Java 9
Use the Java 8 solution. Note DatatypeConverter can still be used, but it is now within the java.xml.bind module which will need to be included.
module org.example.foo {
requires java.xml.bind;
}
Java 8
Java 8 now provides java.util.Base64 for encoding and decoding base64.
Encoding
byte[] message = "hello world".getBytes(StandardCharsets.UTF_8);
String encoded = Base64.getEncoder().encodeToString(message);
System.out.println(encoded);
// => aGVsbG8gd29ybGQ=
Decoding
byte[] decoded = Base64.getDecoder().decode("aGVsbG8gd29ybGQ=");
System.out.println(new String(decoded, StandardCharsets.UTF_8));
// => hello world
Java 6 and 7
Since Java 6 the lesser known class javax.xml.bind.DatatypeConverter can be used. This is part of the JRE, no extra libraries required.
Encoding
byte[] message = "hello world".getBytes("UTF-8");
String encoded = DatatypeConverter.printBase64Binary(message);
System.out.println(encoded);
// => aGVsbG8gd29ybGQ=
Decoding
byte[] decoded = DatatypeConverter.parseBase64Binary("aGVsbG8gd29ybGQ=");
System.out.println(new String(decoded, "UTF-8"));
// => hello world
