// import java.security.cert.*;
public void readCertificate(File f) throws Exception {
	CertificateFactory cf = CertificateFactory.getInstance("X.509");

	// Use BufferedInputStream (which supports mark and reset) so that each 
	// generateCertificate call consumes one certificate.
	BufferedInputStream in = new BufferedInputStream(new FileInputStream(f));
	while (in.available() > 0) {
	    Certificate cert = cf.generateCertificate(in);
	    System.out.println("Cert:\n===================\n" + cert.toString() + "\n");
	}
	in.close();
}

public void readCertificates(File f) throws Exception {
	CertificateFactory cf = CertificateFactory.getInstance("X.509");

	InputStream in = new FileInputStream(f);
	Collection<?extends Certificate> certs = cf.generateCertificates(in);
	in.close();

	for (Certificate cert: certs) {
	    System.out.println("Cert:\n===================\n" + cert.toString() + "\n");
	}
}