将文件转成byte[]文件属组

/**
     *
     *  @Description    : 读取文件数组
     *  @Method_Name    : fileBuff
     *  @param filePath
     *  @return
     *  @throws IOException
     *  @return         : byte[]
     *  @Creation Date  : 2015年1月27日 下午5:26:49
     *  @Author         :
     */
    public static byte[] fileBuff(String filePath) throws IOException {
        File file = new File(filePath);
        long fileSize = file.length();
        if (fileSize > Integer.MAX_VALUE) {
            //System.out.println("file too big...");
            return null;
        }
        FileInputStream fi = new FileInputStream(file);
        byte[] file_buff = new byte[(int) fileSize];
        int offset = 0;
        int numRead = 0;
        while (offset < file_buff.length && (numRead = fi.read(file_buff, offset, file_buff.length - offset)) >= 0) {
            offset += numRead;
        }
        // 确保所有数据均被读取
        if (offset != file_buff.length) {
        throw new IOException("Could not completely read file "
                    + file.getName());
        }
        fi.close();
        return file_buff;
    }