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/*
* 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;
import java.io.FileInputStream;
import java.security.DigestInputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.util.Locale;
import org.apache.tools.ant.BuildException;
/**
* Computes a 'hashvalue' for the content of file using
* java.security.MessageDigest.
* 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> MD5 | SHA (default provider) </td>
* <td> name of the algorithm the provider should use </td>
* <td> no, defaults to MD5 </td>
* </tr>
* <tr>
* <td> algorithm.provider </td>
* <td> </td>
* <td> name of the provider to use </td>
* <td> no, defaults to <i>null</i> </td>
* </tr>
* </table>
*
* @version 2004-07-08
* @since Ant 1.6
*/
public class DigestAlgorithm implements Algorithm {
private static final int BYTE_MASK = 0xFF;
private static final int BUFFER_SIZE = 8192;
// ----- member variables -----
/**
* MessageDigest algorithm to be used.
*/
private String algorithm = "MD5";
/**
* MessageDigest Algorithm provider
*/
private String provider = null;
/**
* Message Digest instance
*/
private MessageDigest messageDigest = null;
/**
* Size of the read buffer to use.
*/
private int readBufferSize = BUFFER_SIZE;
// ----- Algorithm-Configuration -----
/**
* Specifies the algorithm to be used to compute the checksum.
* Defaults to "MD5". Other popular algorithms like "SHA" 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;
}
/**
* Sets the MessageDigest algorithm provider to be used
* to calculate the checksum.
* @param provider provider to use
*/
public void setProvider(String provider) {
this.provider = provider;
}
/** Initialize the security message digest. */
public void initMessageDigest() {
if (messageDigest != null) {
return;
}
if ((provider != null) && !"".equals(provider) && !"null".equals(provider)) {
try {
messageDigest = MessageDigest.getInstance(algorithm, provider);
} catch (NoSuchAlgorithmException noalgo) {
throw new BuildException(noalgo);
} catch (NoSuchProviderException noprovider) {
throw new BuildException(noprovider);
}
} else {
try {
messageDigest = MessageDigest.getInstance(algorithm);
} catch (NoSuchAlgorithmException noalgo) {
throw new BuildException(noalgo);
}
}
}
// ----- Logic -----
/**
* This algorithm supports only MD5 and SHA.
* @return <i>true</i> if all is ok, otherwise <i>false</i>.
*/
public boolean isValid() {
return "SHA".equals(algorithm) || "MD5".equals(algorithm);
}
/**
* Computes a value for a file content with the specified digest algorithm.
* @param file File object for which the value should be evaluated.
* @return The value for that file
*/
// implementation adapted from ...taskdefs.Checksum, thanks to Magesh for hint
public String getValue(File file) {
initMessageDigest();
String checksum = null;
try {
if (!file.canRead()) {
return null;
}
FileInputStream fis = null;
byte[] buf = new byte[readBufferSize];
try {
messageDigest.reset();
fis = new FileInputStream(file);
DigestInputStream dis = new DigestInputStream(fis,
messageDigest);
while (dis.read(buf, 0, readBufferSize) != -1) {
// do nothing
}
dis.close();
fis.close();
fis = null;
byte[] fileDigest = messageDigest.digest();
StringBuffer checksumSb = new StringBuffer();
for (int i = 0; i < fileDigest.length; i++) {
String hexStr
= Integer.toHexString(BYTE_MASK & fileDigest[i]);
if (hexStr.length() < 2) {
checksumSb.append("0");
}
checksumSb.append(hexStr);
}
checksum = checksumSb.toString();
} catch (Exception e) {
return null;
}
} catch (Exception e) {
return null;
}
return checksum;
}
/**
* Override Object.toString().
* @return some information about this algorithm.
*/
public String toString() {
StringBuilder buf = new StringBuilder();
buf.append("<DigestAlgorithm:");
buf.append("algorithm=").append(algorithm);
buf.append(";provider=").append(provider);
buf.append(">");
return buf.toString();
}
}
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