Source code: com/flexstor/common/util/Checksum.java

   /*
    * Checksum.java
    *
    * Copyright $Date: 2003/08/11 02:22:31 $ FLEXSTOR.net Inc.
    *
    * This work is licensed for use and distribution under license terms found at
    * http://www.flexstor.org/license.html
    *
    */
  
  package com.flexstor.common.util;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.util.zip.CRC32;
  import java.util.zip.CheckedInputStream;
  
  /**
  *
  *
  */
  public class Checksum
  {
  
      /**
      *
      *
      */
      public Checksum()
      {
      
      } // constructor
      
      
      /**
      *
      *
      */
      public long getChecksum(String sFilename)
      {
          long nResult = -1;
          FileInputStream inStream = null;
          
          // Create a file object and verify that the file can
          // be read
          File refFile = new File(sFilename);
          if ((refFile == null) || (refFile.canRead() == false))
          {
              System.out.println("Cannot open file: " + sFilename);
              return -1;
          }
          
          // Open the file as a normal input stream
          try
          {
              inStream = new FileInputStream(refFile);
          }
          
          catch(FileNotFoundException fnfe)
          {
              System.out.println("Error opening file: " + sFilename + " , fnfe.toString()");
          }
          
          // Create the type of checksum to be used
          CRC32 checksumType = new CRC32();
  //        Adler32 checksumType = new Adler32();
          System.out.println(checksumType.toString());
          
          // Create the checksum input stream
          CheckedInputStream  checkedStream = new CheckedInputStream(inStream, checksumType);
          
          byte[] bData  = new byte[4096];
          int    nCount = 0;
          
          // Dummy read the file
          while (nCount != -1)
          {
              try
              {
                  nCount = checkedStream.read(bData);
              }
              
              catch(IOException ioe)
              {
                  System.out.println("Error reading file: " + sFilename + " , " + ioe.toString());
                  return -1;
              }
          } // while
          
          // File read ok, get the checksum
          nResult = checkedStream.getChecksum().getValue();
  
          return nResult;
      } // getChecksum
      
  } // Checksum class