/**
* The contents of this file are subject to the license and copyright
* detailed in the LICENSE and NOTICE files at the root of the source
* tree and available online at
*
* http://www.dspace.org/license/
*/
package org.purl.sword.base;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import org.apache.log4j.Logger;
/**
* Utility class that holds Checksum related methods.
*
* @author Neil Taylor
* @author Stuart Lewis
*/
public class ChecksumUtils
{
/** Logger */
private static Logger log = Logger.getLogger(ChecksumUtils.class);
/**
* Generate an MD5 hash for the file that is specified in the
* filepath. The hash is returned as a String representation.
*
* @param filepath The path to the file to load.
* @return A string hash of the file.
* @throws NoSuchAlgorithmException If the MD5 algorithm is
* not supported by the installed virtual machine.
*
* @throws IOException If there is an error accessing the file.
*/
public static String generateMD5(String filepath)
throws NoSuchAlgorithmException, IOException
{
return generateMD5(new FileInputStream(filepath));
}
/**
* Generate an MD5 hash for the file that is specified in the
* filepath. The hash is returned as a String representation.
*
* @param md5Stream The InputStream to checksum.
* @return A string hash of the file.
* @throws NoSuchAlgorithmException If the MD5 algorithm is
* not supported by the installed virtual machine.
*
* @throws IOException If there is an error accessing the file.
*/
public static String generateMD5(InputStream md5Stream)
throws NoSuchAlgorithmException, IOException
{
String md5 = null;
try
{
MessageDigest md = MessageDigest.getInstance("MD5");
md.reset();
byte[] bytes = new byte[1024];
int count = 0;
while ( (count = md5Stream.read(bytes)) != -1 )
{
md.update(bytes, 0, count);
}
byte[] md5Digest = md.digest();
StringBuffer buffer = new StringBuffer();
for ( byte b : md5Digest )
{
// 0xFF is used to handle the issue of negative numbers in the bytes
String hex = Integer.toHexString(b & 0xFF);
if ( hex.length() == 1 )
{
buffer.append("0");
}
buffer.append(hex);
}
md5 = buffer.toString();
}
catch (NoSuchAlgorithmException ex )
{
log.error("MD5 Algorithm Not found");
throw ex;
}
finally
{
if ( md5Stream != null )
{
md5Stream.close();
}
}
return md5;
}
/**
* Generate an MD5 hash for the file that is specified in the
* filepath. The hash is returned as a String representation.
*
* @param bytes The byte array to checksum.
* @return A string hash of the file.
* @throws NoSuchAlgorithmException If the MD5 algorithm is
* not supported by the installed virtual machine.
*
* @throws IOException If there is an error accessing the file.
*/
public static String generateMD5(byte[] bytes)
throws NoSuchAlgorithmException, IOException
{
String md5 = null;
try
{
MessageDigest md = MessageDigest.getInstance("MD5");
md.reset();
md.update(bytes);
byte[] md5Digest = md.digest();
StringBuffer buffer = new StringBuffer();
for ( byte b : md5Digest )
{
// 0xFF is used to handle the issue of negative numbers in the bytes
String hex = Integer.toHexString(b & 0xFF);
if ( hex.length() == 1 )
{
buffer.append("0");
}
buffer.append(hex);
}
md5 = buffer.toString();
}
catch (NoSuchAlgorithmException ex)
{
log.error("MD5 Algorithm Not found");
throw ex; // rethrow
}
return md5;
}
/**
* Run a simple test to process the file.
*
* @param args the command line arguments given
* @throws NoSuchAlgorithmException If there was an error generating the MD5.
* @throws IOException If there is an error accessing the file.
*/
public static void main(String[] args)
throws NoSuchAlgorithmException, IOException
{
System.out.println(ChecksumUtils.generateMD5(args[0]));
}
}