File	Doc	Category	Size	Date	Package
DigestInputStream.java	API Doc	Java SE 5 API	5473	Fri Aug 26 14:57:14 BST 2005	java.security

DigestInputStream

• java.lang.Object
  • java.io.InputStream
    • java.io.FilterInputStream

Fields Summary
private boolean	on
protected MessageDigest	digest The message digest associated with this stream.

Constructors Summary
public DigestInputStream(InputStream stream, MessageDigest digest) Creates a digest input stream, using the specified input stream and message digest. param stream the input stream. param digest the message digest to associate with this stream. super(stream); setMessageDigest(digest);

Methods Summary
public java.security.MessageDigest	getMessageDigest() Returns the message digest associated with this stream. return the message digest associated with this stream. see #setMessageDigest(java.security.MessageDigest) return digest;
public void	on(boolean on) Turns the digest function on or off. The default is on. When it is on, a call to one of the read 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. this.on = on;
public int	read() 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 {@link #on(boolean) on}), this method will then call update on the message digest associated with this stream, passing it the byte read. return the byte read. exception IOException if an I/O error occurs. see MessageDigest#update(byte) int ch = in.read(); if (on && ch != -1) { digest.update((byte)ch); } return ch;
public int	read(byte[] b, int off, int len) Reads into a byte array, and updates the message digest (if the digest function is on). That is, this method reads up to len bytes from the input stream into the array b, starting at offset off. This method blocks until the data is actually read. If the digest function is on (see {@link #on(boolean) on}), this method will then call update on the message digest associated with this stream, passing it the data. param b the array into which the data is read. param off the starting offset into b of where the data should be placed. param len the maximum number of bytes to be read from the input stream into b, starting at offset off. return the actual number of bytes read. This is less than len if the end of the stream is reached prior to reading len bytes. -1 is returned if no bytes were read because the end of the stream had already been reached when the call was made. exception IOException if an I/O error occurs. see MessageDigest#update(byte[], int, int) int result = in.read(b, off, len); if (on && result != -1) { digest.update(b, off, result); } return result;
public void	setMessageDigest(java.security.MessageDigest digest) Associates the specified message digest with this stream. param digest the message digest to be associated with this stream. see #getMessageDigest() this.digest = digest;
public java.lang.String	toString() Prints a string representation of this digest input stream and its associated message digest object. return "[Digest Input Stream] " + digest.toString();