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* </tr> * <tr> * <td> algorithm.algorithm * <td> ADLER | CRC ( default ) * <td> name of the algorithm the checksum should use * <td> no, defaults to CRC * </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 if all is ok, otherwise false. */ 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(); } }

Other Ant examples (source code examples)

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Ant example source code file (ChecksumAlgorithm.java)

This example Ant source code file (ChecksumAlgorithm.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Ant tags/keywords

adler, adler, adler32, bufferedinputstream, checkedinputstream, checksumalgorithm, crc, crc, crc32, fileinputstream, fileinputstream, io, security, string, string, stringbuffer, zip

The ChecksumAlgorithm.java source code

/*
 *  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
valuesdescriptionrequired
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