Unable to write to disk using GridFSFile in springboot 2.0.2 - spring

Question

Trying to use code in:
http://javasampleapproach.com/spring-framework/spring-data/springdata-mongodb-gridfstemplate-save-retrieve-delete-binary-files-image-text-files
with springboot 1.5.13.
In this code to retrieve an image use GridFSDBFile like this:
GridFSDBFile imageFile = gridOperations.findOne(new Query(Criteria.where("_id").is(imageFileId)));
and later to save in filesystem use this:
imageFile.writeTo
Baeldung has the same code:
http://www.baeldung.com/spring-data-mongodb-gridfs
I have my project in springboot 2.0.2 and this line:
GridFSDBFile imageFile = gridOperations.findOne(new Query(Criteria.where("_id").is(imageFileId)));
throws an error:
Type mismatch: cannot convert from GridFSFile to GridFSDBFile
so, once I have changed to:
GridFSFile imageFile = gridOperations.findOne(new Query(Criteria.where("_id").is(imageFileId)));
no errors, but now I have not available the method:
writeTo
to write to disk.
UPDATE 1:
imageFileId = "5b0bff8b7cc45b32f43b47f4";
GridFSFile imageFile = gridOperations.findOne(new Query(Criteria.where("_id").is(imageFileId)));
try {
File file = new File("c:/JSA/retrieve/" + imageFile.getFilename());
FileOutputStream streamToDownloadTo = new FileOutputStream(file);
//This line doesn't works
gridFSBucket.downloadToStream(imageFile.getId(), streamToDownloadTo);
streamToDownloadTo.close();
} catch (IOException e) {
// handle exception
System.out.println("error: " + e.getMessage());
} catch (Exception e1) {
System.out.println("error1: " + e1.getMessage());
}
UPDATE 2:
try {
File file = new File("c:/JSA/retrieve/" + imageFile.getFilename());
FileOutputStream streamToDownloadTo = new FileOutputStream(file);
System.out.println("imageFile.getId(): " + imageFile.getId());
System.out.println("streamToDownloadTo: " + streamToDownloadTo.toString());
gridFSBucket.downloadToStream(imageFile.getId(), streamToDownloadTo);
streamToDownloadTo.close();
} catch (IOException e) {
// handle exception
System.out.println("error: " + e.getMessage());
} catch (Exception e1) {
System.out.println("error1: " + e1.getMessage());
}
Console
imageFile.getId(): BsonObjectId{value=5b0bff8b7cc45b32f43b47f4}
streamToDownloadTo: java.io.FileOutputStream#3b20c8e2
This line thrown an exception:
gridFSBucket.downloadToStream(imageFile.getId(), streamToDownloadTo);
and return null
Solved
Inject:
#Autowired
MongoGridFsTemplate mongoGridFsTemplate;
GridFSBucket gridFSBucket = GridFSBuckets.create(mongoGridFsTemplate.mongoDbFactory().getDb());
imageFileId = "5b0bff8b7cc45b32f43b47f4";
GridFSFile imageFile = gridOperations.findOne(new Query(Criteria.where("_id").is(new ObjectId(imageFileId))));
try {
File file = new File("c:/JSA/retrieve/" + imageFile.getFilename());
FileOutputStream streamToDownloadTo = new FileOutputStream(file);
gridFSBucket.downloadToStream(imageFile.getId(), streamToDownloadTo);
streamToDownloadTo.close();
} catch (IOException e) {
// handle exception
System.out.println("error: " + e.getMessage());
} catch (Exception e1) {
e1.printStackTrace();
}