/**
* Copyright 2010 JBoss Inc
*
* 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.eclipse.webdav.internal.authentication;
import java.io.*;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
/**
* <P>An <code>OutputStream</code> that filters its data through a
* <code>MessageDigest</code> to compute a hash value over the data.
*/
public class DigestOutputStream extends FilterOutputStream {
private static class NullOutputStream extends OutputStream {
public void write(int b) throws IOException {
// do nothing
}
}
private MessageDigest messageDigest = null;
private byte[] digest = null;
/**
* Creates a new <code>DigestOutputStream</code> that filters its data
* through a <code>MessageDigest</code> that hashes its input using the
* given algorithm.
*
* @param out the data is also written to the given output stream
* @param algorithm a hashing algorithm, for example: "MD5"
*/
public DigestOutputStream(OutputStream out, String algorithm) throws NoSuchAlgorithmException {
super(out);
messageDigest = MessageDigest.getInstance(algorithm);
}
/**
* Creates a new <code>DigestOutputStream</code> that filters its data
* through a <code>MessageDigest</code> that hashes its input using the
* given algorithm.
*
* @param algorithm a hashing algorithm, for example: "MD5"
*/
public DigestOutputStream(String algorithm) throws NoSuchAlgorithmException {
this(new NullOutputStream(), algorithm);
}
/**
* Completes the hash computation and resets the digest.
*
* @returns the hash value
*/
public byte[] digest() {
if (digest == null)
digest = messageDigest.digest();
return digest;
}
/**
* @see OutputStream#write(byte[], int, int)
*/
public void write(byte b[], int off, int len) throws IOException {
out.write(b, off, len);
messageDigest.update(b, off, len);
}
/**
* @see OutputStream#write(int)
*/
public void write(int b) throws IOException {
out.write(b);
messageDigest.update((byte) b);
}
}