edu.harvard.hul.ois.jhove
Class ChecksumInputStream

java.lang.Object
  java.io.InputStream
      java.io.FilterInputStream
          edu.harvard.hul.ois.jhove.ChecksumInputStream

All Implemented Interfaces:

java.io.Closeable

public class ChecksumInputStream
extends java.io.FilterInputStream

A ChecksumInputStream is a FilterInputStream with the added functionality of calculating checksums as it goes. The idea of replacing this with java.util.zip.CheckedInputStream looks very tempting, but we need the byte count, which CheckedInputStream doesn't provide.

Author:

Gary McGath

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

ChecksumInputStream(java.io.InputStream stream, Checksummer cksummer)
Constructor.

Method Summary

void	close() Closes the subsumed stream.
Checksummer	getChecksummer() Returns the Checksummer object.
long	getNBytes() Returns the byte count to date on the stream.
int	read() Reads a byte from the subsumed stream, updating the byte count and the checksums.
int	read(byte[] b) Reads some number of bytes from the input stream and stores them into the buffer array b.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from the input stream into an array of bytes.
long	skip(long n) Skips n bytes.

Methods inherited from class java.io.FilterInputStream

available, mark, markSupported, reset

Methods inherited from class java.lang.Object

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

Constructor Detail

ChecksumInputStream

public ChecksumInputStream(java.io.InputStream stream,
                           Checksummer cksummer)

Constructor.

Parameters:

stream - Stream to be filtered

cksummer - Object to calculate checksum on the bytes as they are read

Method Detail

read

public int read()
         throws java.io.IOException

Reads a byte from the subsumed stream, updating the byte count and the checksums.

Overrides:

read in class java.io.FilterInputStream

Throws:

java.io.IOException

read

public int read(byte[] b)
         throws java.io.IOException

Reads some number of bytes from the input stream and stores them into the buffer array b. The number of bytes actually read is returned as an integer. All bytes read are fed through the checksummer.

Overrides:

read in class java.io.FilterInputStream

Throws:

java.io.IOException

read

public int read(byte[] b,
                int off,
                int len)
         throws java.io.IOException

Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read, possibly zero. The number of bytes actually read is returned as an integer. All bytes read are fed through the checksummer.

Overrides:

read in class java.io.FilterInputStream

Throws:

java.io.IOException

skip

public long skip(long n)
          throws java.io.IOException

Skips n bytes. Reads them and feeds them through the checksummer.

Overrides:

skip in class java.io.FilterInputStream

Throws:

java.io.IOException

close

public void close()
           throws java.io.IOException

Closes the subsumed stream.

Specified by:

close in interface java.io.Closeable

Overrides:

close in class java.io.FilterInputStream

Throws:

java.io.IOException

getNBytes

public long getNBytes()

Returns the byte count to date on the stream. This returns the number of bytes read. Because of buffering, this is not a reliable indicator of how many bytes have actually been processed.

getChecksummer

public Checksummer getChecksummer()

Returns the Checksummer object.