How do I convert a byte array to Base64 in Java?

Question

Okay, I know how to do it in C#.

It's as simple as:

Convert.ToBase64String(byte[])
and Convert.FromBase64String(string) to get byte[] back.

How can I do this in Java?

Tisdale

Answer 1

Java 8+

Encode or decode byte arrays:

byte[] encoded = Base64.getEncoder().encode("Hello".getBytes());
println(new String(encoded));   // Outputs "SGVsbG8="

byte[] decoded = Base64.getDecoder().decode(encoded);
println(new String(decoded))    // Outputs "Hello"

Or if you just want the strings:

String encoded = Base64.getEncoder().encodeToString("Hello".getBytes());
println(encoded);   // Outputs "SGVsbG8="

String decoded = new String(Base64.getDecoder().decode(encoded.getBytes()));
println(decoded)    // Outputs "Hello"

For more info, see Base64.

Java < 8

Base64 is not bundled with Java versions less than 8. I recommend using Apache Commons Codec.

For direct byte arrays:

Base64 codec = new Base64();
byte[] encoded = codec.encode("Hello".getBytes());
println(new String(encoded));   // Outputs "SGVsbG8="

byte[] decoded = codec.decode(encoded);
println(new String(decoded))    // Outputs "Hello"

Or if you just want the strings:

Base64 codec = new Base64();
String encoded = codec.encodeBase64String("Hello".getBytes());
println(encoded);   // Outputs "SGVsbG8="

String decoded = new String(codec.decodeBase64(encoded));
println(decoded)    // Outputs "Hello"

Android (with Java < 8)

If you are using the Android SDK before Java 8 then your best option is to use the bundled android.util.Base64.

For direct byte arrays:

byte[] encoded = Base64.encode("Hello".getBytes());
println(new String(encoded))    // Outputs "SGVsbG8="

byte [] decoded = Base64.decode(encoded);
println(new String(decoded))    // Outputs "Hello"

Or if you just want the strings:

String encoded = Base64.encodeToString("Hello".getBytes());
println(encoded);   // Outputs "SGVsbG8="

String decoded = new String(Base64.decode(encoded));
println(decoded)    // Outputs "Hello"

Other: Spring < 6.0.5

_{If for some reason Java's Base64 isn't suitable and you use Spring, see Base64Utils. This package, however, is deprecated as of 6.0.5 and so I don't recommend.}

Desirous

On Android, the encode and encodeToString methods also expect a flags parameter, so you need to do Base64.encode("Hello".getBytes(), Base64.DEFAULT); (and the same for encodeToString). – Callimachus

great answer, in my opinion must be accepted as correct answer. – Nazarius

Base64Utils is now deprecated since Spring 6.0.5 (and is scheduled for removal in incoming 6.2 version) in favor of java.util.Base64. – Bots

Answer 2

Use:

byte[] data = Base64.encode(base64str);

Encoding converts to Base64

You would need to reference commons codec from your project in order for that code to work.

For java8:

import java.util.Base64

Bellaude

The methods for encode / decode of class Base64 are static so you don't need to create a new object. Then: byte [] data = Base64.decode(base64str); is enough. – Acquaint

Answer 3

Additionally, for our Android friends (API Level 8):

import android.util.Base64

...

Base64.encodeToString(bytes, Base64.DEFAULT);

Mayce

Answer 4

In case you happen to be using Spring framework along with java, there is an easy way around.

1. Import the following.

   import org.springframework.util.Base64Utils;

2. Convert like this.

   byte[] bytearr ={0,1,2,3,4};
   String encodedText = Base64Utils.encodeToString(bytearr);
   

   To decode you can use the decodeToString method of the Base64Utils class.

Astrix