Reading Base64-Encoded Certificates

The following example reads a file with Base64-encoded certificates, which are each bounded at the beginning by

-----BEGIN CERTIFICATE-----

and at the end by

-----END CERTIFICATE-----

We convert the FileInputStream (which does not support mark and reset) to a ByteArrayInputStream (which supports those methods), so that each call to generateCertificate consumes only one certificate, and the read position of the input stream is positioned to the next certificate in the file:

FileInputStream fis = new FileInputStream(filename);
DataInputStream dis = new DataInputStream(fis);
CertificateFactory cf = CertificateFactory.getInstance("X.509");
byte[] bytes = new byte[dis.available()];
dis.readFully(bytes);
ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
while (bais.available() > 0) {
	Certificate cert = cf.generateCertificate(bais);
	System.out.println(cert.toString());
}