001/**
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.fs;
019
020import java.util.Arrays;
021
022import org.apache.hadoop.classification.InterfaceAudience;
023import org.apache.hadoop.classification.InterfaceStability;
024import org.apache.hadoop.io.Writable;
025
026/** An abstract class representing file checksums for files. */
027@InterfaceAudience.Public
028@InterfaceStability.Stable
029public abstract class FileChecksum implements Writable {
030  /** The checksum algorithm name */ 
031  public abstract String getAlgorithmName();
032
033  /** The length of the checksum in bytes */ 
034  public abstract int getLength();
035
036  /** The value of the checksum in bytes */ 
037  public abstract byte[] getBytes();
038
039  /** Return true if both the algorithms and the values are the same. */
040  public boolean equals(Object other) {
041    if (other == this) {
042      return true;
043    }
044    if (other == null || !(other instanceof FileChecksum)) {
045      return false;
046    }
047
048    final FileChecksum that = (FileChecksum)other;
049    return this.getAlgorithmName().equals(that.getAlgorithmName())
050      && Arrays.equals(this.getBytes(), that.getBytes());
051  }
052  
053  /** {@inheritDoc} */
054  public int hashCode() {
055    return getAlgorithmName().hashCode() ^ Arrays.hashCode(getBytes());
056  }
057}