Construct secure networked applications with certificates, Part 3

import java.io.FileInputStream;
import java.util.Set;
import java.util.Iterator;
import java.security.cert.CertificateFactory;
import java.security.cert.X509CRL;
import java.security.cert.X509CRLEntry;
public
class Main
{
  public
  static
  void
  main(String [] arstring)
  {
    try
    {
      // Get the correct certificate factory.
      CertificateFactory certificatefactory =
        CertificateFactory.getInstance("X.509");
      // Each file specified on the command line must contain a single
      // DER-encoded X.509 CRL.
      for (int i = 0; i < arstring.length; i++)
      {
        // Open the file.
        FileInputStream fileinputstream = new FileInputStream(arstring[i]);
        // Generate a certificate from the data in the file.
        X509CRL x509crl =
          (X509CRL)certificatefactory.generateCRL(fileinputstream);
        // Print out information about the crl.
        System.out.println("---CRL---");
        System.out.println("type = " +
          x509crl.getType());
        System.out.println("version = " +
          x509crl.getVersion());
        System.out.println("issuer = " +
          x509crl.getIssuerDN().getName());
        System.out.println("signing algorithm = " +
          x509crl.getSigAlgName());
        System.out.println("signing OID = " +
          x509crl.getSigAlgOID());
        System.out.println("this update = " +
          x509crl.getThisUpdate());
        System.out.println("next update = " +
          x509crl.getNextUpdate());
        System.out.println();
        // Next, let's print out information about the entries.
        System.out.println("---Entries---");
        Set setEntries = x509crl.getRevokedCertificates();
        if (setEntries != null && setEntries.isEmpty() == false)
        {
          for (Iterator iterator = setEntries.iterator();
               iterator.hasNext(); )
          {
            X509CRLEntry x509crlentry = (X509CRLEntry)iterator.next();
            System.out.println("serial number = " +
              x509crlentry.getSerialNumber());
            System.out.println("revocation date = " +
              x509crlentry.getRevocationDate());
            System.out.println("extensions = " +
              x509crlentry.hasExtensions());
            System.out.println();
          }
        }
        // We're done.
        System.out.println("---");
        // Close the file.
        fileinputstream.close();
      }
    }
    catch (Exception exception)
    {
      exception.printStackTrace();
    }
  }
}