Class java.security.DigestOutputStream 
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Class java.security.DigestOutputStream 

Object
   |
   +----OutputStream
           |
           +----FilterOutputStream
                   |
                   +----java.security.DigestOutputStream
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 write methods.

It is possible to turn this stream on or off (see on). When it is on, a call to write 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.

Version:
1.20 98/10/05
See Also:
MessageDigest, DigestInputStream

Variable Index

o digest
The message digest associated with this stream.

Constructor Index

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

Method Index

o getMessageDigest()
Returns the message digest associated with this stream.
o on(boolean)
Turns the digest function on or off.
o setMessageDigest(MessageDigest)
Associates the specified message digest with this stream.
o toString()
Prints a string representation of this digest output stream and its associated message digest object.
o write(int)
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.
o write(byte[], int, int)
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.

Variables

o digest 
protected java.security.MessageDigest digest
The message digest associated with this stream.

Constructors

o 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.

Methods

o getMessageDigest 
public java.security.MessageDigest getMessageDigest()
Returns the message digest associated with this stream.

Returns:
the message digest associated with this stream.
o on 
public void on(boolean on)
Turns the digest function on or off. The default is on. When it is on, a call to write 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.
o 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.
o 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 Object
o 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 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.

Parameters:
b - the byte to be used for updating and writing to the output stream.
Throws: IOException
if an I/O error occurs.
Overrides:
write in class FilterOutputStream
See Also:
update(byte)
o 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 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.

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.
Overrides:
write in class FilterOutputStream
See Also:
update(byte[], int, int) 
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