Extract File With CRC32 Checksum Example

/*
	Extract File With CRC32 Checksum Example
	This Java example shows how to extract zip file with CRC32 Checksum
	using CheckedInputStream and CRC32 classes.
*/
 
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.zip.CRC32;
import java.util.zip.CheckedInputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;
 
public class ExtractZipWithCRC32Checksum {
 
	public static void main(String args[])
	{
 
		String sourceZipFile = "C:/FileIO/sourceFile.zip";
 
		try
		{
			//create FileInputStream from the source zip file
			FileInputStream fin = new FileInputStream(sourceZipFile);
 
			/*
			 * To extract zip file with CRC32 checksum, use
			 * 
			 * CheckedInputStream(InputStream in, Checksum checksum)
			 * 
			 * Constructor.
			 */
 
			 //create CheckedInputStream object.
			 CheckedInputStream checksum = new CheckedInputStream(fin,new CRC32());
 
			//create ZipInputStream from CheckedInputStream object
			ZipInputStream zin = new ZipInputStream(checksum);
 
			//get the first entry from the source zip file
			ZipEntry entry = zin.getNextEntry();
 
			//crate OutputStream to extract the entry from zip file
			OutputStream os = new FileOutputStream("c:/extractedFile.css");
 
 
			byte[] buffer = new byte[1024];
			int length;
 
			//read the entry from zip file and extract it to disk
			while( (length = zin.read(buffer)) > 0)
			{
				os.write(buffer, 0, length);
			}
 
			//close the streams
			os.close();
 
			//close the zip file
			zin.close();
 
			System.out.println("File Extracted from zip file");
 
			/*
			 * To get the CRC32 checksum of the extracted file, use
			 * 
			 * Checksum getChecksum()
			 * 
			 * Method of CheckedInputStream class.
			 */
 
			 System.out.println("CRC32 checksum is: " + checksum.getChecksum().getValue());
 
		}
		catch(IOException e)
		{
			System.out.println("IOException :" + e);
		}
 
	}
 
}
 
/*
Output of this example would be
File Extracted from zip file
CRC32 checksum is: 2920622546
*/