java.security

Class DigestInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

java.security.DigestInputStream

All Implemented Interfaces:

Closeable, AutoCloseable

public class DigestInputStream
extends FilterInputStream

DigestInputStream is a FilterInputStream which maintains an associated message digest.

Field Summary

Fields

Modifier and Type	Field and Description
protected MessageDigest	digest The message digest for this stream.

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

Constructors

Constructor and Description
DigestInputStream(InputStream stream, MessageDigest digest) Constructs a new instance of this DigestInputStream, using the given stream and the digest.

Method Summary

Modifier and Type	Method and Description
MessageDigest	getMessageDigest() Returns the message digest for this stream.
void	on(boolean on) Enables or disables the digest function (default is on).
int	read() Reads the next byte and returns it as an int.
int	read(byte[] buffer, int byteOffset, int byteCount) Reads up to byteCount bytes into buffer, starting at byteOffset.
void	setMessageDigest(MessageDigest digest) Sets the message digest which this stream will use.
String	toString() Returns a string containing a concise, human-readable description of this DigestInputStream including the digest.

Methods inherited from class java.io.FilterInputStream

available, close, mark, markSupported, reset, skip

Methods inherited from class java.io.InputStream

nullInputStream, read, readAllBytes, readNBytes, readNBytes, transferTo

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 this stream.

Constructor Detail

DigestInputStream

public DigestInputStream(InputStream stream,
                         MessageDigest digest)

Constructs a new instance of this DigestInputStream, using the given stream and the digest.

Warning: passing a null source creates an invalid DigestInputStream. All operations on such a stream will fail.

Parameters:

stream - the input stream.

digest - the message digest.

Method Detail

getMessageDigest

public MessageDigest getMessageDigest()

Returns the message digest for this stream.

Returns:

the message digest for this stream.

setMessageDigest

public void setMessageDigest(MessageDigest digest)

Sets the message digest which this stream will use.

Parameters:

digest - the message digest which this stream will use.

read

public int read()
         throws IOException

Reads the next byte and returns it as an int. Updates the digest for the byte if this function is on(boolean).

This operation is blocking.

Overrides:

read in class FilterInputStream

Returns:

the byte which was read or -1 at end of stream.

Throws:

IOException - if reading the source stream causes an IOException.

read

public int read(byte[] buffer,
                int byteOffset,
                int byteCount)
         throws IOException

Reads up to byteCount bytes into buffer, starting at byteOffset. Updates the digest if this function is on(boolean).

This operation is blocking.

Returns the number of bytes actually read or -1 if the end of the filtered stream has been reached while reading.

Overrides:

read in class FilterInputStream

Throws:

IOException - if reading the source stream causes an IOException

on

public void on(boolean on)

Enables or disables the digest function (default is on).

Parameters:

on - true if the digest should be computed, false otherwise.

See Also:

MessageDigest

toString

public String toString()

Returns a string containing a concise, human-readable description of this DigestInputStream including the digest.

Overrides:

toString in class Object

Returns:

a printable representation for this DigestInputStream.