jut.io
Class HashInputStream

java.lang.Object
  java.io.InputStream
      jut.io.InputCountStream
          jut.io.HashInputStream

All Implemented Interfaces:

Closeable

public class HashInputStream
extends InputCountStream

InputStream calculating a hash for the bytes read. the methods InputCountStream.skip(long), InputCountStream.mark(int) and InputCountStream.reset() are not supported and throw an UnsupportedOperationException.

Field Summary

Fields inherited from class jut.io.InputCountStream

baseStream, counter

Constructor Summary

HashInputStream(File file, String algorithm)
create a new InputStream calculating a hash for the bytes read. for creating the stream, the Streams.input(File) method is used.

HashInputStream(File file, String algorithm, int capacity)
create a new InputStream with push back functionality calculating a hash for the bytes read. for creating the stream, the Streams.input(File) method is used.

HashInputStream(InputStream stream, String algorithm)
create a new InputStream calculating a hash for the bytes read.

HashInputStream(InputStream stream, String algorithm, int capacity)
create a new InputStream with push back functionality calculating a hash for the bytes read. if the hash algorithm is not provided, an appropriate NestedException is thrown.

Method Summary

void	close() the HashInputStream must be closed before the hash result can be read.
String	hash() returns the hash string for this HashInputStream. note that the HashInputStream must be closed before the hash result can be read.
byte[]	hashDigest() returns the hash digest for this HashInputStream. note that the HashInputStream must be closed before the hash result can be read.
Long	lastModified() returns the modification time stamp of the underlying file if known, else null.
void	unread(byte[] bytes) pushes back an array of bytes by copying it to the front of the pushback buffer. note that the hash is created from the data read originally, i.e., if data different from the data read is pushed back and read again, the hash does not change.
void	unread(byte[] bytes, int off, int len) pushes back a portion of an array of bytes by copying it to the front of the pushback buffer.
void	unread(int oneByte) pushes back a byte by copying it to the front of the pushback buffer. note that the hash is created from the data read originally, i.e., if data different from the data read is pushed back and read again, the hash does not change.

Methods inherited from class jut.io.InputCountStream

available, getCount, getCounter, mark, markSupported, read, read, read, reset, skip

Methods inherited from class java.lang.Object

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

Constructor Detail

HashInputStream

public HashInputStream(File file,
                       String algorithm)
                throws FileNotFoundException

create a new InputStream calculating a hash for the bytes read. for creating the stream, the Streams.input(File) method is used.

Parameters:

file - - the file to open the InputStream for.

algorithm - - the hash algorithm to use as defined in MessageDigest.getAlgorithm()

Throws:

FileNotFoundException - if the file cannot be opened for reading.

HashInputStream

public HashInputStream(InputStream stream,
                       String algorithm)

create a new InputStream calculating a hash for the bytes read.

Parameters:

stream - - the stream to calculate a hash for.

algorithm - - the hash algorithm to use as defined in MessageDigest.getAlgorithm()

HashInputStream

public HashInputStream(File file,
                       String algorithm,
                       int capacity)
                throws FileNotFoundException

create a new InputStream with push back functionality calculating a hash for the bytes read. for creating the stream, the Streams.input(File) method is used.

Parameters:

file - - the file to open the InputStream for.

algorithm - - the hash algorithm to use as defined in MessageDigest.getAlgorithm()

capacity - - the capacity of the push back buffer as defined in PushbackInputStream.

Throws:

FileNotFoundException - if the file cannot be opened for reading.

HashInputStream

public HashInputStream(InputStream stream,
                       String algorithm,
                       int capacity)

create a new InputStream with push back functionality calculating a hash for the bytes read. if the hash algorithm is not provided, an appropriate NestedException is thrown.

Parameters:

stream - - the stream to calculate a hash for.

algorithm - - the hash algorithm to use as defined in MessageDigest.getAlgorithm()

capacity - - the capacity of the push back buffer as defined in PushbackInputStream.

Method Detail

unread

public void unread(byte[] bytes)
            throws IOException

pushes back an array of bytes by copying it to the front of the pushback buffer. note that the hash is created from the data read originally, i.e., if data different from the data read is pushed back and read again, the hash does not change.

Parameters:

bytes - - the byte array to push back.

Throws:

IOException - if there is not enough room in the pushback buffer for the specified number of bytes, or this input stream has been closed by invoking its close() method.

unread

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

pushes back a portion of an array of bytes by copying it to the front of the pushback buffer. note that the hash is created from the data read originally, i.e., if data different from the data read is pushed back and read again, the hash does not change.

Parameters:

bytes - - the byte array to push back.

off - - the start offset of the data.

len - - the number of bytes to push back.

Throws:

IOException - if there is not enough room in the pushback buffer for the specified number of bytes, or this input stream has been closed by invoking its close() method.

unread

public void unread(int oneByte)
            throws IOException

pushes back a byte by copying it to the front of the pushback buffer. note that the hash is created from the data read originally, i.e., if data different from the data read is pushed back and read again, the hash does not change.

Parameters:

oneByte - - the int value whose low-order byte is to be pushed back.

Throws:

IOException - if there is not enough room in the pushback buffer for the byte, or this input stream has been closed by invoking its close() method.

close

public void close()
           throws IOException

the HashInputStream must be closed before the hash result can be read.

Specified by:

close in interface Closeable

Overrides:

close in class InputCountStream

Throws:

IOException

hashDigest

public byte[] hashDigest()
                  throws IllegalStateException

returns the hash digest for this HashInputStream. note that the HashInputStream must be closed before the hash result can be read.

Returns:

the hash digest for this HashInputStream.

Throws:

IllegalStateException - if trying to access the hash result while the stream is still open.

hash

public String hash()
            throws IllegalStateException

returns the hash string for this HashInputStream. note that the HashInputStream must be closed before the hash result can be read.

Returns:

the hash string for this HashInputStream.

Throws:

IllegalStateException - if trying to access the hash result while the stream is still open.

lastModified

public Long lastModified()

returns the modification time stamp of the underlying file if known, else null.

Returns:

the modification time stamp of the underlying file if known, else null.