ratpack.file.checksummer.internal.MD5Checksummer Maven / Gradle / Ivy
/*
* Copyright 2014 the original author or authors.
*
* 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.
*/
package ratpack.file.checksummer.internal;
import java.io.InputStream;
import ratpack.func.Function;
import java.security.MessageDigest;
/**
* Calculate checksum with MD5 algorithm.
*
* This function type is implementation of {@link ratpack.func.Function} interface and
* takes {@code InputStream} as parameter while returns {@code String} with calculated checksum.
*/
public class MD5Checksummer implements Function {
private static final int BUFFER_SIZE = 8192;
/**
* Algorythm implementation.
*
* @param is {@code InputStream} of file to calculate checksum
* @return checksum string
*/
@Override
public String apply(InputStream is) throws Exception {
byte[] buffer = new byte[BUFFER_SIZE];
MessageDigest md = MessageDigest.getInstance("MD5");
int read = is.read(buffer, 0, BUFFER_SIZE);
while (read != -1) {
md.update(buffer, 0, read);
read = is.read(buffer, 0, BUFFER_SIZE);
}
byte[] digest = md.digest();
StringBuilder sb = new StringBuilder();
for (int i=0; i < digest.length; i++) {
sb.append(Integer.toString((digest[i] & 0xFF) + 0x100, 16).substring(1));
}
return sb.toString();
}
}