Restituire un file dal controller in primavera

Question

Sono nuovo alla primavera. Ho un controller con un RequestMapping per diversi parametri GET. Restituiscono una stringa. Ma un metodo deve restituire un file nella cartella "/ res /". Come lo faccio?

@RequestMapping(method = RequestMethod.GET,value = "/getfile") 
public @ResponseBody 
String getReviewedFile(@RequestParam("fileName") String fileName) 
{ 
    return //the File Content or better the file itself 
} 

Grazie

Answer 1

Grazie a @ JAR.JAR.beans. Ecco il link: Downloading a file from spring controllers

@RequestMapping(value = "/files/{file_name}", method = RequestMethod.GET) 
@ResponseBody 
public FileSystemResource getFile(@PathVariable("file_name") String fileName) { 
    return new FileSystemResource(myService.getFileFor(fileName)); 
} 

Answer 2

Può essere che questo vi aiuterà

@RequestMapping(method = RequestMethod.GET,value = "/getfile") 
public @ResponseBody 
void getReviewedFile(HttpServletRequest request, HttpServletResponse response, @RequestParam("fileName") String fileName) 
{ 
    //do other stuff 
    byte[] file = //get your file from the location and convert it to bytes 
    response.reset(); 
    response.setBufferSize(DEFAULT_BUFFER_SIZE); 
    response.setContentType("image/png"); //or whatever file type you want to send. 
    try { 
     response.getOutputStream().write(image); 
    } catch (IOException e) { 
     // Do something 
    } 
} 

Answer 3

Un altro modo, anche se Jatin's answer è il modo più fresco:

//Created inside the "scope" of @ComponentScan 
@Configuration 
public class AppConfig extends WebMvcConfigurerAdapter { 
    @Value("${files.dir}") 
    private String filesDir; 

    @Override 
    public void addResourceHandlers(ResourceHandlerRegistry registry) { 
     registry 
       .addResourceHandler("/files/**") 
       .addResourceLocations("file:" + filesDir); 
    } 
} 

sollevato da:

• http://www.baeldung.com/spring-mvc-static-resources
• https://spring.io/blog/2014/07/24/spring-framework-4-1-handling-static-web-resources

Answer 4

Questo funziona come un fascino per me:

@RequestMapping(value="/image/{imageId}", method = RequestMethod.GET) 
    public ResponseEntity<byte[]> getImage(@PathVariable String imageId) { 
     RandomAccessFile f = null; 
     try { 
      f = new RandomAccessFile(configs.getImagePath(imageId), "r"); 
      byte[] b = new byte[(int)f.length()]; 
      f.readFully(b); 
      f.close(); 
      final HttpHeaders headers = new HttpHeaders(); 
      headers.setContentType(MediaType.IMAGE_PNG); 
      return new ResponseEntity<byte[]>(b, headers, HttpStatus.CREATED); 
     } catch (Exception e) { 
      return null; 
     } 
    }