param in The zip input stream.
*
* @return The newly created input stream with the next zip entry.
*
* @exception IOException If an I/O operation failed.
*********************************************************************/
private static final InputStream openZipEntry (ZipInputStream in)
throws IOException
{
ByteArrayOutputStream out = new ByteArrayOutputStream ();
copyZipEntry (in, out);
return new ByteArrayInputStream (out.toByteArray ());
} //ByteCodeEnhancerHelper.openZipEntry()
/**********************************************************************
* Modifies the given zip entry so that it can be added to zip file.
* The given zip entry represents an enhanced class, so the zip entry
* has to get the correct size and checksum (but only it the entry won't
* be compressed).
*
* @param entry The zip entry to modify.
* @param bytes The uncompressed byte representation of the classfile.
* @param crc32 The checksum evaluator.
*********************************************************************/
private static final void modifyZipEntry (ZipEntry entry,
byte [] bytes,
CRC32 crc32)
{
entry.setSize (bytes.length);
if (entry.getMethod () == 0) //no compression (ZipInputStream.STORED - not accessible)
{
crc32.reset ();
crc32.update (bytes);
entry.setCrc (crc32.getValue ());
entry.setCompressedSize (bytes.length);
}
} //ByteCodeEnhancerHelper.modifyZipEntry()
/**********************************************************************
* Determines if a given entry represents a classfile.
*
* @return Does the given entry represent a classfile?
*********************************************************************/
private static final boolean isClassFileEntry (ZipEntry entry)
{
return entry.getName ().endsWith (".class");
} //ByteCodeEnhancerHelper.isClassFileEntry()
} //ByteCodeEnhancerHelper
//ByteCodeEnhancer - Java Source End
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