content: package com.twmacinta.util;
  
  import java.io.BufferedInputStream;
  import java.io.FileInputStream;
  import java.io.FilterInputStream;
  import java.io.IOException;
  import java.io.InputStream;
  
  /**
   * MD5InputStream, a subclass of FilterInputStream implementing MD5
   * functionality on a stream.
   * <p/>
   * Originally written by Santeri Paavolainen, Helsinki Finland 1996 <br>
   * (c) Santeri Paavolainen, Helsinki Finland 1996 <br>
   * Some changes Copyright (c) 2002 Timothy W Macinta <br>
   * <p/>
   * This library is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Library General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   * <p/>
   * This library 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
   * Library General Public License for more details.
   * <p/>
   * You should have received a copy of the GNU Library General Public
   * License along with this library; if not, write to the Free
   * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   * <p/>
   * See http://www.twmacinta.com/myjava/fast_md5.php for more information
   * on this file.
   * <p/>
   * Please note: I (Timothy Macinta) have put this code in the
   * com.twmacinta.util package only because it came without a package.  I
   * was not the the original author of the code, although I did
   * optimize it (substantially) and fix some bugs.
   *
   * @author Santeri Paavolainen <santtu@cs.hut.fi>
   * @author Timothy W Macinta (twm@alum.mit.edu) (added main() method)
   **/
  
  
  public class MD5InputStream extends FilterInputStream {
      /**
       * MD5 context
       */
      private MD5 md5;
  
      /**
       * Creates a MD5InputStream
       *
       * @param in The input stream
       */
      public MD5InputStream(InputStream in) {
          super(in);
  
          md5 = new MD5();
      }
  
      /**
       * This method is here for testing purposes only - do not rely
       * on it being here.
       **/
      public static void main(String[] arg) {
          try {
  
              ////////////////////////////////////////////////////////////////
              //
              // usage:  java com.twmacinta.util.MD5InputStream [--use-default-md5] [--no-native-lib] filename
              //
              /////////
  
              // determine the filename to use and the MD5 impelementation to use
  
              String filename = arg[arg.length - 1];
              boolean use_default_md5 = false;
              boolean use_native_lib = true;
              for (int i = 0; i < arg.length - 1; i++) {
                  if (arg[i].equals("--use-default-md5")) {
                      use_default_md5 = true;
                  } else if (arg[i].equals("--no-native-lib")) {
                      use_native_lib = false;
                  }
              }
  
              // initialize common variables
  
              byte[] buf = new byte[65536];
              int num_read;
  
              //   Use the default MD5 implementation that comes with Java
  
              if (use_default_md5) {
                  InputStream in = new BufferedInputStream(new FileInputStream(filename));
                  java.security.MessageDigest digest = java.security.MessageDigest.getInstance("MD5");
                  while ((num_read = in.read(buf)) != -1) {
                      digest.update(buf, 0, num_read);
                  }
                  System.out.println(MD5.asHex(digest.digest()) + "  " + filename);
                  in.close();
  
                  // Use the optimized MD5 implementation
  
              } else {
  
                  //    disable the native library search, if requested
  
                  if (!use_native_lib) {
                      MD5.initNativeLibrary(true);
                  }
  
                  //    calculate the checksum
  
                  MD5InputStream in = new MD5InputStream(new BufferedInputStream(new FileInputStream(filename)));
                  while ((num_read = in.read(buf)) != -1) ;
                  System.out.println(MD5.asHex(in.hash()) + "  " + filename);
                  in.close();
              }
          } catch (Exception e) {
              e.printStackTrace();
          }
      }
  
      /**
       * Read a byte of data.
       *
       * @see java.io.FilterInputStream
       */
      @Override
      public int read() throws IOException {
          int c = in.read();
  
          if (c == -1)
              return -1;
  
          if ((c & ~0xff) != 0) {
              System.out.println("MD5InputStream.read() got character with (c & ~0xff) != 0)!");
          } else {
              md5.Update(c);
          }
  
          return c;
      }
  
      /**
       * Reads into an array of bytes.
       *
       * @see java.io.FilterInputStream
       */
      @Override
      public int read(byte bytes[], int offset, int length) throws IOException {
          int r;
  
          if ((r = in.read(bytes, offset, length)) == -1)
              return r;
  
          md5.Update(bytes, offset, r);
  
          return r;
      }
  
      /**
       * Returns array of bytes representing hash of the stream as
       * finalized for the current state.
       *
       * @see MD5#Final
       */
      public byte[] hash() {
          return md5.Final();
      }
  
      public MD5 getMD5() {
          return md5;
      }
  
  }
  
  