Android 根据FFD8 FFD9获取图片

 byte数组中包含jpeg数据，以FFD8开始、FFD9结束，查找标记位置，转换bitmap

    private byte[] tagStartBytes = hexStringToBytes("FFD8");
    private byte[] tagEndBytes = hexStringToBytes("FFD9");

    private Bitmap getBitmap(byte[] originBytes) {
        int startIndex = 0;
        int endIndex = 0;
        for (int i = 0; i <= originBytes.length - 2; i++) {
            if (startIndex == 0) {
                if (originBytes[i] == tagStartBytes[0]) {
                    if (originBytes[i + 1] == tagStartBytes[1]) {
                        startIndex = i;
                    }
                }
            }
            if (startIndex == 0) {
                continue;
            }
            if (originBytes[i] == tagEndBytes[0]) {
                if (originBytes[i + 1] == tagEndBytes[1]) {
                    endIndex = i;
                    break;
                }
            }
        }
        if (startIndex > 0 && endIndex > 0 && endIndex > startIndex) {
            //16进制字符占4位，byte 8位
            int length = endIndex + 1 - startIndex + 1;
            return BitmapFactory.decodeByteArray(originBytes, startIndex, length);
        }
        return null;
    }

    public static byte[] hexStringToBytes(String hexString) {
        if (hexString == null || hexString.equals("")) {
            return null;
        }
        hexString = hexString.toUpperCase();
        int length = hexString.length() / 2;
        char[] hexChars = hexString.toCharArray();
        byte[] d = new byte[length];
        for (int i = 0; i < length; i++) {
            int pos = i * 2;
            d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos +         1]));
        }
        return d;
    }

不足之处，欢迎指正