download a file from Spring boot rest service

Question

I am trying to download a file from a Spring boot rest service    RequestMapping path   downloadFile  method RequestMethod GET       Consumes MediaType APPLICATION JSON VALUE      public  ResponseEntity lt InputStreamReader gt  downloadDocument                  String acquistionId                  String fileType                  Integer expressVfId  throws IOException           File file2Upload   new File  C   Users  admin  Desktop  bkp  1 rtf            HttpHeaders headers   new HttpHeaders            headers add  Cache-Control    no-cache  no-store  must-revalidate            headers add  Pragma    no-cache            headers add  Expires    0            InputStreamReader i   new InputStreamReader new FileInputStream file2Upload            System out println  The length of the file is     file2Upload length              return ResponseEntity ok   headers headers  contentLength file2Upload length                     contentType MediaType parseMediaType  application octet-stream                     body i               When I tried to download the file from the browser  it starts the download  but always fails  Is there anything wrong with the service which is causing the download to fail

User · Answer

I want to share a simple approach for downloading files with JavaScript (ES6), React and a Spring Boot backend:

Spring boot Rest Controller

Resource from org.springframework.core.io.Resource

    @SneakyThrows
    @GetMapping("/files/{filename:.+}/{extraVariable}")
    @ResponseBody
    public ResponseEntity<Resource> serveFile(@PathVariable String filename, @PathVariable String extraVariable) {

        Resource file = storageService.loadAsResource(filename, extraVariable);
        return ResponseEntity.ok()
               .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + file.getFilename() + "\"")
               .body(file);
    }

React, API call using AXIOS

Set the responseType to arraybuffer to specify the type of data contained in the response.

export const DownloadFile = (filename, extraVariable) => {
let url = 'http://localhost:8080/files/' + filename + '/' + extraVariable;
return axios.get(url, { responseType: 'arraybuffer' }).then((response) => {
    return response;
})};

Final step > downloading
with the help of js-file-download you can trigger browser to save data to file as if it was downloaded.

DownloadFile('filename.extension', 'extraVariable').then(
(response) => {
    fileDownload(response.data, filename);
}
, (error) => {
    // ERROR 
});

User · Answer

using Apache IO could be another option for copy the Stream  RequestMapping path    quot  file  fileId  quot   method   RequestMethod GET  produces   MediaType APPLICATION JSON VALUE  public ResponseEntity lt   gt  downloadFile  PathVariable value  quot fileId quot   String fileId HttpServletResponse response  throws Exception        InputStream yourInputStream           IOUtils copy yourInputStream  response getOutputStream         response flushBuffer        return ResponseEntity ok   build       maven dependency      lt dependency gt           lt groupId gt org apache commons lt  groupId gt           lt artifactId gt commons-io lt  artifactId gt           lt version gt 1 3 2 lt  version gt       lt  dependency gt

User · Answer

GetMapping   downloadfile  productId   fileName    public ResponseEntity lt Resource gt  downloadFile  PathVariable value    productId   String productId           PathVariable String fileName  HttpServletRequest request           Load file as Resource     Resource resource       String fileBasePath    C   Users  v fzhang  mobileid  src  main  resources  data  Filesdown      productId                         Path path   Paths get fileBasePath   fileName       try           resource   new UrlResource path toUri           catch  MalformedURLException e            e printStackTrace            return null                Try to determine file s content type     String contentType   null      try           contentType   request getServletContext   getMimeType resource getFile   getAbsolutePath           catch  IOException ex            System out println  Could not determine file type                   Fallback to the default content type if type could not be determined     if  contentType    null            contentType    application octet-stream              return ResponseEntity ok   contentType MediaType parseMediaType contentType                header HttpHeaders CONTENT DISPOSITION   attachment  filename       resource getFilename                        body resource       To test it  use postman  http   localhost 8080 api downloadfile GDD 1 zip

User · Answer

The below Sample code worked for me and might help someone   import org springframework core io ByteArrayResource  import org springframework core io Resource  import org springframework http HttpHeaders  import org springframework http MediaType  import org springframework http ResponseEntity  import org springframework web bind annotation RequestMapping  import org springframework web bind annotation RequestMethod  import org springframework web bind annotation RequestParam  import org springframework web bind annotation RestController   import java io File  import java io IOException  import java nio file Files  import java nio file Path  import java nio file Paths    RestController  RequestMapping   app   public class ImageResource        private static final String EXTENSION     jpg       private static final String SERVER LOCATION     server images         RequestMapping path     download   method   RequestMethod GET      public ResponseEntity lt Resource gt  download  RequestParam  image   String image  throws IOException           File file   new File SERVER LOCATION   File separator   image   EXTENSION            HttpHeaders header   new HttpHeaders            header add HttpHeaders CONTENT DISPOSITION   attachment  filename img jpg            header add  Cache-Control    no-cache  no-store  must-revalidate            header add  Pragma    no-cache            header add  Expires    0             Path path   Paths get file getAbsolutePath             ByteArrayResource resource   new ByteArrayResource Files readAllBytes path             return ResponseEntity ok                    headers header                   contentLength file length                     contentType MediaType parseMediaType  application octet-stream                     body resource

User · Answer

I would suggest using a StreamingResponseBody since with it the application can write directly to the response  OutputStream  without holding up the Servlet container thread  It is a good approach if you are downloading a file very large    GetMapping  download   public StreamingResponseBody downloadFile HttpServletResponse response   PathVariable Long fileId         FileInfo fileInfo   fileService findFileInfo fileId       response setContentType fileInfo getContentType         response setHeader          HttpHeaders CONTENT DISPOSITION   attachment filename       fileInfo getFilename                 return outputStream - gt            int bytesRead          byte   buffer   new byte BUFFER SIZE           InputStream inputStream   fileInfo getInputStream            while   bytesRead   inputStream read buffer      -1                outputStream write buffer  0  bytesRead                        Ps   When using StreamingResponseBody  it is highly recommended to configure TaskExecutor used in Spring MVC for executing asynchronous requests  TaskExecutor is an interface that abstracts the execution of a Runnable   More info  https   medium com swlh streaming-data-with-spring-boot-restful-web-service-87522511c071

User · Answer

If you need to download a huge file from the server s file system  then ByteArrayResource can take all Java heap space  In that case  you can use FileSystemResource

User · Answer

Option 1 using an InputStreamResource     Resource implementation for a given InputStream       Should only be used if no other specific Resource implementation is   applicable  In particular  prefer ByteArrayResource or any of the file-based Resource implementations where possible      RequestMapping path     download   method   RequestMethod GET  public ResponseEntity lt Resource gt  download String param  throws IOException                    InputStreamResource resource   new InputStreamResource new FileInputStream file         return ResponseEntity ok                headers headers               contentLength file length                 contentType MediaType APPLICATION OCTET STREAM               body resource         Option2 as the documentation of the InputStreamResource suggests - using a ByteArrayResource    RequestMapping path     download   method   RequestMethod GET  public ResponseEntity lt Resource gt  download String param  throws IOException                    Path path   Paths get file getAbsolutePath         ByteArrayResource resource   new ByteArrayResource Files readAllBytes path         return ResponseEntity ok                headers headers               contentLength file length                 contentType MediaType APPLICATION OCTET STREAM               body resource

[java] download a file from Spring boot rest service

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