How do I encode/decode short strings as Base64 using GWT?

Question

I need to encode a short String as base 64 in GWT and decode the base 64 string on the server. Anyone have utility class or library for this?

Answer 1

You can use the BaseEncoding class provided by Guava.

http://docs.guava-libraries.googlecode.com/git/javadoc/com/google/common/io/BaseEncoding.html

For example:

try {
  String encoded = BaseEncoding.base64().encode("foo".getBytes("UTF-8"))
} catch (UnsupportedEncodingException e) {
  GWT.log(e.getMessage());
}

And don't forget to add the following line to your GWT module XML:

<inherits name="com.google.common.io.Io"/>

The BaseEncoding class can be used on both the GWT client side and server side.

Answer 2

Base64 class can't be used on the client side. It would have to be emulated.

Answer 3

You can use native JavaScript for this on the client on all browsers except IE ≤ 9. On the server you can use one of the official classes.

Java/GWT:

private static native String b64decode(String a) /*-{
  return window.atob(a);
}-*/;

Encode is btoa.

Answer 4

You can have a look at https://github.com/mooreds/gwt-crypto

It provides base64 encoding to GWT.

Base64.encode(string.getBytes());

Add the import below :

import com.googlecode.gwt.crypto.bouncycastle.util.encoders.Base64;

Don't forget to add the following line to your GWT module XML:

<inherits name="com.googlecode.gwt.crypto.Crypto"/>    

Maven dependency

<dependency>
    <groupId>com.googlecode.gwt-crypto</groupId>
    <artifactId>gwt-crypto</artifactId>
    <version>2.3.0</version>
</dependency>