java.security
class DigestOutputStream

java.lang.Object java.io.OutputStream java.io.FilterOutputStream java.security.DigestOutputStream

All Implemented Interfaces:

Closeable, Flushable

Most common way to construct:

ByteArrayOutputStream baos = …;
MessageDigest md = …;

DigestOutputStream dos = new DigestOutputStream(baos, md);

Based on 9 examples

public class DigestOutputStream
extends FilterOutputStream

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 ouput stream's {@link #write(int) write} methods.

It is possible to turn this stream on or off (see {@link #on(boolean) on}). When it is on, a call to one of the write 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.

digest

protected MessageDigest digest

The message digest associated with this stream.

DigestOutputStream

public DigestOutputStream(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.

getMessageDigest

public MessageDigest getMessageDigest()

Returns the message digest associated with this stream.

Returns:

the message digest associated with this stream.

on

public void on(boolean on)

Turns the digest function on or off. The default is on. When it is on, a call to one of the write 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 turn it off.

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.

toString

public String toString()

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

Overrides:

toString in class Object

write

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

Updates the message digest (if the digest function is on) using the specified subarray, and in any case writes the subarray to the output stream. That is, if the digest function is on (see {@link #on(boolean) on}), this method calls update on the message digest associated with this stream, passing it the subarray specifications. This method then writes the subarray bytes to the output stream, blocking until the bytes are actually written.

Overrides:

write in class FilterOutputStream

Parameters:

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

off - the offset into b of the first byte to be updated and written.

len - the number of bytes of data to be updated and written from b, starting at offset off.

Throws:

IOException - if an I/O error occurs.

write

public void write(int b)
           throws IOException

Updates the message digest (if the digest function is on) using the specified byte, and in any case writes the byte to the output stream. That is, if the digest function is on (see {@link #on(boolean) on}), this method calls update on the message digest associated with this stream, passing it the byte b. This method then writes the byte to the output stream, blocking until the byte is actually written.

Overrides:

write in class FilterOutputStream

Parameters:

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

Throws:

IOException - if an I/O error occurs.