public static  String byte2HexString(byte[] photo){
		String format = "";
		if (photo != null) {
			for (int i = 0; i < 2; i++) {
				String hex = Integer.toHexString(photo[i] & 0xFF);
				if (hex.length() == 1) {
					hex = '0' + hex;
				}
				format+=hex;
				//System.out.print(hex.toUpperCase());
			}
			//System.out.println(format);
		}
		if(FORMAT_JPEG.equals(format)){
			return "jpeg";
		}else if(FORMAT_PNG.equals(format)){
			return "png";
		}else if(FORMAT_BMP.equals(format)){
			return "bmp";
		}else{
			return "other";
		}
	}