Initial revision

From-SVN: r102074

libjava/classpath/java/security/DigestOutputStream.java

@@ -0,0 +1,158 @@
+/* DigestOutputStream.java --- An output stream tied to a message digest
+   Copyright (C) 1999, 2004, 2005  Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+package java.security;
+
+import java.io.FilterOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+
+/**
+ * DigestOutputStream is a class that ties an OutputStream with a
+ * MessageDigest. The Message Digest is used by the class to update it
+ * self as bytes are written to the OutputStream.
+ *
+ * The updating to the digest depends on the on flag which is set to
+ * true by default that tells the class to update the data in the
+ * message digest.
+ *
+ * @version 0.0
+ * @author Mark Benvenuto (ivymccough@worldnet.att.net)
+ */
+public class DigestOutputStream extends FilterOutputStream
+{
+  /**
+   * The message digest for the DigestOutputStream
+   */
+  protected MessageDigest digest;
+
+  //Manages the on flag
+  private boolean state = true;
+
+  /**
+   * Constructs a new DigestOutputStream.  It associates a
+   * MessageDigest with the stream to compute the stream as data is
+   * written.
+   *
+   * @param stream An OutputStream to associate this stream with
+   * @param digest A MessageDigest to hash the stream with
+   */
+  public DigestOutputStream(OutputStream stream, MessageDigest digest)
+  {
+    super(stream);
+    this.digest = digest;
+  }
+
+  /**
+   * Returns the MessageDigest associated with this DigestOutputStream
+   *
+   * @return The MessageDigest used to hash this stream
+   */
+  public MessageDigest getMessageDigest()
+  {
+    return digest;
+  }
+
+  /**
+   * Sets the current MessageDigest to current parameter
+   *
+   * @param digest A MessageDigest to associate with this stream
+   */
+  public void setMessageDigest(MessageDigest digest)
+  {
+    this.digest = digest;
+  }
+
+
+  /**
+   * Updates the hash if the on flag is true and then writes a byte to
+   * the underlying output stream.
+   *
+   * @param b A byte to write to the output stream
+   *
+   * @exception IOException if the underlying output stream 
+   * cannot write the byte, this is thrown.
+   */
+  public void write(int b) throws IOException
+  {
+    if (state)
+      digest.update((byte) b);
+
+    out.write(b);
+  }
+
+  /**
+   * Updates the hash if the on flag is true and then writes the bytes
+   * to the underlying output stream.
+   *
+   * @param b Bytes to write to the output stream
+   * @param off Offset to start to start at in array
+   * @param len Length of data to write
+   *
+   * @exception IOException if the underlying output stream 
+   * cannot write the bytes, this is thrown.
+   */
+  public void write(byte[]b, int off, int len) throws IOException
+  {
+    if (state)
+      digest.update(b, off, len);
+
+    out.write(b, off, len);
+  }
+
+  /**
+   * Sets the flag specifying if this DigestOutputStream updates the
+   * digest in the write() methods. The default is on;
+   *
+   * @param on True means it digests stream, false means it does not
+   */
+  public void on(boolean on)
+  {
+    state = on;
+  }
+
+  /**
+   * Converts the output stream and underlying message digest to a string.
+   *
+   * @return A string representing the output stream and message digest.
+   */
+  public String toString()
+  {
+    return "[Digest Output Stream] " + digest.toString();
+  }
+}