Which Java library provides base64 encoding/decoding? [duplicate]

I am wondering which library to use for base64 encoding/decoding? I need this functionality be stable enough for production use.

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

Within Apache Commons, commons-codec-1.7.jar contains a Base64 class which can be used to encode.

Via Maven:

<dependency>
    <groupId>commons-codec</groupId>
    <artifactId>commons-codec</artifactId>
    <version>20041127.091804</version>
</dependency>

Direct Download

If you're an Android developer you can use android.util.Base64 class for this purpose.

Guava also has Base64 (among other encodings and incredibly useful stuff)