public class FileUtil {
    @Value("${img.url}")
    public String imgUrl;
    @Value("${video.url}")
    public String videoUrl;

    /**
     * 儲存圖片
     * @param files 圖片流
     * @return
     */
    public String saveImg(MultipartFile[] files) {
        StringBuilder builder = new StringBuilder();
        for (MultipartFile file : files) {
            //獲取檔名稱
            String fileName = file.getOriginalFilename();
            //生成新檔名稱
            String newFileName = UUID.randomUUID() + fileName.substring(fileName.indexOf("."));
            File startUrl = new File(imgUrl);
            //建立資料夾
            if (!startUrl.exists()) {
                startUrl.mkdirs();
            }
            //生成檔案
            File fileSave = new File(imgUrl + newFileName);
            //儲存檔案
            try {
                file.transferTo(fileSave);
                builder.append("," + newFileName);
            } catch (IOException e) {
                e.printStackTrace();
                return "error";
            }
        }
        return builder.toString();
    }

    /**
     * 儲存視訊
     * @param file 視訊流
     * @return
     */
    public String saveVideo(MultipartFile file) {
        //獲取檔名稱
        String fileName = file.getOriginalFilename();
        //生成新檔名稱
        String newFileName = UUID.randomUUID() + fileName.substring(fileName.indexOf("."));
        File startUrl = new File(videoUrl);
        //建立資料夾
        if (!startUrl.exists()) {
            startUrl.mkdirs();
        }
        //生成檔案
        File fileSave = new File(videoUrl + newFileName);
        //儲存檔案
        try {
            file.transferTo(fileSave);
        } catch (IOException e) {
            e.printStackTrace();
            return "error";
        }
        return newFileName;
    }

    /**
     * 刪除視訊
     * @param name
     * @return
     */
    public void deletFile(String name) {
        File file = new File(videoUrl + name);
        if (file.exists()) {
            file.delete();
        }
    }

    /**
     * 刪除圖片
     * @param name
     * @return
     */
    public void deletFiles(String name) {
        File file = new File(imgUrl + name);
        if (file.exists()) {
            file.delete();
        }
    }

    /**
     * 擷取視訊的幀，形成視訊的預覽圖片
     *
     * @param videoName 視訊名
     */
    public String cutPhotoFromVedio(String videoName) {
        FFmpegFrameGrabber ff = null;
        String videoPath = videoUrl + videoName;
        String imgPath = videoUrl + videoName.substring(0, videoName.lastIndexOf(".")) + ".jpg";
        String newImgName = videoName.substring(0, videoName.lastIndexOf(".")) + ".jpg";
        File targetFile = new File(imgPath);
        try {
            ff = new FFmpegFrameGrabber(videoPath);
            ff.start();
            int lenght = ff.getLengthInFrames();
            int i = 0;
            Frame f = null;
            while (i < lenght) {
                // 過濾前5幀，避免出現全黑的圖片，依自己情況而定
                f = ff.grabFrame();
                if ((i > 5) && (f.image != null)) {
                    break;
                }
                i++;
            }
            opencv_core.IplImage img = f.image;
            int owidth = img.width();
            int oheight = img.height();
            // 對擷取的幀進行等比例縮放
            int width = 800;
            int height = (int) (((double) width / owidth) * oheight);
            BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);
            bi.getGraphics().drawImage(f.image.getBufferedImage().getScaledInstance(width, height, Image.SCALE_SMOOTH),
                    0, 0, null);
            ImageIO.write(bi, "jpg", targetFile);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (ff != null) {
                    ff.stop();
                }
            } catch (FrameGrabber.Exception e) {
                e.printStackTrace();
            }
        }
        return newImgName;
    }
}

/**
　*　　檔案下載

　*　　fileName 檔名稱

*/

public Response download(HttpServletResponse response, String fileName) {
    if (fileName != null) {
        File file = new File(filePath, fileName);
        if (file.exists()) {
            response.reset();
            response.setContentType("application/octet-stream; charset=utf-8");
            try {
                response.setHeader("Content-Disposition", "attachment;" +
                        "filename=" + new String(fileName.getBytes("UTF8"), "ISO8859-1"));
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
            byte[] b = new byte[1024];
            FileInputStream fis = null;
            BufferedInputStream bis = null;
            try {
                fis = new FileInputStream(file);
                bis = new BufferedInputStream(fis);
                OutputStream os = response.getOutputStream();
                int i = bis.read(b);
                while (i != -1) {
                    os.write(b, 0, i);
                    i = bis.read(b);
                }
                return new Response().success("檔案下載成功！");
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                if (bis != null) {
                    try {
                        bis.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                if (fis != null) {
                    try {
                        fis.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }
    return new Response().success();
}

/**
　*　　IO讀取視訊或圖片

　*　　videoName 檔名稱

*/

public void getVideo(String videoName, HttpServletResponse response) throws IOException {
    response.setContentType("images/*;charset=UTF-8");
    ServletOutputStream out = null;
    FileInputStream ips = null;
    String filePath = videoUrl + videoName;
    try {
        File file = new File(filePath);
        if (file.exists()) {
            ips = new FileInputStream(new File(filePath));
            out = response.getOutputStream();
            int len = 0;
            byte[] buffer = new byte[1024 * 10];
            while ((len = ips.read(buffer)) != -1) {
                out.write(buffer, 0, len);
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (!StringUtils.isEmpty(out)) {
            out.flush();
            out.close();
            ips.close();
        }

    }
}