把文件转化为byte[],java

    /**     * 把一个文件转化为字节     *     * @param file     * @return byte[]     * @throws Exception     */    public static byte[] getByte(File file) throws Exception {        byte[] bytes = null;        if (file != null) {            InputStream is = new FileInputStream(file);            int length = (int) file.length();            if (length > Integer.MAX_VALUE)   //当文件的长度超过了int的最大值            {                System.out.println("this file is max ");                return null;            }            bytes = new byte[length];            int offset = 0;            int numRead = 0;            while (offset < bytes.length && (numRead = is.read(bytes, offset, bytes.length - offset)) >= 0) {                offset += numRead;            }            //如果得到的字节长度和file实际的长度不一致就可能出错了            if (offset < bytes.length) {                System.out.println("file length is error");                return null;            }            is.close();        }        return bytes;    }