| java.lang.Object
 java.io.InputStream
java.io.FilterInputStream
java.security.DigestInputStream
| DigestInputStream | | public class DigestInputStream extends FilterInputStream (Code) | | A transparent stream that updates the associated message digest using
the bits going through the stream.
To complete the message digest computation, call one of the
digest methods on the associated message
digest after your calls to one of this digest input stream's
DigestInputStream.read() read methods.
It is possible to turn this stream on or off (see
DigestInputStream.on(boolean) on ). When it is on, a call to one of the
read methods
results in an update on the message digest. But when it is off,
the message digest is not updated. The default is for the stream
to be on.
Note that digest objects can compute only one digest (see
MessageDigest ),
so that in order to compute intermediate digests, a caller should
retain a handle onto the digest object, and clone it for each
digest to be computed, leaving the orginal digest untouched.
See Also: MessageDigest
See Also: DigestOutputStream
version:
1.34 00/02/02
author:
Benjamin Renaud |
| Method Summary | |
| public MessageDigest | getMessageDigest()
Returns the message digest associated with this stream. | | public void | on(boolean on)
Turns the digest function on or off. | | public int | read()
Reads a byte, and updates the message digest (if the digest
function is on). | | public int | read(byte[] b, int off, int len)
Reads into a byte array, and updates the message digest (if the
digest function is on). | | public void | setMessageDigest(MessageDigest digest)
Associates the specified message digest with this stream. | | public String | toString()
Prints a string representation of this digest input stream and
its associated message digest object. |
| DigestInputStream | | public DigestInputStream(InputStream stream, MessageDigest digest)(Code) | | Creates a digest input stream, using the specified input stream
and message digest.
Parameters:
stream - the input stream.
Parameters:
digest - the message digest to associate with this stream. |
| on | | public void on(boolean on)(Code) | | Turns the digest function on or off. The default is on. When
it is on, a call to one of the read methods results in an
update on the message digest. But when it is off, the message
digest is not updated.
Parameters:
on - true to turn the digest function on, false to turnit off. |
| read | | public int read() throws IOException(Code) | | Reads a byte, and updates the message digest (if the digest
function is on). That is, this method reads a byte from the
input stream, blocking until the byte is actually read. If the
digest function is on (see
DigestInputStream.on(boolean) on ), this method
will then call update on the message digest associated
with this stream, passing it the byte read.
the byte read.
exception:
IOException - if an I/O error occurs.
See Also: MessageDigest.update(byte) |
| read | | public int read(byte[] b, int off, int len) throws IOException(Code) | | Reads into a byte array, and updates the message digest (if the
digest function is on). That is, this method reads up to
len bytes from the input stream into the array
b, starting at offset off. This method
blocks until the data is actually
read. If the digest function is on (see
DigestInputStream.on(boolean) on ), this method will then call update
on the message digest associated with this stream, passing it
the data.
Parameters:
b - the array into which the data is read.
Parameters:
off - the starting offset into b of where thedata should be placed.
Parameters:
len - the maximum number of bytes to be read from the inputstream into b, starting at offset off. the actual number of bytes read. This is less thanlen if the end of the stream is reached prior toreading len bytes. -1 is returned if no bytes wereread because the end of the stream had already been reached whenthe call was made.
exception:
IOException - if an I/O error occurs.
See Also: MessageDigest.update(byte[]intint) |
| toString | | public String toString()(Code) | | Prints a string representation of this digest input stream and
its associated message digest object.
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