文件上传（upload）

一、文件上传

public UploadResult upload(MultipartFile file) {
        Assert.notNull(file, "Multipart file must not be null");

        // Get current time  获取当前时间
        Calendar current = Calendar.getInstance(optionService.getLocale());
        // Get month and day of month  获取当前年和月
        int year = current.get(Calendar.YEAR);
        int month = current.get(Calendar.MONTH) + 1;

        String monthString = month < 10 ? "0" + month : String.valueOf(month);

        // Build directory   构建上传文件存储目录
        String subDir = UPLOAD_SUB_DIR + year + FILE_SEPARATOR + monthString + FILE_SEPARATOR;
		//获取上传文件名
        String originalBasename = FilenameUtils.getBasename(Objects.requireNonNull(file.getOriginalFilename()));

        // Get basename	 构建文件名
        String basename = originalBasename + '-' + HaloUtils.randomUUIDWithoutDash();

        // Get extension  构建文件类型
        String extension = FilenameUtils.getExtension(file.getOriginalFilename());

        log.debug("Base name: [{}], extension: [{}] of original filename: [{}]", basename, extension, file.getOriginalFilename());

        // Build sub file path  构建子文件路径
        String subFilePath = subDir + basename + '.' + extension;

        // Get upload path  构建上传文件存储目录路径
        Path uploadPath = Paths.get(workDir, subFilePath);

        log.info("Uploading file: [{}]to directory: [{}]", file.getOriginalFilename(), uploadPath.toString());

        try {
            // TODO Synchronize here
            // Create directory   创建目录，创建文件
            Files.createDirectories(uploadPath.getParent());
            Files.createFile(uploadPath);   

            // Upload this file   上传文件
            file.transferTo(uploadPath);

            // Build upload result   构建上传结果
            UploadResult uploadResult = new UploadResult();
            uploadResult.setFilename(originalBasename);
            uploadResult.setFilePath(subFilePath);
            uploadResult.setKey(subFilePath);
            uploadResult.setSuffix(extension);
            uploadResult.setMediaType(MediaType.valueOf(Objects.requireNonNull(file.getContentType())));
            uploadResult.setSize(file.getSize());

            // TODO refactor this: if image is svg ext. extension
            boolean isSvg = "svg".equals(extension);

            // Check file type  检查文件类型
            if (FileHandler.isImageType(uploadResult.getMediaType()) && !isSvg) {
                lock.lock();
                try (InputStream uploadFileInputStream = new FileInputStream(uploadPath.toFile())) {
                    // Upload a thumbnail   上传压缩图
                    String thumbnailBasename = basename + THUMBNAIL_SUFFIX;
                    String thumbnailSubFilePath = subDir + thumbnailBasename + '.' + extension;
                    Path thumbnailPath = Paths.get(workDir + thumbnailSubFilePath);

                    // Read as image   解读为图像
                    BufferedImage originalImage = ImageUtils.getImageFromFile(uploadFileInputStream, extension);
                    // Set width and height
                    uploadResult.setWidth(originalImage.getWidth());
                    uploadResult.setHeight(originalImage.getHeight());

                    // Generate thumbnail    生成缩略图
                    boolean result = generateThumbnail(originalImage, thumbnailPath, extension);
                    if (result) {
                        // Set thumb path   设置缩略图路径
                        uploadResult.setThumbPath(thumbnailSubFilePath);
                    } else {
                        // If generate error
                        uploadResult.setThumbPath(subFilePath);
                    }
                } finally {
                    lock.unlock();
                }
            } else {
                uploadResult.setThumbPath(subFilePath);
            }

            log.info("Uploaded file: [{}] to directory: [{}] successfully", file.getOriginalFilename(), uploadPath.toString());
            return uploadResult;
        } catch (IOException e) {
            throw new FileOperationException("上传附件失败").setErrorData(uploadPath);
        }
    }

//获取文件名  例如: houtai2.jpg  -->   houtai2
@NonNull
public static String getBasename(@NonNull String filename) {
        Assert.hasText(filename, "Filename must not be blank");

        // Find the last slash
        int separatorLastIndex = StringUtils.lastIndexOf(filename, File.separatorChar);

        if (separatorLastIndex == filename.length() - 1) {
            return StringUtils.EMPTY;
        }

        if (separatorLastIndex >= 0 && separatorLastIndex < filename.length() - 1) {
            filename = filename.substring(separatorLastIndex + 1);
        }

        // Find last dot
        int dotLastIndex = StringUtils.lastIndexOf(filename, '.');

        if (dotLastIndex < 0) {
            return filename;
        }

        return filename.substring(0, dotLastIndex);
    }

@NonNull    //  构建文件的类型  例如： houtai2.jpg  -- > jpg
public static String getExtension(@NonNull String filename) {
        Assert.hasText(filename, "Filename must not be blank");

        // Find the last slash
        int separatorLastIndex = StringUtils.lastIndexOf(filename, File.separatorChar);

        if (separatorLastIndex == filename.length() - 1) {
            return StringUtils.EMPTY;
        }

        if (separatorLastIndex >= 0 && separatorLastIndex < filename.length() - 1) {
            filename = filename.substring(separatorLastIndex + 1);
        }

        // Find last dot
        int dotLastIndex = StringUtils.lastIndexOf(filename, '.');

        if (dotLastIndex < 0) {
            return StringUtils.EMPTY;
        }

        return filename.substring(dotLastIndex + 1);
    }

//返回图像数据缓存区
public static BufferedImage getImageFromFile(InputStream is, String extension) throws IOException {
        log.debug("Current File type is : [{}]", extension);

        if (EXTENSION_ICO.equals(extension)) {
            return ICODecoder.read(is).get(0);
        } else {
            return ImageIO.read(is);
        }
    }