| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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.apache.tools.ant.types.selectors.modifiedselector; |
| |
| |
| import java.io.File; |
| |
| |
| /** |
| * Computes a 'hashvalue' for the content of file using String.hashValue(). |
| * Use of this algorithm doesn't require any additional nested <param>s and |
| * doesn't support any. |
| * |
| * @version 2003-09-13 |
| * @since Ant 1.6 |
| */ |
| public class HashvalueAlgorithm implements Algorithm { |
| |
| /** |
| * This algorithm doesn't need any configuration. |
| * Therefore it's always valid. |
| * @return always true |
| */ |
| public boolean isValid() { |
| return true; |
| } |
| |
| /** |
| * Computes a 'hashvalue' for a file content. |
| * It reads the content of a file, convert that to String and use the |
| * String.hashCode() method. |
| * @param file The file for which the value should be computed |
| * @return the hashvalue or <i>null</i> if the file couldn't be read |
| */ |
| // Because the content is only read the file will not be damaged. I tested |
| // with JPG, ZIP and PDF as binary files. |
| public String getValue(File file) { |
| try { |
| if (!file.canRead()) { |
| return null; |
| } |
| java.io.FileInputStream fis = new java.io.FileInputStream(file); |
| byte[] content = new byte[fis.available()]; |
| fis.read(content); |
| fis.close(); |
| String s = new String(content); |
| int hash = s.hashCode(); |
| return Integer.toString(hash); |
| } catch (Exception e) { |
| return null; |
| } |
| } |
| |
| |
| /** |
| * Override Object.toString(). |
| * @return information about this comparator |
| */ |
| public String toString() { |
| return "HashvalueAlgorithm"; |
| } |
| |
| } |