java.util.zip
Class CheckedInputStream

java.lang.Object
  java.io.InputStream
      java.io.FilterInputStream
          java.util.zip.CheckedInputStream

All Implemented Interfaces:

Closeable

public class CheckedInputStream
extends FilterInputStream

The CheckedInputStream class is used to maintain a running Checksum of all data read from a stream.

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

CheckedInputStream(InputStream is, Checksum csum)
Constructs a new CheckedInputStream on InputStream is.

Method Summary

Checksum	getChecksum() Returns the Checksum calculated on the stream thus far.
int	read() Reads a byte of data from the underlying stream and recomputes the Checksum with the byte data.
int	read(byte[] buf, int off, int nbytes) Reads up to nbytes of data from the underlying stream, storing it in buf, starting at offset off.
long	skip(long nbytes) Skip upto nbytes of data on the underlying stream.

Methods inherited from class java.io.FilterInputStream

available, close, mark, markSupported, read, reset

Methods inherited from class java.lang.Object

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

Constructor Detail

CheckedInputStream

public CheckedInputStream(InputStream is,
                          Checksum csum)

Constructs a new CheckedInputStream on InputStream is. The Checksum will be calculated using the algorithm implemented by csum.

Parameters:

is - InputStream to calculate checksum from

csum - Type of Checksum to calculate

Method Detail

read

public int read()
         throws IOException

Reads a byte of data from the underlying stream and recomputes the Checksum with the byte data.

Overrides:

read in class FilterInputStream

Returns:

-1 if end of stream, a single byte value otherwise

Throws:

IOException - If the stream is already closed or another IOException occurs.

read

public int read(byte[] buf,
                int off,
                int nbytes)
         throws IOException

Reads up to nbytes of data from the underlying stream, storing it in buf, starting at offset off. The Checksum is updated with the bytes read.

Overrides:

read in class FilterInputStream

Parameters:

buf - the byte array in which to store the read bytes.

off - the offset in buffer to store the read bytes.

nbytes - the maximum number of bytes to store in buffer.

Returns:

Number of bytes read, -1 if end of stream

Throws:

IOException - If the stream is already closed or another IOException occurs.

getChecksum

public Checksum getChecksum()

Returns the Checksum calculated on the stream thus far.

Returns:

A java.util.zip.Checksum

skip

public long skip(long nbytes)
          throws IOException

Skip upto nbytes of data on the underlying stream. Any skipped bytes are added to the running Checksum value.

Overrides:

skip in class FilterInputStream

Parameters:

nbytes - long Number of bytes to skip

Returns:

Number of bytes skipped

Throws:

IOException - If the stream is already closed or another IOException occurs.