从 Spring 加载图像/文件 启动 Rest api 到 Android 前端

Question

This is my controller end point that will take the request from the frontend with the filename and using that filename image/file shall be returned. It works fine while testing on postman but I have no idea how to load images/files from this end point in android.

GetMapping("downloadFile/{fileName}")
    @PreAuthorize("hasRole('ADMIN') or hasRole('MODERATOR') or hasRole('USER')")
    public ResponseEntity<Resource> downloadFile(@PathVariable String fileName, HttpServletRequest request) {
        Resource resource = fileStorageService.loadFileAsResource(fileName);
        //System.out.println(resource);
        String contentType = null;
        try {
            contentType = request.getServletContext().getMimeType(resource.getFile().getAbsolutePath());
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        if (contentType == null) {
            contentType = AppConstants.DEFAULT_CONTENT_TYPE;
        }
        return ResponseEntity.ok().contentType(MediaType.parseMediaType(contentType))
                .header(HttpHeaders.CONTENT_DISPOSITION,
                        String.format(AppConstants.FILE_DOWNLOAD_HTTP_HEADER, resource.getFilename()))
                .body(resource);
    }

And My service for this looks like..

 public Resource loadFileAsResource(String fileName) {
            try {
                //Path filePath = this.fileStorageLocation.resolve(fileName).normalize();
                Path filePath= this.fileStoragePath.resolve(fileName).normalize();

                Resource resource = new UrlResource(filePath.toUri());

                if (resource.exists()) {
                    
                    return resource;
                } else {
                    throw new FileStorageException(AppConstants.FILE_NOT_FOUND + fileName);
                }
            } catch (MalformedURLException ex) {
                throw new FileStorageException(AppConstants.FILE_NOT_FOUND + fileName, ex);
            }
            
        }

I need to load image/files from here to the android frontend.

Answer 1

Picasso is the option to do this. just load your images with the resource you receive from server...