微信小程序上传图片到COS腾讯云

功能需求：用户可以在评论中上传图片，图片保存到腾讯云COS上。

实现方法，微信小程序需要往后台传一个代表文件的参数file代表文件，借助MultipartFile获得文件的路径和文件名等信息。

关键实现代码：

 @RequestMapping(value = "/plugins/fileServer/fileservice/sales/admin", method = RequestMethod.POST)
    void postAdmin(@RequestParam(value = "file", required = false) MultipartFile file, Integer preview_height, Integer preview_width, String target, String type, HttpServletRequest request, HttpServletResponse response) {
        String body = "";
        if (file == null) {
            response.setStatus(401);
            body = GsonUtils.obj2Gson(OutAdmin.error(401, "no file upload")).toString();
            ResponseUtils.renderJson(response, body);
            return;
        }
        if (preview_width == null) {
            preview_width = 128;
        }
        if (preview_height == null) {
            preview_height = 128;
        }
        String uploadPath = "/default";
        if (!StringUtils.isBlank(target)) {
            uploadPath = "/" + target;
        }
        String uploadPreviewPath = uploadPath + "/preview";

        CmsSite site = CmsUtils.getSite(request);
        String fileUrl = upload(site, file, uploadPath);
        if (fileUrl == null) {
            response.setStatus(401);
            body = GsonUtils.obj2Gson(OutAdmin.error(401, "upload error")).toString();
            ResponseUtils.renderJson(response, body);
            return;
        }
        String preview_fileUrl = uploadPreview(site, file, uploadPreviewPath, preview_width, preview_height);
        if (preview_fileUrl == null) {
            response.setStatus(401);
            body = GsonUtils.obj2Gson(OutAdmin.error(401, "upload preview error")).toString();
            ResponseUtils.renderJson(response, body);
            return;
        }

        String content_type = file.getContentType();
        String download_link = fileUrl;
        String fileid = FilenameUtils.getBaseName(fileUrl);
        String filename = FilenameUtils.getName(fileUrl);
        String preview_link = preview_fileUrl;
        Integer result = 0;
        OutAdmin outAdmin = new OutAdmin(content_type, download_link, fileid, filename, preview_link, result);
        body = GsonUtils.obj2Gson(outAdmin).toString();
        ResponseUtils.renderJson(response, body);
    }

    private String upload(CmsSite site, MultipartFile file, String uploadPath) {
        String origName = file.getOriginalFilename();
        Long fileSize = file.getSize() / 1024;//单位KB
        String ext = FilenameUtils.getExtension(origName).toLowerCase(Locale.ENGLISH);
        String fileUrl = null;
        try {
            if (site.getUploadOss() != null) {
                // 支持上传（腾讯）云
                CmsOss oss = site.getUploadOss();
                fileUrl = oss.storeByExt(uploadPath, ext, file.getInputStream());
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return fileUrl;
    }