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java.security

Class DigestOutputStream

Implemented Interfaces:
Closeable, Flushable
public class DigestOutputStream
extends FilterOutputStream
DigestOutputStream is a class that ties an OutputStream with a MessageDigest. The Message Digest is used by the class to update it self as bytes are written to the OutputStream. The updating to the digest depends on the on flag which is set to true by default that tells the class to update the data in the message digest.

Field Summary

protected MessageDigest
digest
The message digest for the DigestOutputStream

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

DigestOutputStream(OutputStream stream, MessageDigest digest)
Constructs a new DigestOutputStream.

Method Summary

MessageDigest
getMessageDigest()
Returns the MessageDigest associated with this DigestOutputStream
void
on(boolean on)
Sets the flag specifying if this DigestOutputStream updates the digest in the write() methods.
void
setMessageDigest(MessageDigest digest)
Sets the current MessageDigest to current parameter
String
toString()
Converts the output stream and underlying message digest to a string.
void
write(byte[] b, int off, int len)
Updates the hash if the on flag is true and then writes the bytes to the underlying output stream.
void
write(int b)
Updates the hash if the on flag is true and then writes a byte to the underlying output stream.

Methods inherited from class java.io.FilterOutputStream

close, flush, write, write, write

Methods inherited from class java.io.OutputStream

close, flush, write, write, write

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

digest

protected MessageDigest digest
The message digest for the DigestOutputStream

Constructor Details

DigestOutputStream

public DigestOutputStream(OutputStream stream,
                          MessageDigest digest)
Constructs a new DigestOutputStream. It associates a MessageDigest with the stream to compute the stream as data is written.
Parameters:
stream - An OutputStream to associate this stream with
digest - A MessageDigest to hash the stream with

Method Details

getMessageDigest

public MessageDigest getMessageDigest()
Returns the MessageDigest associated with this DigestOutputStream
Returns:
The MessageDigest used to hash this stream

on

public void on(boolean on)
Sets the flag specifying if this DigestOutputStream updates the digest in the write() methods. The default is on;
Parameters:
on - True means it digests stream, false means it does not

setMessageDigest

public void setMessageDigest(MessageDigest digest)
Sets the current MessageDigest to current parameter
Parameters:
digest - A MessageDigest to associate with this stream

toString

public String toString()
Converts the output stream and underlying message digest to a string.
Overrides:
toString in interface Object
Returns:
A string representing the output stream and message digest.

write

public void write(byte[] b,
                  int off,
                  int len)
            throws IOException
Updates the hash if the on flag is true and then writes the bytes to the underlying output stream.
Overrides:
write in interface FilterOutputStream
Parameters:
b - Bytes to write to the output stream
off - Offset to start to start at in array
len - Length of data to write
Throws:
IOException - if the underlying output stream cannot write the bytes, this is thrown.

write

public void write(int b)
            throws IOException
Updates the hash if the on flag is true and then writes a byte to the underlying output stream.
Overrides:
write in interface FilterOutputStream
Parameters:
b - A byte to write to the output stream
Throws:
IOException - if the underlying output stream cannot write the byte, this is thrown.
DigestOutputStream.java --- An output stream tied to a message digest Copyright (C) 1999, 2004, 2005 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.

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