com.google.common.hash

Class HashingOutputStream

java.lang.Object

java.io.OutputStream

java.io.FilterOutputStream

com.google.common.hash.HashingOutputStream

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

@Beta
public final class HashingOutputStream
extends FilterOutputStream

An OutputStream that maintains a hash of the data written to it.

Since:

16.0

Author:

Nick Piepmeier

Field Summary

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

Constructors

Constructor and Description
HashingOutputStream(HashFunction hashFunction, OutputStream out) Creates an output stream that hashes using the given HashFunction, and forwards all data written to it to the underlying OutputStream.

Method Summary

Modifier and Type	Method and Description
void	close() Closes this output stream and releases any system resources associated with the stream.
HashCode	hash() Returns the HashCode based on the data written to this stream.
void	write(byte[] bytes, int off, int len) Writes len bytes from the specified byte array starting at offset off to this output stream.
void	write(int b) Writes the specified byte to this output stream.

Methods inherited from class java.io.FilterOutputStream

flush, write

Methods inherited from class java.lang.Object

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

Constructor Detail

HashingOutputStream

public HashingOutputStream(HashFunction hashFunction,
                           OutputStream out)

Creates an output stream that hashes using the given HashFunction, and forwards all data written to it to the underlying OutputStream.

The OutputStream should not be written to before or after the hand-off.

Method Detail

write

public void write(int b)
           throws IOException

Description copied from class: java.io.FilterOutputStream

Writes the specified byte to this output stream.

The write method of FilterOutputStream calls the write method of its underlying output stream, that is, it performs out.write(b).

Implements the abstract write method of OutputStream.

Overrides:

write in class FilterOutputStream

Parameters:

b - the byte.

Throws:

IOException - if an I/O error occurs.

write

public void write(byte[] bytes,
                  int off,
                  int len)
           throws IOException

Description copied from class: java.io.FilterOutputStream

Writes len bytes from the specified byte array starting at offset off to this output stream.

The write method of FilterOutputStream calls the write method of one argument on each byte to output.

Note that this method does not call the write method of its underlying input stream with the same arguments. Subclasses of FilterOutputStream should provide a more efficient implementation of this method.

Overrides:

write in class FilterOutputStream

Parameters:

bytes - the data.

off - the start offset in the data.

len - the number of bytes to write.

Throws:

IOException - if an I/O error occurs.

See Also:

FilterOutputStream.write(int)

hash

public HashCode hash()

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

close

public void close()
           throws IOException

Description copied from class: java.io.FilterOutputStream

Closes this output stream and releases any system resources associated with the stream.

The close method of FilterOutputStream calls its flush method, and then calls the close method of its underlying output stream.

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class FilterOutputStream

Throws:

IOException - if an I/O error occurs.

See Also:

FilterOutputStream.flush(), FilterOutputStream.out