au.com.acegi.xmlformat.IOUtil Maven / Gradle / Ivy
/*-
* #%L
* XML Format Maven Plugin
* %%
* Copyright (C) 2011 - 2017 Acegi Technology Pty Limited
* %%
* Licensed 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.
* #L%
*/
package au.com.acegi.xmlformat;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.zip.CRC32;
import java.util.zip.CheckedInputStream;
import java.util.zip.Checksum;
/**
* Utility methods for dealing with I/O resources.
*/
final class IOUtil {
private IOUtil() {
}
/**
* Returns a CRC32 of the provided input stream.
*
* @param in to CRC32
* @return the CRC32 value
* @throws IOException if unable to read the input stream
*/
static long hash(final InputStream in) throws IOException {
final Checksum cksum = new CRC32();
final CheckedInputStream is = new CheckedInputStream(in, cksum);
final byte[] buff = new byte[4_096];
while (is.read(buff) >= 0) {
// CheckInputStream will update its internal checksum
}
return is.getChecksum().getValue();
}
/**
* Returns a CRC32 of the given file.
*
* @param file to CRC32
* @return the CRC32 value
* @throws IOException if unable to read the file
*/
static long hash(final File file) throws IOException {
try (FileInputStream fis = new FileInputStream(file);) {
return hash(fis);
}
}
}