88 lines
2.5 KiB
Java
88 lines
2.5 KiB
Java
package tc.oc.commons.core.util;
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import com.google.common.hash.HashCode;
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import com.google.common.hash.HashFunction;
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import com.google.common.hash.Hasher;
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import java.io.FilterInputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import static com.google.common.base.Preconditions.checkNotNull;
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/**
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* TODO: This is copypast from Guava - use the real one when we upgrade
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*/
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public class HashingInputStream extends FilterInputStream {
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private final Hasher hasher;
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/**
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* Creates an input stream that hashes using the given {@link com.google.common.hash.HashFunction} and delegates all data
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* read from it to the underlying {@link java.io.InputStream}.
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*
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* <p>The {@link java.io.InputStream} should not be read from before or after the hand-off.
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*/
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public HashingInputStream(HashFunction hashFunction, InputStream in) {
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super(checkNotNull(in));
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this.hasher = checkNotNull(hashFunction.newHasher());
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}
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/**
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* Reads the next byte of data from the underlying input stream and updates the hasher with
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* the byte read.
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*/
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@Override
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public int read() throws IOException {
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int b = in.read();
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if (b != -1) {
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hasher.putByte((byte) b);
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}
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return b;
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}
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/**
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* Reads the specified bytes of data from the underlying input stream and updates the hasher with
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* the bytes read.
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*/
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@Override
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public int read(byte[] bytes, int off, int len) throws IOException {
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int numOfBytesRead = in.read(bytes, off, len);
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if (numOfBytesRead != -1) {
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hasher.putBytes(bytes, off, numOfBytesRead);
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}
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return numOfBytesRead;
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}
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/**
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* mark() is not supported for HashingInputStream
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* @return {@code false} always
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*/
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@Override
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public boolean markSupported() {
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return false;
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}
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/**
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* mark() is not supported for HashingInputStream
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*/
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@Override
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public void mark(int readlimit) {}
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/**
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* reset() is not supported for HashingInputStream.
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* @throws IOException this operation is not supported
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*/
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@Override
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public void reset() throws IOException {
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throw new IOException("reset not supported");
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}
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/**
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* Returns the {@link com.google.common.hash.HashCode} based on the data read from this stream. The result is
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* unspecified if this method is called more than once on the same instance.
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*/
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public HashCode hash() {
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return hasher.hash();
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}
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}
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