Java tutorial
/* * Sonatype Nexus (TM) Open Source Version * Copyright (c) 2008-present Sonatype, Inc. * All rights reserved. Includes the third-party code listed at http://links.sonatype.com/products/nexus/oss/attributions. * * This program and the accompanying materials are made available under the terms of the Eclipse Public License Version 1.0, * which accompanies this distribution and is available at http://www.eclipse.org/legal/epl-v10.html. * * Sonatype Nexus (TM) Professional Version is available from Sonatype, Inc. "Sonatype" and "Sonatype Nexus" are trademarks * of Sonatype, Inc. Apache Maven is a trademark of the Apache Software Foundation. M2eclipse is a trademark of the * Eclipse Foundation. All other trademarks are the property of their respective owners. */ package org.sonatype.nexus.blobstore.file.internal; import java.io.FilterInputStream; import java.io.InputStream; import java.security.DigestInputStream; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import org.sonatype.nexus.blobstore.file.FileOperations.StreamMetrics; import com.google.common.base.Throwables; import com.google.common.io.BaseEncoding; import com.google.common.io.CountingInputStream; /** * A utility to collect metrics about the content of an input stream. * * @since 3.0 */ public class MetricsInputStream extends FilterInputStream { private final MessageDigest messageDigest; private final CountingInputStream countingInputStream; public MetricsInputStream(final InputStream input) { this(new CountingInputStream(input), createSha1()); } private MetricsInputStream(final CountingInputStream countingStream, final MessageDigest messageDigest) { super(new DigestInputStream(countingStream, messageDigest)); this.messageDigest = messageDigest; this.countingInputStream = countingStream; } private static final BaseEncoding HEX = BaseEncoding.base16().lowerCase(); public String getMessageDigest() { return HEX.encode(messageDigest.digest()); } public long getSize() { return countingInputStream.getCount(); } public StreamMetrics getMetrics() { return new StreamMetrics(getSize(), getMessageDigest()); } private static MessageDigest createSha1() { try { return MessageDigest.getInstance("SHA1"); } catch (NoSuchAlgorithmException e) { // should never happen throw Throwables.propagate(e); } } }