// the base64 encoding - acceptable estimation of encoded size
StringBuilder sb = new StringBuilder(file.length() / 3 * 4);
FileInputStream fin = null;
try {
fin = new FileInputStream("some.file");
// Max size of buffer
int bSize = 3 * 512;
// Buffer
byte[] buf = new byte[bSize];
// Actual size of buffer
int len = 0;
while((len = fin.read(buf)) != -1) {
byte[] encoded = Base64.encodeBase64(buf);
// Although you might want to write the encoded bytes to another
// stream, otherwise you'll run into the same problem again.
sb.append(new String(buf, 0, len));
}
} catch(IOException e) {
if(null != fin) {
fin.close();
}
}
String base64EncodedFile = sb.toString();