net.jini.url.httpmd

Class MdInputStream

java.lang.Object

java.io.InputStream

net.jini.url.httpmd.MdInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

 class MdInputStream
extends InputStream

An input stream that checks the contents of another input stream against a message digest. The stream throws WrongMessageDigestException if the end of the other input stream is reached and the contents did not have the expected message digest. The message digest is not checked unless the end of the input stream is reached.

Author:

Sun Microsystems, Inc.

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	checked Set to true when the contents have been checked against the message digest.
private byte[]	expectedDigest The expected digest.
private String	failed The exception message if the message digest was incorrect, or null if no exception should be thrown.
private InputStream	in The input stream whose contents should be checked.
private static Logger	logger Logger.
private MessageDigest	messageDigest The object to use to compute the message digest of the stream contents.
private static int	SKIP_BUFFER_SIZE The size buffer to use when skipping input.
private byte[]	skipBuffer Set to the buffer to use when skipping input.
private URL	url The HTTPMD URL associated with the input stream being checked.

Constructor Summary

Constructors

Constructor and Description
MdInputStream(URL url, InputStream in, MessageDigest messageDigest, byte[] expectedDigest) Creates an input stream that checks the contents of another input stream against a message digest.

Method Summary

Methods

Modifier and Type	Method and Description
int	available()
private void	checkDigest() Checks the message digest.
private void	checkFailed() Throws an exception if the message digest was found to be incorrect.
void	close()
int	read()
int	read(byte[] b, int off, int len)
long	skip(long n)

Methods inherited from class java.io.InputStream

mark, markSupported, read, reset

Methods inherited from class java.lang.Object

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

Field Detail

logger

private static final Logger logger

Logger.

SKIP_BUFFER_SIZE

private static final int SKIP_BUFFER_SIZE

The size buffer to use when skipping input.

See Also:

Constant Field Values

url

private final URL url

The HTTPMD URL associated with the input stream being checked.

in

private final InputStream in

The input stream whose contents should be checked.

messageDigest

private final MessageDigest messageDigest

The object to use to compute the message digest of the stream contents.

expectedDigest

private final byte[] expectedDigest

The expected digest.

skipBuffer

private byte[] skipBuffer

Set to the buffer to use when skipping input.

checked

private boolean checked

Set to true when the contents have been checked against the message digest.

failed

private String failed

The exception message if the message digest was incorrect, or null if no exception should be thrown.

Constructor Detail

MdInputStream

MdInputStream(URL url,
             InputStream in,
             MessageDigest messageDigest,
             byte[] expectedDigest)

Creates an input stream that checks the contents of another input stream against a message digest. The stream throws WrongMessageDigestException if the end of the other input stream is reached and the contents did not have the expected message digest.

Parameters:

url - the HTTPMD URL associated with the input stream being checked

in - the input stream whose contents should be checked

messageDigest - the object to use for computing the message digest of the stream contents

expectedDigest - the expected message digest of the stream contents

Throws:

NullPointerException - if any of the arguments is null

Method Detail

read

public int read()
         throws IOException

Specified by:

read in class InputStream

Throws:

IOException

checkFailed

private void checkFailed()
                  throws WrongMessageDigestException

Throws an exception if the message digest was found to be incorrect. Call this method before performing any I/O operations to insure that the same exception continues to be thrown after an incorrect message digest is discovered.

Throws:

WrongMessageDigestException

checkDigest

private void checkDigest()
                  throws WrongMessageDigestException

Checks the message digest. Call this method when the end of the other input stream is reached.

Throws:

WrongMessageDigestException

read

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

Overrides:

read in class InputStream

Throws:

IOException

skip

public long skip(long n)
          throws IOException

Overrides:

skip in class InputStream

Throws:

IOException

available

public int available()
              throws IOException

Overrides:

available in class InputStream

Throws:

IOException

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class InputStream

Throws:

IOException