code: public static String base64Encode(String rawStr,String encoding) throws IOException{
  		byte [] rawByte = rawStr.getBytes(encoding);
  		return new String(SecureUtil.base64Encode(rawByte),encoding);
  	}
docs: 对字符串做base64<br>
  @param rawStr<br>
  @param encoding<br>
  @return<br>
  @throws IOException