com.novell.java.security
Class DigestOutputStream

java.lang.Object
  |
  +--java.io.OutputStream
        |
        +--java.io.FilterOutputStream
              |
              +--com.novell.java.security.DigestOutputStream

public class DigestOutputStream

extends java.io.FilterOutputStream

Provides 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 calling one of this digest ouput stream's write() methods.

It is possible to turn this stream ON or OFF by calling the on() method. When it is ON, a call to write() results in an update on the message digest. When the output stream is OFF, the message digest is not updated. The default is for the stream to be ON.

See Also:

MessageDigest, DigestInputStream

Constructor Summary

DigestOutputStream(java.io.OutputStream stream, MessageDigest digest)
Creates a digest output stream using the specified output stream and message digest.

Method Summary

MessageDigest	getMessageDigest() Returns the message digest associated with this stream.
void	on(boolean on) Turns the digest function ON (default) or OFF.
void	setMessageDigest(MessageDigest digest) Associates the specified message digest with this stream.
java.lang.String	toString() Prints a String representation of this digest output stream and its associated message digest object.
void	write(byte[] b, int off, int len) Updates the message digest using the specified subarray, and writes the subarray to the output stream.
void	write(int b) Updates the message digest using the specified byte.

Methods inherited from class java.io.FilterOutputStream

close, flush, write

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

DigestOutputStream

public DigestOutputStream(java.io.OutputStream stream,
                          MessageDigest digest)

Creates a digest output stream using the specified output stream and message digest.

Parameters:

stream - The output stream.

digest - The message digest to associate with this stream.

Method Detail

getMessageDigest

public MessageDigest getMessageDigest()

Returns the message digest associated with this stream.

Returns:

The message digest associated with this stream.

setMessageDigest

public void setMessageDigest(MessageDigest digest)

Associates the specified message digest with this stream.

Parameters:

digest - The message digest to be associated with this stream.

write

public void write(int b)
           throws java.io.IOException

Updates the message digest using the specified byte. The update is done only if the digest function is ON. Following the update the byte is written to the output stream. If the digest function is set to ON by the on() method, the write method calls the update() method on the message digest associated with this stream, passing it the byte b. The byte is then written to the output stream, blocking until the byte is actually written.

Parameters:

b - The byte to be used for updating and writing to the output stream.

Throws:

java.io.IOException - Thrown if an I/O error occurs.

Overrides:

write in class java.io.FilterOutputStream

See Also:

MessageDigest.update(byte)

write

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

Updates the message digest using the specified subarray, and writes the subarray to the output stream. The update is done only if the digest function is set to ON by calling the on() method. That is, if the digest function is ON, this write() method calls update() on the message digest associated with this stream, passing it the subarray specifications. This write() method then writes the subarray bytes to the output stream, blocking until the bytes are actually written.

Parameters:

b - The array containing the subarray to be used for updating and writing to the output stream.

off - The offset into the byte array (b[]) of the first byte to be updated and written.

len - The number of bytes of data to be updated and written from the byte array (b[]), starting at offset specified by the off parameter.

Throws:

java.io.IOException - if an I/O error occurs.

Overrides:

write in class java.io.FilterOutputStream

See Also:

MessageDigest.update(byte[], int, int)

on

public void on(boolean on)

Turns the digest function ON (default) or OFF. When it is on, a call to the write() function results in an update on the message digest. When the digest function is OFF the message digest is not updated.

Parameters:

on - A boolean set to TRUE to turn the digest function ON, and FALSE to turn it OFF.

toString

public java.lang.String toString()

Prints a String representation of this digest output stream and its associated message digest object.

Overrides:

toString in class java.lang.Object