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Class java.security.DigestInputStream 

java.lang.Object
   |
   +----java.io.InputStream
           |
           +----java.io.FilterInputStream
                   |
                   +----java.security.DigestInputStream
public class DigestInputStream
extends FilterInputStream
A transparent stream that updates the associated message digest using the bits going through the stream.

To complete the message digest computation, call the digest method on the associated message digest after your calls to the digest input stream's read method.

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

Note that digest objects can compute only one digest (see MessageDigest), so that in order to compute intermediate digests, a caller should retain a handle onto the digest object, and clone it for each digest to be computed, leaving the orginal digest untouched.

See Also:
MessageDigest

Variable Index

o digest
The message digest associated with this stream.

Constructor Index

o DigestInputStream(InputStream, MessageDigest)
Creates a digest input stream, using the specified input 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 read()
Reads a byte, and updates the message digest (if the digest function is on).
o setMessageDigest(MessageDigest)
Associates the specified message digest with this stream.
o toString()
Prints a user-readable representation of the stream.

Variables

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

Constructors

o DigestInputStream 
  public DigestInputStream(InputStream stream,
                           MessageDigest digest)
Creates a digest input stream, using the specified input stream and message digest.

Parameters:
stream - the input stream.
digest - the message digest to associate with this stream.

Methods

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

Returns:
the message digest associated with this stream.
o setMessageDigest 
  public void setMessageDigest(MessageDigest digest)
Associates the specified message digest with this stream.

Parameters:
md - the message digest to be associated with this stream.
o read 
  public int read() throws IOException
Reads a byte, and updates the message digest (if the digest function is on). That is, this method reads a byte from the input stream, blocking until the byte is actually read. If the digest function is on (see on), this method will then call update on the message digest associated with this stream, passing it the byte read.

Returns:
the byte read.
Throws: IOException
if an I/O error occurs.
Overrides:
read in class FilterInputStream
See Also:
update
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 read 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 toString 
  public String toString()
Prints a user-readable representation of the stream.

Overrides:
toString in class Object 
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