Java byte[]转换为int

    public static int byte2int(byte[] data, int n) {
        switch (n) {
            case 1:
                return (int) data[0];
            case 2:
                return (int) (((data[1] & 0xff)<<8) | ((data[0] & 0xff00)));
            case 3:
                return  ((data[2] & 0xff)<<16)|
                        ((data[1] & 0xff)<<8)|
                        (data[0] & 0xff);
            case 4:
                return (int) (((data[3] & 0xff) << 24 ) | ((data[2] & 0xff00) << 16) | ((data[1] & 0xff0000) << 8)
                        | ((data[0] & 0xff000000)));
            default:
                return 0;
        }
    }