AS3 Base64

//============================================================================
// Base64 
// 通用的base64转byteArray;
//============================================================================

internal class Base64 extends ByteArray {
	private static  const BASE64:Array = [0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,62,0,0,0,63,52,53,54,55,56,57,58,59,60,61,0,0,0,0,0,0,0,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,0,0,0,0,0,0,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,0,0,0,0,0];
	public function Base64(str:String):void {
		var n:int, j:int;
		for (var i:int = 0; i < str.length && str.charAt(i) != "="; i++) {
			j = (j = 8) {
				writeByte((j >> (n -= 8)) & 0xFF);
			}
		}
		position = 0;
	}
}