Hibernate example source code file (ByteCodeHelper.java)

This example Hibernate source code file (ByteCodeHelper.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Hibernate tags/keywords

bufferedinputstream, bufferedinputstream, bytearrayoutputstream, bytearrayoutputstream, bytecodehelper, bytecodehelper, fileinputstream, inputstream, io, ioexception, ioexception, zip

The Hibernate ByteCodeHelper.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2010, Red Hat Inc. or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.bytecode.spi;

import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.zip.ZipInputStream;

/**
 * A helper for reading byte code from various input sources.
 *
 * @author Steve Ebersole
 */
public class ByteCodeHelper {
	private ByteCodeHelper() {
	}

	/**
	 * Reads class byte array info from the given input stream.
	 * <p/>
	 * The stream is closed within this method!
	 *
	 * @param inputStream The stream containing the class binary; null will lead to an {@link IOException}
	 *
	 * @return The read bytes
	 *
	 * @throws IOException Indicates a problem accessing the given stream.
	 */
	public static byte[] readByteCode(InputStream inputStream) throws IOException {
		if ( inputStream == null ) {
			throw new IOException( "null input stream" );
		}

		byte[] buffer = new byte[409600];
		byte[] classBytes = new byte[0];

		try {
			int r = inputStream.read( buffer );
			while ( r >= buffer.length ) {
				byte[] temp = new byte[ classBytes.length + buffer.length ];
				// copy any previously read bytes into the temp array
				System.arraycopy( classBytes, 0, temp, 0, classBytes.length );
				// copy the just read bytes into the temp array (after the previously read)
				System.arraycopy( buffer, 0, temp, classBytes.length, buffer.length );
				classBytes = temp;
				// read the next set of bytes into buffer
				r = inputStream.read( buffer );
			}
			if ( r != -1 ) {
				byte[] temp = new byte[ classBytes.length + r ];
				// copy any previously read bytes into the temp array
				System.arraycopy( classBytes, 0, temp, 0, classBytes.length );
				// copy the just read bytes into the temp array (after the previously read)
				System.arraycopy( buffer, 0, temp, classBytes.length, r );
				classBytes = temp;
			}
		}
		finally {
			try {
				inputStream.close();
			}
			catch (IOException ignore) {
				// intentionally empty
			}
		}

		return classBytes;
	}

	/**
	 * Read class definition from a file.
	 *
	 * @param file The file to read.
	 *
	 * @return The class bytes
	 *
	 * @throws IOException Indicates a problem accessing the given stream.
	 */
	public static byte[] readByteCode(File file) throws IOException {
		return ByteCodeHelper.readByteCode( new FileInputStream( file ) );
	}

	/**
	 * Read class definition a zip (jar) file entry.
	 *
	 * @param zip The zip entry stream.
	 * 
	 * @return The class bytes
	 *
	 * @throws IOException Indicates a problem accessing the given stream.
	 */
	public static byte[] readByteCode(ZipInputStream zip) throws IOException {
        ByteArrayOutputStream bout = new ByteArrayOutputStream();
        InputStream in = new BufferedInputStream( zip );
        int b;
        while ( ( b = in.read() ) != -1 ) {
            bout.write( b );
        }
        return bout.toByteArray();
    }
}