Decode base64 data in Java

I have an image that is base64 encoded. How do I decode base64 in Java? Hopefully using only the libraries included with Sun Java 6.

As of v6, Java SE ships with JAXB. javax.xml.bind.DatatypeConverter has static methods that make this easy. See parseBase64Binary() and printBase64Binary().

UPDATE: JAXB is no longer shipped with Java (since Java 11). If JAXB is required for your project, you will need to configure the relevant libraries via your dependency management system, for example Maven. If you require the compiler (xjc.exe) you also need to download that separately.

Stack Overflow Q#469695, score: 425