Package com.google.common.hash

Class HashingInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

com.google.common.hash.HashingInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

@Beta
public final class HashingInputStream
extends FilterInputStream

An InputStream that maintains a hash of the data read from it.

Since:

16.0

Author:

Qian Huang

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

Constructors

Constructor	Description
HashingInputStream(HashFunction hashFunction, InputStream in)	Creates an input stream that hashes using the given HashFunction and delegates all data read from it to the underlying InputStream.

Method Summary

Modifier and Type	Method	Description
HashCode	hash()	Returns the HashCode based on the data read from this stream.
void	mark(int readlimit)	mark() is not supported for HashingInputStream
boolean	markSupported()	mark() is not supported for HashingInputStream
int	read()	Reads the next byte of data from the underlying input stream and updates the hasher with the byte read.
int	read(byte[] bytes, int off, int len)	Reads the specified bytes of data from the underlying input stream and updates the hasher with the bytes read.
void	reset()	reset() is not supported for HashingInputStream.

Methods inherited from class java.io.FilterInputStream

available, close, read, skip

Methods inherited from class java.io.InputStream

nullInputStream, readAllBytes, readNBytes, readNBytes, transferTo

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HashingInputStream

public HashingInputStream(HashFunction hashFunction,
                          InputStream in)

Creates an input stream that hashes using the given HashFunction and delegates all data read from it to the underlying InputStream.

The InputStream should not be read from before or after the hand-off.

Method Detail

read

@CanIgnoreReturnValue
public int read()
         throws IOException

Reads the next byte of data from the underlying input stream and updates the hasher with the byte read.

Overrides:

read in class FilterInputStream

Returns:

the next byte of data, or -1 if the end of the stream is reached.

Throws:

IOException - if an I/O error occurs.

See Also:

FilterInputStream.in

read

@CanIgnoreReturnValue
public int read(byte[] bytes,
                int off,
                int len)
         throws IOException

Reads the specified bytes of data from the underlying input stream and updates the hasher with the bytes read.

Overrides:

read in class FilterInputStream

Parameters:

bytes - the buffer into which the data is read.

off - the start offset in the destination array b

len - the maximum number of bytes read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the stream has been reached.

Throws:

IOException - if an I/O error occurs.

See Also:

FilterInputStream.in

markSupported

public boolean markSupported()

mark() is not supported for HashingInputStream

Overrides:

markSupported in class FilterInputStream

Returns:

false always

See Also:

FilterInputStream.in, InputStream.mark(int), InputStream.reset()

mark

public void mark(int readlimit)

mark() is not supported for HashingInputStream

Overrides:

mark in class FilterInputStream

Parameters:

readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid.

See Also:

FilterInputStream.in, FilterInputStream.reset()

reset

public void reset()
           throws IOException

reset() is not supported for HashingInputStream.

Overrides:

reset in class FilterInputStream

Throws:

IOException - this operation is not supported

See Also:

FilterInputStream.in, FilterInputStream.mark(int)

hash

public HashCode hash()

Returns the HashCode based on the data read from this stream. The result is unspecified if this method is called more than once on the same instance.