Package org.apache.commons.io.input

Class MessageDigestCalculatingInputStream

java.lang.Object

java.io.InputStream

java.io.FilterInputStream

org.apache.commons.io.input.ProxyInputStream

org.apache.commons.io.input.ObservableInputStream

org.apache.commons.io.input.MessageDigestCalculatingInputStream

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class MessageDigestCalculatingInputStream
extends ObservableInputStream

This class is an example for using an ObservableInputStream. It creates its own ObservableInputStream.Observer, which calculates a checksum using a MessageDigest, for example an MD5 sum. Note: Neither ObservableInputStream, nor MessageDigest, are thread safe. So is MessageDigestCalculatingInputStream.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	MessageDigestCalculatingInputStream.MessageDigestMaintainingObserver	Maintains the message digest.

Nested classes/interfaces inherited from class org.apache.commons.io.input.ObservableInputStream

ObservableInputStream.Observer

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

Constructors

Constructor	Description
MessageDigestCalculatingInputStream(java.io.InputStream inputStream)	Creates a new instance, which calculates a signature on the given stream, using a MessageDigest with the "MD5" algorithm.
MessageDigestCalculatingInputStream(java.io.InputStream inputStream, java.lang.String algorithm)	Creates a new instance, which calculates a signature on the given stream, using a MessageDigest with the given algorithm.
MessageDigestCalculatingInputStream(java.io.InputStream inputStream, java.security.MessageDigest messageDigest)	Creates a new instance, which calculates a signature on the given stream, using the given MessageDigest.

Method Summary

Modifier and Type	Method	Description
java.security.MessageDigest	getMessageDigest()	Returns the MessageDigest, which is being used for generating the checksum.

Methods inherited from class org.apache.commons.io.input.ObservableInputStream

add, close, consume, getObservers, noteClosed, noteDataByte, noteDataBytes, noteError, noteFinished, read, read, read, remove, removeAllObservers

Methods inherited from class org.apache.commons.io.input.ProxyInputStream

afterRead, available, beforeRead, handleIOException, mark, markSupported, reset, skip

Methods inherited from class java.io.InputStream

nullInputStream, readAllBytes, readNBytes, readNBytes, transferTo

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MessageDigestCalculatingInputStream

public MessageDigestCalculatingInputStream(java.io.InputStream inputStream,
                                           java.security.MessageDigest messageDigest)

Creates a new instance, which calculates a signature on the given stream, using the given MessageDigest.

Parameters:

inputStream - the stream to calculate the message digest for

messageDigest - the message digest to use

MessageDigestCalculatingInputStream

public MessageDigestCalculatingInputStream(java.io.InputStream inputStream,
                                           java.lang.String algorithm)
                                    throws java.security.NoSuchAlgorithmException

Creates a new instance, which calculates a signature on the given stream, using a MessageDigest with the given algorithm.

Parameters:

inputStream - the stream to calculate the message digest for

algorithm - the name of the algorithm to use

Throws:

java.security.NoSuchAlgorithmException - if no Provider supports a MessageDigestSpi implementation for the specified algorithm.

MessageDigestCalculatingInputStream

public MessageDigestCalculatingInputStream(java.io.InputStream inputStream)
                                    throws java.security.NoSuchAlgorithmException

Creates a new instance, which calculates a signature on the given stream, using a MessageDigest with the "MD5" algorithm.

Parameters:

inputStream - the stream to calculate the message digest for

Throws:

java.security.NoSuchAlgorithmException - if no Provider supports a MessageDigestSpi implementation for the specified algorithm.

Method Detail

getMessageDigest

public java.security.MessageDigest getMessageDigest()

Returns the MessageDigest, which is being used for generating the checksum. Note: The checksum will only reflect the data, which has been read so far. This is probably not, what you expect. Make sure, that the complete data has been read, if that is what you want. The easiest way to do so is by invoking ObservableInputStream.consume().

Returns:

the message digest used