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package java.security;
import java.io.IOException;
import java.io.EOFException;
import java.io.OutputStream;
import java.io.FilterOutputStream;
import java.io.PrintStream;
import java.io.ByteArrayOutputStream;
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 output stream's write methods.
It is possible to turn this stream on or off (see 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.
Author: Benjamin Renaud See Also: Since: 1.2
/**
* A transparent stream that updates the associated message digest using
* the bits going through the stream.
*
* <p>To complete the message digest computation, call one of the
* {@code digest} methods on the associated message
* digest after your calls to one of this digest output stream's
* {@link #write(int) write} methods.
*
* <p>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
* {@code 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.
*
* @see MessageDigest
* @see DigestInputStream
*
* @author Benjamin Renaud
* @since 1.2
*/
public class DigestOutputStream extends FilterOutputStream {
private boolean on = true;
The message digest associated with this stream.
/**
* The message digest associated with this stream.
*/
protected MessageDigest digest;
Creates a digest output stream, using the specified output stream
and message digest.
Params: - stream – the output stream.
- digest – the message digest to associate with this stream.
/**
* Creates a digest output stream, using the specified output stream
* and message digest.
*
* @param stream the output stream.
*
* @param digest the message digest to associate with this stream.
*/
public DigestOutputStream(OutputStream stream, MessageDigest digest) {
super(stream);
setMessageDigest(digest);
}
Returns the message digest associated with this stream.
See Also: Returns: the message digest associated with this stream.
/**
* Returns the message digest associated with this stream.
*
* @return the message digest associated with this stream.
* @see #setMessageDigest(java.security.MessageDigest)
*/
public MessageDigest getMessageDigest() {
return digest;
}
Associates the specified message digest with this stream.
Params: - digest – the message digest to be associated with this stream.
See Also:
/**
* Associates the specified message digest with this stream.
*
* @param digest the message digest to be associated with this stream.
* @see #getMessageDigest()
*/
public void setMessageDigest(MessageDigest digest) {
this.digest = digest;
}
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 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. Params: - b – the byte to be used for updating and writing to the
output stream.
Throws: - IOException – if an I/O error occurs.
See Also:
/**
* 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
* {@code update} on the message digest associated with this
* stream, passing it the byte {@code b}. This method then
* writes the byte to the output stream, blocking until the byte
* is actually written.
*
* @param b the byte to be used for updating and writing to the
* output stream.
*
* @exception IOException if an I/O error occurs.
*
* @see MessageDigest#update(byte)
*/
public void write(int b) throws IOException {
out.write(b);
if (on) {
digest.update((byte)b);
}
}
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 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. Params: - 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.
See Also:
/**
* 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 {@code 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.
*
* @param b the array containing the subarray to be used for updating
* and writing to the output stream.
*
* @param off the offset into {@code b} of the first byte to
* be updated and written.
*
* @param len the number of bytes of data to be updated and written
* from {@code b}, starting at offset {@code off}.
*
* @exception IOException if an I/O error occurs.
*
* @see MessageDigest#update(byte[], int, int)
*/
public void write(byte[] b, int off, int len) throws IOException {
out.write(b, off, len);
if (on) {
digest.update(b, off, len);
}
}
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. Params: - on – true to turn the digest function on, false to turn it
off.
/**
* Turns the digest function on or off. The default is on. When
* it is on, a call to one of the {@code write} methods results in an
* update on the message digest. But when it is off, the message
* digest is not updated.
*
* @param on true to turn the digest function on, false to turn it
* off.
*/
public void on(boolean on) {
this.on = on;
}
Prints a string representation of this digest output stream and
its associated message digest object.
/**
* Prints a string representation of this digest output stream and
* its associated message digest object.
*/
public String toString() {
return "[Digest Output Stream] " + digest.toString();
}
}