Java Spring Boot Download file with filename containing special characters produces zero byte downloaded file

Question

JAVA_OPTS: -Dfile.encoding=UTF-8 -Dsun.jnu.encoding=UTF-8
File System : Linux
Spring Boot : 2.1.4
Spring framework: 5.1.6.RELEASE
Library used : org.springframework.core.io.FileSystemResource;

The problem exists for example in German characters. For filename containing space %20 (encoded) works fine.

The problematic file is named Einzelh?ndler überprüfen.pdf and it's 12KB

Locally in windows and IntelliJ it works okay but in Linux it doesn't download .

final String relativePath = Paths.get(directory, UriUtils.decode(fileName, StandardCharsets.UTF_8)).toString();

 

final FileSystemResource res = new FileSystemResource(relativePath);
final String actualFileName = res.getFile().toPath().getFileName().toString();

 

final HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
headers.setContentDisposition(ContentDisposition.builder("attachment").filename(actualFileName).build());

 

return new ResponseEntity<>(res, headers, HttpStatus.OK);

final String actualFileName = res.getFile().toPath().getFileName().toString();

I have tried also this line with

final String actualFileName = UriUtils.encode(res.getFile().toPath().getFileName().toString(), StandardCharsets.UTF_8)).toString()

Does anybody know why this problem is happening ?

question from:https://stackoverflow.com/questions/65682390/java-spring-boot-download-file-with-filename-containing-special-characters-produ

Answer 1

I think you have a problem with different file encodings. The best approach would be that you first analyze which OS your application running at and then work your way up to result like this.

 String input = new String(input_bytes, StandartCharsets.UTF_8); // on linux
 String input = new String(input_bytes, StandartCharsets.ISO_8859_1); // on windows

And create a helper class as follows:

  class OsUtils
{
   private static String OS = null;
   public static String getOsName()
   {
      if(OS == null) { OS = System.getProperty("os.name"); }
      return OS;
   }
   public static boolean isWindows()
   {
      return getOsName().startsWith("Windows");
   }

   public static boolean isUnix() {
       return getOsName().contains("nux");
   };// and so on
}

After, with some simple if check using the OsUtils classs, you can check which one to use. Hope it works!