/*
* Copyright 2002-2015 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 org.springframework.util;
import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
/**
* Extension of {@link java.io.InputStream} that allows for optimized
* implementations of message digesting.
*
* @author Craig Andrews
* @since 4.2
*/
abstract class UpdateMessageDigestInputStream extends InputStream {
/**
* Update the message digest with the rest of the bytes in this stream.
* <p>Using this method is more optimized since it avoids creating new
* byte arrays for each call.
* @param messageDigest the message digest to update
* @throws IOException when propagated from {@link #read()}
*/
public void updateMessageDigest(MessageDigest messageDigest) throws IOException {
int data;
while ((data = read()) != -1){
messageDigest.update((byte) data);
}
}
/**
* Update the message digest with the next len bytes in this stream.
* <p>Using this method is more optimized since it avoids creating new
* byte arrays for each call.
* @param messageDigest the message digest to update
* @param len how many bytes to read from this stream and use to update the message digest
* @throws IOException when propagated from {@link #read()}
*/
public void updateMessageDigest(MessageDigest messageDigest, int len) throws IOException {
int data;
int bytesRead = 0;
while (bytesRead < len && (data = read()) != -1){
messageDigest.update((byte) data);
bytesRead++;
}
}
}