code: public static String base64Decode(String base64Str,String encoding) throws IOException{
  		byte [] rawByte = base64Str.getBytes(encoding);
  		return new String(SecureUtil.base64Decode(rawByte),encoding);	
  	}
docs: 对base64的字符串解base64<br>
  @param base64Str<br>
  @param encoding<br>
  @return<br>
  @throws IOException