java.util.zip

Class CheckedInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

java.util.zip.CheckedInputStream

public class CheckedInputStream
extends FilterInputStream

InputStream that computes a checksum of the data being read using a supplied Checksum object.

Author:

Tom Tromey

See Also:

Checksum

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

Constructors

Constructor and Description
CheckedInputStream(InputStream in, Checksum sum) Creates a new CheckInputStream on top of the supplied OutputStream using the supplied Checksum.

Method Summary

Modifier and Type	Method and Description
Checksum	getChecksum() Returns the Checksum object used.
int	read() Reads one byte, updates the checksum and returns the read byte (or -1 when the end of file was reached).
int	read(byte[] buf, int off, int len) Reads at most len bytes in the supplied buffer and updates the checksum with it.
long	skip(long n) Skips n bytes by reading them in a temporary buffer and updating the the checksum with that buffer.

Methods inherited from class java.io.FilterInputStream

available, close, mark, markSupported, read, reset

Methods inherited from class java.io.InputStream

finalize, hashCode

Methods inherited from class java.lang.Object

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

Constructor Detail

CheckedInputStream

public CheckedInputStream(InputStream in,
                          Checksum sum)

Creates a new CheckInputStream on top of the supplied OutputStream using the supplied Checksum.

Method Detail

getChecksum

public Checksum getChecksum()

Returns the Checksum object used. To get the data checksum computed so far call getChecksum.getValue().

read

public int read()
         throws IOException

Reads one byte, updates the checksum and returns the read byte (or -1 when the end of file was reached).

Overrides:

read in class FilterInputStream

Returns:

The value returned from in.read()

Throws:

IOException - If an error occurs

read

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

Reads at most len bytes in the supplied buffer and updates the checksum with it. Returns the number of bytes actually read or -1 when the end of file was reached.

Overrides:

read in class FilterInputStream

Parameters:

buf - The buffer to read bytes into

off - The index into the buffer to start storing bytes

len - The maximum number of bytes to read.

Returns:

The value retured from in.read(byte[], int, int)

Throws:

IOException - If an error occurs

skip

public long skip(long n)
          throws IOException

Skips n bytes by reading them in a temporary buffer and updating the the checksum with that buffer. Returns the actual number of bytes skiped which can be less then requested when the end of file is reached.

Overrides:

skip in class FilterInputStream

Parameters:

n - The requested number of bytes to skip

Returns:

The value returned from in.skip(long)

Throws:

IOException - If an error occurs