A single checksum calculation for multiple files : Checksum « File « Java Tutorial

Java Tutorial
1. Language
2. Data Type
3. Operators
4. Statement Control
5. Class Definition
6. Development
7. Reflection
8. Regular Expressions
9. Collections
10. Thread
11. File
12. Generics
13. I18N
14. Swing
15. Swing Event
16. 2D Graphics
17. SWT
18. SWT 2D Graphics
19. Network
20. Database
21. Hibernate
22. JPA
23. JSP
24. JSTL
25. Servlet
26. Web Services SOA
27. EJB3
28. Spring
29. PDF
30. Email
31. J2ME
32. J2EE Application
33. XML
34. Design Pattern
35. Log
36. Security
37. Apache Common
38. Ant
39. JUnit
Java
Java Source Code / Java Documentation
Java Open Source
Jar File Download
Java Articles
Java Products
Java by API
Photoshop Tutorials
Maya Tutorials
Flash Tutorials
3ds-Max Tutorials
Illustrator Tutorials
GIMP Tutorials
C# / C Sharp
C# / CSharp Tutorial
C# / CSharp Open Source
ASP.Net
ASP.NET Tutorial
JavaScript DHTML
JavaScript Tutorial
JavaScript Reference
HTML / CSS
HTML CSS Reference
C / ANSI-C
C Tutorial
C++
C++ Tutorial
Ruby
PHP
Python
Python Tutorial
Python Open Source
SQL Server / T-SQL
SQL Server / T-SQL Tutorial
Oracle PL / SQL
Oracle PL/SQL Tutorial
PostgreSQL
SQL / MySQL
MySQL Tutorial
VB.Net
VB.Net Tutorial
Flash / Flex / ActionScript
VBA / Excel / Access / Word
XML
XML Tutorial
Microsoft Office PowerPoint 2007 Tutorial
Microsoft Office Excel 2007 Tutorial
Microsoft Office Word 2007 Tutorial
Java Tutorial » File » Checksum 
11. 69. 1. A single checksum calculation for multiple files
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 
 *      http://www.apache.org/licenses/LICENSE-2.0
 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.zip.Adler32;
import java.util.zip.CheckedInputStream;
import java.util.zip.Checksum;

/**
 * Perform a single checksum calculation for multiple files
 *
 @author <a href="mailto:ate@douma.nu">Ate Douma</a>
 @author <a href="mailto:taylor@apache.org">David Sean Taylor </a>
 @version $Id$
 */
public class MultiFileChecksumHelper
{
    public static long getChecksum(File[] files)
    {
        CheckedInputStream cis = null;
        FileInputStream is = null;
        Checksum checksum = new Adler32();
        byte[] tempBuf = new byte[128];
        
        for int i = 0; i < files.length && files[i!= null && files[i].exists() && files[i].isFile(); i++ )
        {
            try 
            {
                is = new FileInputStream(files[i]);
                cis = new CheckedInputStream(is, checksum);
                while (cis.read(tempBuf>= 0) {}                
            }
            catch (Exception e)
            {
                throw new RuntimeException(e);
            }
            finally
            {
                if (cis != null)
                {
                    try
                    {
                        cis.close();
                    }
                    catch (IOException ioe) {}
                    cis = null;
                }
                if (is != null)
                {
                    try
                    {
                        is.close();
                    }
                    catch (IOException ioe) {}
                    is = null;
                }
            }
        }
        return checksum.getValue();
    }
}
11. 69. Checksum
11. 69. 1. A single checksum calculation for multiple files
11. 69. 2. Compressing Streams: Parity Checksum
11. 69. 3. Compressing Streams: File Summer
11. 69. 4. Calculating the Checksum of a Byte Array (Compute Adler-32 checksum)
11. 69. 5. Compute CRC-32 checksum
11. 69. 6. Calculating the Checksum of a File
11. 69. 7. The java.util.zip package can be used to create a checksum.
11. 69. 8. Check sum for an InputStream
www.java2java.com | Contact Us
Copyright 2009 - 12 Demo Source and Support. All rights reserved.
All other trademarks are property of their respective owners.