com.disney.groovity.util.HashWriter Maven / Gradle / Ivy
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* Licensed under the Apache License, Version 2.0 (the "Apache License")
* with the following modification; you may not use this file except in
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*
* 6. Trademarks. This License does not grant permission to use the trade
* names, trademarks, service marks, or product names of the Licensor
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* the License and to reproduce the content of the NOTICE file.
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*
* http://www.apache.org/licenses/LICENSE-2.0
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package com.disney.groovity.util;
import java.io.IOException;
import java.io.Writer;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CoderResult;
import java.security.MessageDigest;
/**
* HashWriter converts characters to bytes, hashes them and discards them as they are written
*
* @author Alex Vigdor
*
*/
public class HashWriter extends Writer {
final MessageDigest digest;
final CharsetEncoder encoder;
final ByteBuffer buffer;
boolean used = false;
byte[] hash;
public HashWriter(MessageDigest digest, CharsetEncoder encoder ) {
this.digest = digest;
this.encoder = encoder;
this.buffer = ByteBuffer.allocate(1024);
}
@Override
public void write(char[] cbuf, int off, int len) throws IOException {
used = true;
CharBuffer input = CharBuffer.wrap(cbuf, off, len);
CoderResult result = null;
while(result == null || result.isOverflow()) {
result = encoder.encode(input, buffer, false);
buffer.flip();
digest.update(buffer);
buffer.clear();
}
}
@Override
public void flush() throws IOException {
}
@Override
public void close() throws IOException {
encoder.encode(CharBuffer.allocate(0),buffer,true);
hash = digest.digest();
}
public byte[] getHash() {
return hash;
}
public boolean isUsed() {
return used;
}
}