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Hibernate example source code file (DataHelper.java)

This example Hibernate source code file (DataHelper.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

binarystream, bytearrayoutputstream, bytearrayoutputstream, coremessagelogger, hibernateexception, hibernateexception, io, ioexception, ioexception, log, object, string, stringbuilder, stringbuilder, unable

The Hibernate DataHelper.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.type.descriptor.java;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.Reader;
import java.io.StringReader;

import org.jboss.logging.Logger;

import org.hibernate.HibernateException;
import org.hibernate.internal.CoreMessageLogger;
import org.hibernate.internal.util.ReflectHelper;
import org.hibernate.type.descriptor.BinaryStream;

/**
 * A help for dealing with BLOB and CLOB data
 *
 * @author Steve Ebersole
 */
public class DataHelper {

    private static final CoreMessageLogger LOG = Logger.getMessageLogger(CoreMessageLogger.class, DataHelper.class.getName());

	private static Class nClobClass;
	static {
		try {
			// NClobs are only JDBC 4 (JDK 1.6) and higher
			nClobClass = ReflectHelper.classForName( "java.sql.NClob", DataHelper.class );
		}
		catch ( ClassNotFoundException e ) {
            LOG.unableToLocateNClobClass();
		}
	}

	public static boolean isNClob(Class type) {
		return nClobClass != null && nClobClass.isAssignableFrom( type );
	}

	/**
	 * Extract the contents of the given reader/stream as a string.
	 *
	 * @param reader The reader for the content
	 *
	 * @return The content as string
	 */
	public static String extractString(Reader reader) {
		// read the Reader contents into a buffer and return the complete string
		final StringBuilder stringBuilder = new StringBuilder();
		try {
			char[] buffer = new char[2048];
			while (true) {
				int amountRead = reader.read( buffer, 0, buffer.length );
				if ( amountRead == -1 ) {
					break;
				}
				stringBuilder.append( buffer, 0, amountRead );
			}
		}
		catch ( IOException ioe) {
			throw new HibernateException( "IOException occurred reading text", ioe );
		}
		finally {
			try {
				reader.close();
			}
			catch (IOException e) {
                LOG.unableToCloseStream(e);
			}
		}
		return stringBuilder.toString();
	}

	/**
	 * Extracts a portion of the contents of the given reader/stream as a string.
	 *
	 * @param characterStream The reader for the content
	 * @param start The start position/offset (0-based, per general stream/reader contracts).
	 * @param length The amount to extract
	 *
	 * @return The content as string
	 */
	private static String extractString(Reader characterStream, long start, int length) {
		StringBuilder stringBuilder = new StringBuilder( length );
		try {
			long skipped = characterStream.skip( start );
			if ( skipped != start ) {
				throw new HibernateException( "Unable to skip needed bytes" );
			}
			char[] buffer = new char[2048];
			int charsRead = 0;
			while ( true ) {
				int amountRead = characterStream.read( buffer, 0, buffer.length );
				if ( amountRead == -1 ) {
					break;
				}
				stringBuilder.append( buffer, 0, amountRead );
				if ( amountRead < buffer.length ) {
					// we have read up to the end of stream
					break;
				}
				charsRead += amountRead;
				if ( charsRead >= length ) {
					break;
				}
			}
		}
		catch ( IOException ioe ) {
			throw new HibernateException( "IOException occurred reading a binary value", ioe );
		}
		return stringBuilder.toString();
	}

	/**
	 * Extract a portion of a reader, wrapping the portion in a new reader.
	 *
	 * @param characterStream The reader for the content
	 * @param start The start position/offset (0-based, per general stream/reader contracts).
	 * @param length The amount to extract
	 *
	 * @return The content portion as a reader
	 */
	public static Object subStream(Reader characterStream, long start, int length) {
		return new StringReader( extractString( characterStream, start, length ) );
	}

	/**
	 * Extract by bytes from the given stream.
	 *
	 * @param inputStream The stream of bytes.
	 *
	 * @return The contents as a {@code byte[]}
	 */
	public static byte[] extractBytes(InputStream inputStream) {
		if ( BinaryStream.class.isInstance( inputStream ) ) {
			return ( (BinaryStream ) inputStream ).getBytes();
		}

		// read the stream contents into a buffer and return the complete byte[]
		ByteArrayOutputStream outputStream = new ByteArrayOutputStream(2048);
		try {
			byte[] buffer = new byte[2048];
			while (true) {
				int amountRead = inputStream.read( buffer );
				if ( amountRead == -1 ) {
					break;
				}
				outputStream.write( buffer, 0, amountRead );
			}
		}
		catch ( IOException ioe ) {
			throw new HibernateException( "IOException occurred reading a binary value", ioe );
		}
		finally {
			try {
				inputStream.close();
			}
			catch ( IOException e ) {
                LOG.unableToCloseInputStream(e);
			}
			try {
				outputStream.close();
			}
			catch ( IOException e ) {
                LOG.unableToCloseOutputStream(e);
			}
		}
		return outputStream.toByteArray();
	}

	/**
	 * Extract a portion of the bytes from the given stream.
	 *
	 * @param inputStream The stream of bytes.
	 * @param start The start position/offset (0-based, per general stream/reader contracts).
	 * @param length The amount to extract
	 *
	 * @return The extracted bytes
	 */
	public static byte[] extractBytes(InputStream inputStream, long start, int length) {
		if ( BinaryStream.class.isInstance( inputStream ) && Integer.MAX_VALUE > start ) {
			byte[] data = ( (BinaryStream ) inputStream ).getBytes();
			int size = Math.min( length, data.length );
			byte[] result = new byte[size];
			System.arraycopy( data, (int) start, result, 0, size );
			return result;
		}

		ByteArrayOutputStream outputStream = new ByteArrayOutputStream( length );
		try {
			long skipped = inputStream.skip( start );
			if ( skipped != start ) {
				throw new HibernateException( "Unable to skip needed bytes" );
			}
			byte[] buffer = new byte[2048];
			int bytesRead = 0;
			while ( true ) {
				int amountRead = inputStream.read( buffer );
				if ( amountRead == -1 ) {
					break;
				}
				outputStream.write( buffer, 0, amountRead );
				if ( amountRead < buffer.length ) {
					// we have read up to the end of stream
					break;
				}
				bytesRead += amountRead;
				if ( bytesRead >= length ) {
					break;
				}
			}
		}
		catch ( IOException ioe ) {
			throw new HibernateException( "IOException occurred reading a binary value", ioe );
		}
		return outputStream.toByteArray();
	}

	/**
	 * Extract a portion of the bytes from the given stream., wrapping them in a new stream.
	 *
	 * @param inputStream The stream of bytes.
	 * @param start The start position/offset (0-based, per general stream/reader contracts).
	 * @param length The amount to extract
	 *
	 * @return The extracted bytes as a stream
	 */
	public static InputStream subStream(InputStream inputStream, long start, int length) {
		return new BinaryStreamImpl( extractBytes( inputStream, start, length ) );
	}
}

Other Hibernate examples (source code examples)

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