Java 11 and Spring Boot 2.5.x here. I understand that I can set up a controller to return the contents of a file like so:
@GetMapping(
value = "/get-image-with-media-type",
produces = MediaType.IMAGE_JPEG_VALUE
)
public @ResponseBody byte[] getImageWithMediaType() throws IOException {
InputStream in = getClass()
.getResourceAsStream("/path/to/some/image.jpg");
return IOUtils.toByteArray(in);
}
But what if I want to control the name of the file that is sent back? For instance, on the server-side the file name might be stored as "image.jpg" but say I want to have it returned as "<userId>-<YYYY-mm-DD>-image.jpg", where <userId> is the user ID of the authenticated user making the request, and where <YYYY-mm-DD> is the date the request is made at?
For instance, if user 123 made the request on 12/10/2021, the file would be downloaded as "123-2021-12-10-image.jpg" and if user 234 made the request on 1/17/2022 it would be downloaded as "234-2022-01-17-image.jpg". Is this possible to control on the Spring/Java/server-side, or is it up to the HTTP client (browser, PostMan, whatever) to decide on the file name?
Please try this, comments inline:
package com.example;
import java.io.IOException;
import java.security.Principal;
import java.util.Date;
import org.apache.commons.io.IOUtils;
import org.springframework.core.io.FileSystemResource;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
@Controller
public class SomeController {
@GetMapping(
value = "/get-image-with-media-type",
produces = MediaType.IMAGE_JPEG_VALUE
) // we can inject user like this (can be null, when not secured):
public ResponseEntity<byte[]> getImageWithMediaType(Principal user) throws IOException {
// XXXResource is the "spring way", FileSystem- alternatively: ClassPath-, ServletContext-, ...
FileSystemResource fsr = new FileSystemResource("/path/to/some/image.jpg");
HttpHeaders responseHeaders = new HttpHeaders();
responseHeaders.set(HttpHeaders.CONTENT_DISPOSITION,
// for direct downlad "inline", for "save as" dialog "attachment" (browser dependent)
// filename placeholders: %1$s: user id string, 2$tY: year 4 digits, 2$tm: month 2 digits, %2$td day of month 2 digits
String.format("inline; filename=\"%1$s-%2$tY-%2$tm-%2$td-image.jpg\"",
// user name, current (server) date:
user == null ? "anonymous" : user.getName(), new Date()));
// and fire:
return new ResponseEntity<>(
IOUtils.toByteArray(fsr.getInputStream()),
responseHeaders,
HttpStatus.OK
);
}
}
Relevant reference:
With ContentDisposition it can look (just) like:
responseHeaders.setContentDisposition(
ContentDisposition
.inline()// or .attachment()
.filename(// format file name:
String.format(
"%1$s-%2$tY-%2$tm-%2$td-image.jpg",
user == null ? "anonymous" : user.getName(),
new Date()
)
)
.build()
);