GWT Base64 Decoding into Binary (supports Unsigned byte data)

This class is a base64 decoder for GWT it could decode base64 string even if it contains unsigned byte data .

package com.project.logic;
//By saher hassan 
public class Base64Decode {
	private final static String base64chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

	public static byte[] decode(String s) {

		// remove/ignore any characters not in the base64 characters list
		// or the pad character -- particularly newlines
		s = s.replaceAll("[^" + base64chars + "=]", "");

		// replace any incoming padding with a zero pad (the 'A' character is
		// zero)
		String p = (s.charAt(s.length() - 1) == '=' ? (s.charAt(s.length() - 2) == '=' ? "AA"
				: "A")
				: "");

		s = s.substring(0, s.length() - p.length()) + p;
		int resLength = (int) Math.ceil(((float) (s.length()) / 4f) * 3f);
		byte[] bufIn = new byte[resLength];
		int bufIn_i = 0;

		// increment over the length of this encrypted string, four characters
		// at a time
		for (int c = 0; c < s.length(); c += 4) {

			// each of these four characters represents a 6-bit index in the
			// base64 characters list which, when concatenated, will give the
			// 24-bit number for the original 3 characters
			int n = (base64chars.indexOf(s.charAt(c)) << 18)
					+ (base64chars.indexOf(s.charAt(c + 1)) << 12)
					+ (base64chars.indexOf(s.charAt(c + 2)) << 6)
					+ base64chars.indexOf(s.charAt(c + 3));

			// split the 24-bit number into the original three 8-bit (ASCII)
			// characters

			char c1 = (char) ((n >>> 16) & 0xFF);
			char c2 = (char) ((n >>>8) & 0xFF);
			char c3 = (char) (n & 0xFF);

			bufIn[bufIn_i++] = (byte) c1;
			bufIn[bufIn_i++] = (byte) c2;
			bufIn[bufIn_i++] = (byte) c3;

		}

		return bufIn;
	}
}

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