org.apache.tools.ant.types.selectors.modifiedselector.ChecksumAlgorithm Maven / Gradle / Ivy
/*
* 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
*
* https://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.BufferedInputStream;
import java.io.File;
import java.nio.file.Files;
import java.security.NoSuchAlgorithmException;
import java.util.Locale;
import java.util.zip.Adler32;
import java.util.zip.CRC32;
import java.util.zip.CheckedInputStream;
import java.util.zip.Checksum;
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:
*
* Checksum algorithm parameters
*
* name values description required
*
*
* algorithm.algorithm
* ADLER | CRC (default)
* name of the algorithm the checksum should use
* no, defaults to CRC
*
*
*
* @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 != null ? algorithm.toUpperCase(Locale.ENGLISH) : null;
}
/** Initialize the checksum interface. */
public void initChecksum() {
if (checksum != null) {
return;
}
if ("CRC".equals(algorithm)) {
checksum = new CRC32();
} else if ("ADLER".equals(algorithm)) {
checksum = new Adler32();
} else {
throw new BuildException(new NoSuchAlgorithmException());
}
}
// ----- Logic -----
/**
* This algorithm supports only CRC and Adler.
* @return true if all is ok, otherwise false.
*/
@Override
public boolean isValid() {
return "CRC".equals(algorithm) || "ADLER".equals(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
*/
@Override
public String getValue(File file) {
initChecksum();
if (file.canRead()) {
checksum.reset();
try (CheckedInputStream check = new CheckedInputStream(
new BufferedInputStream(Files.newInputStream(file.toPath())), checksum)) {
// Read the file
while (check.read() != -1) {
}
return Long.toString(check.getChecksum().getValue());
} catch (Exception ignored) {
}
}
return null;
}
/**
* Override Object.toString().
* @return some information about this algorithm.
*/
@Override
public String toString() {
return String.format("", algorithm);
}
}