| /* |
| * 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.util.zip.Checksum; |
| import java.util.zip.CRC32; |
| import java.util.zip.Adler32; |
| import java.util.zip.CheckedInputStream; |
| import java.io.File; |
| import java.io.FileInputStream; |
| import java.io.BufferedInputStream; |
| import java.security.NoSuchAlgorithmException; |
| import org.apache.tools.ant.BuildException; |
| |
| |
| /** |
| * Computes a 'checksum' for the content of file using |
| * java.util.zip.CRC32 and java.util.zip.Adler32. |
| * Use of this algorithm doesn't require any additional nested <param>s. |
| * Supported <param>s are: |
| * <table> |
| * <tr> |
| * <th>name</th><th>values</th><th>description</th><th>required</th> |
| * </tr> |
| * <tr> |
| * <td> algorithm.algorithm </td> |
| * <td> ADLER | CRC ( default ) </td> |
| * <td> name of the algorithm the checksum should use </td> |
| * <td> no, defaults to CRC </td> |
| * </tr> |
| * </table> |
| * |
| * @version 2004-06-17 |
| * @since Ant 1.7 |
| */ |
| public class ChecksumAlgorithm implements Algorithm { |
| |
| |
| // ----- member variables ----- |
| |
| |
| /** |
| * Checksum algorithm to be used. |
| */ |
| private String algorithm = "CRC"; |
| |
| /** |
| * Checksum interface instance |
| */ |
| private Checksum checksum = null; |
| |
| |
| // ----- Algorithm-Configuration ----- |
| |
| |
| /** |
| * Specifies the algorithm to be used to compute the checksum. |
| * Defaults to "CRC". Other popular algorithms like "ADLER" may be used as well. |
| * @param algorithm the digest algorithm to use |
| */ |
| public void setAlgorithm(String algorithm) { |
| this.algorithm = algorithm; |
| } |
| |
| |
| /** Initialize the checksum interface. */ |
| public void initChecksum() { |
| if (checksum != null) { |
| return; |
| } |
| if ("CRC".equalsIgnoreCase(algorithm)) { |
| checksum = new CRC32(); |
| } else if ("ADLER".equalsIgnoreCase(algorithm)) { |
| checksum = new Adler32(); |
| } else { |
| throw new BuildException(new NoSuchAlgorithmException()); |
| } |
| } |
| |
| |
| // ----- Logic ----- |
| |
| |
| /** |
| * This algorithm supports only CRC and Adler. |
| * @return <i>true</i> if all is ok, otherwise <i>false</i>. |
| */ |
| public boolean isValid() { |
| return "CRC".equalsIgnoreCase(algorithm) || "ADLER".equalsIgnoreCase(algorithm); |
| } |
| |
| |
| /** |
| * Computes a value for a file content with the specified checksum algorithm. |
| * @param file File object for which the value should be evaluated. |
| * @return The value for that file |
| */ |
| public String getValue(File file) { |
| initChecksum(); |
| String rval = null; |
| |
| try { |
| if (file.canRead()) { |
| checksum.reset(); |
| FileInputStream fis = new FileInputStream(file); |
| CheckedInputStream check = new CheckedInputStream(fis, checksum); |
| BufferedInputStream in = new BufferedInputStream(check); |
| while (in.read() != -1) { |
| // Read the file |
| } |
| rval = Long.toString(check.getChecksum().getValue()); |
| in.close(); |
| } |
| } catch (Exception e) { |
| rval = null; |
| } |
| return rval; |
| } |
| |
| |
| /** |
| * Override Object.toString(). |
| * @return some information about this algorithm. |
| */ |
| public String toString() { |
| StringBuffer buf = new StringBuffer(); |
| buf.append("<ChecksumAlgorithm:"); |
| buf.append("algorithm=").append(algorithm); |
| buf.append(">"); |
| return buf.toString(); |
| } |
| } |