java.security

Class DigestOutputStream

java.lang.Object

java.io.OutputStream

java.io.FilterOutputStream

java.security.DigestOutputStream

All Implemented Interfaces:

Closeable, Flushable, AutoCloseable

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

Fields

Modifier and Type	Field and Description
protected MessageDigest	digest The message digest for the DigestOutputStream

Fields inherited from class java.io.FilterOutputStream

out

Constructor Summary

Constructors

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

Method Summary

Methods

Modifier and Type	Method and Description
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

Methods inherited from class java.lang.Object

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

Field Detail

digest

protected MessageDigest digest

The message digest for the DigestOutputStream

Constructor Detail

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 Detail

getMessageDigest

public MessageDigest getMessageDigest()

Returns the MessageDigest associated with this DigestOutputStream

Returns:

The MessageDigest used to hash this stream

setMessageDigest

public void setMessageDigest(MessageDigest digest)

Sets the current MessageDigest to current parameter

Parameters:

digest - A MessageDigest to associate with this stream

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 class 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.

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 class 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.

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

toString

public String toString()

Converts the output stream and underlying message digest to a string.

Overrides:

toString in class Object

Returns:

A string representing the output stream and message digest.

See Also:

Object.getClass(), Object.hashCode(), Class.getName(), Integer.toHexString(int)