Java
If you’d like an easy way of working with Gravatar, then check out Nathan Cheshire’s GravatarJavaClient, otherwise read on. Things are a little complex in Java. The following class will provide you with a static method that returns the format SHA-256 of an input string:
import java.util.*;
import java.io.*;
import java.security.*;
public class HashUtil {
public static String hex(byte[] array) {
StringBuffer sb = new StringBuffer();
for (int i = 0; i < array.length; ++i) {
sb.append(Integer.toHexString((array[i]
& 0xFF) | 0x100).substring(1,3));
}
return sb.toString();
}
public static String sha256Hex(String message) {
try {
MessageDigest md = MessageDigest.getInstance("SHA-256");
return hex(md.digest(message.getBytes("UTF-8")));
} catch (NoSuchAlgorithmException e) {
// Consider logging this exception or rethrowing as a RuntimeException
} catch (UnsupportedEncodingException e) {
// Consider logging this exception or rethrowing as a RuntimeException
}
return null;
}
}
This class can then be used to return the SHA-256 hash of an email address (make sure you lower case it first!) like this:
String email = "someone@somewhere.com".toLowerCase(); String hash = sha256Hex(email); String gravatarURL = "https://gravatar.com/avatar/" + hash;
With the hex string that is returned, you can construct your gravatar URL.
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