I'm working on a spring boot project with thymeleaf and I need to create a file and put some lines on it then send it for the user to download it.
#PostMapping("/filegenerator")
public String createFile(#ModelAttribute("page") Page page, Model model) {
List<String> lines = new ArrayList<String>();
//Some code ..........
lines.forEach(l->{
System.out.println(l);
});
//Here I need to create a file with the List of lines
//And also put some code to download it
return "filegenerator";
}
So if you want to return a file, you probably want to stream it to limit the amount of memory used (or at least that was probably the reasoning of Spring Framework creators). In your case I understand that the file is fairly small and doesn't really have to be persisted anywhere. It's just a one time download based on the uploaded form, right?
so this approach worked on my PC:
#PostMapping("/filegenerator")
public void createFile(HttpServletResponse response) throws IOException {
List<String> lines = Arrays.asList("line1", "line2");
InputStream is = new ByteArrayInputStream(lines.stream().collect(Collectors.joining("\n")).getBytes());
IOUtils.copy(is, response.getOutputStream());
response.setContentType("application/sql");
response.setHeader("Content-Disposition", "attachment; filename=\"myquery.sql\"");
response.flushBuffer();
}
note the content-disposition header. It explicitly states that you don't want to display the file in the browser, but instead you want it to be downloaded as a file and myquery.sql is the name of that file that will be downloaded.
#Kamil janowski
This is how it looks like now
#PostMapping("/filegenerator")
public String createFile(#ModelAttribute("page") Page page, Model model,HttpServletResponse response) throws IOException{
List<String> lines = new ArrayList<String>();
if(page.getTables().get(0).getName()!="") {
List<String> output = so.createTable(page.getTables());
output.forEach(line -> lines.add(line));
}
if(page.getInserttables().get(0).getName()!="") {
List<String> output = so.insert(page.getInserttables());
output.forEach(line -> lines.add(line));
}
if(page.getUpdatetables().get(0).getName()!="") {
List<String> output = so.update(page.getUpdatetables());
output.forEach(line -> lines.add(line));
}
lines.forEach(l->{
System.out.println(l);
});
InputStream is = new ByteArrayInputStream(lines.stream().collect(Collectors.joining("\n")).getBytes());
IOUtils.copy(is, response.getOutputStream());
response.setContentType("application/sql");
response.setHeader("Content-Disposition", "attachment; filename=\"myquery.sql\"");
response.flushBuffer();
model.addAttribute("page", getPage());
return "filegenerator";
}
Related
I have a Quarkus based REST API project in which one endpoint is supposed to serve exported data as .csv files. Since i do not want to create temporary files, i was writing to a ByteArrayInputStream to be used in an octet stream response for my webservice.
However, although this works fine for latin character content we also have content that may be in Chinese. The downloaded .csv file does not view the characters properly or rather does not write them properly (they only show up as question marks, even in plain text view e.g. with notepad).
We already checked the source of the problem not being how the data is stored, for example the encoding in the database is correct and it works fine when we export it as .json (here we can set charset utf-8).
As far as i understand a charset or encoding cannot be set for an octet stream.
So how can we export/stream this content as a file download without creating an actual file?
Some code examples below on how we do it currently. We use the apache common library component CSVPrinter to create the CSV format in text in a custom CSV streamer class:
#ApplicationScoped
public class JobRunDataCsvStreamer implements DataFormatStreamer<JobData> {
#Override
public ByteArrayInputStream streamDataToFormat(List<JobData> dataList) {
try {
ByteArrayOutputStream out = getCsvOutputStreamFor(dataList);
return new ByteArrayInputStream(out.toByteArray());
} catch (IOException e) {
throw new RuntimeException("Failed to convert job data: " + e.getMessage());
}
}
private ByteArrayOutputStream getCsvOutputStreamFor(List<JobData> dataList) throws IOException {
ByteArrayOutputStream out = new ByteArrayOutputStream();
CSVPrinter csvPrinter = new CSVPrinter(new PrintWriter(out), getHeaderFormat());
for (JobData jobData : dataList) {
csvPrinter.printRecord(extractStringRowData(jobData));
}
csvPrinter.flush();
csvPrinter.close();
return out;
}
private CSVFormat getHeaderFormat() {
return CSVFormat.EXCEL
.builder()
.setDelimiter(";")
.setHeader("ID", "Source term", "Target term")
.build();
}
private List<String> extractStringRowData(JobData jobData) {
return Arrays.asList(
String.valueOf(jobData.getId()),
jobData.getSourceTerm(),
jobData.getTargetTerm()
);
}
}
Here is the quarkus API endpoint for the download:
#Path("/jobs/data")
public class JobDataResource {
#Inject JobDataRepository jobDataRepository;
#Inject JobDataCsvStreamer jobDataCsvStreamer;
...
#GET
#Path("/export/csv")
#Produces(MediaType.APPLICATION_OCTET_STREAM)
public Response getAllAsCsvExport() {
List<JobData> jobData = jobDataRepository.getAll();
ByteArrayInputStream stream = jobDataCsvStreamer.streamDataToFormat(jobData);
return Response.ok(stream, MediaType.APPLICATION_OCTET_STREAM)
.header("content-disposition", "attachment; filename = job-data.csv")
.build();
}
}
Screenshot of result in the downloaded file for chinese characters in the second column:
We tried setting headers etc. for encoding, but none of it worked. Is there a way to stream content which requires specific encoding as a file in Java web services? We tried using PrintWriter which works, but requies creating a local file on the server.
Edit: We tried using PrintWriter(out, false, StandardCharsets.UTF_8) for the PrintWriter to write to a byte array out stream for the response, which yields a different result but still with broken view in both Excel and plain text:
Screenshot:
Code for endpoint:
#GET
#Path("/export/csv")
#Produces(MediaType.APPLICATION_OCTET_STREAM)
public Response getAllAsCsvExport() {
List<JobData> jobData = jobRunDataRepository.getAll();
ByteArrayOutputStream out = new ByteArrayOutputStream();
try{
PrintWriter pw = new PrintWriter(out, false, StandardCharsets.UTF_8);
pw.println(String.format("%s, %s, %s", "ID", "Source", "Target"));
for (JobData item : jobData) {
pw.println(String.format("%s, %s, %s",
String.valueOf(item.getId()),
String.valueOf(item.getSourceTerm()),
String.valueOf(item.getTargetTerm()))
);
}
pw.flush();
pw.close();
} catch (Exception e) {
throw new RuntimeException("Failed to convert job data: " + e.getMessage());
}
return Response.ok(out).build();
}
I would like to write a Spring controller method which returns an image from storage. Below is my current version, but it has two problems:
The #GetMapping annotation requires the 'produces' parameter which is a string array of media types. The program does not work if that parameter is not present; it just displays the image data as text. The problem is that if I want to support an additional media type then I have to recompile the program. Is there a way to set up the 'produces' media type from inside the viewImg method?
The code below will display any image type except svg, which will display only the message "The image cannot be displayed because it contains errors". The web browser (Firefox) identifies it as media type "webp". However, if I remove all media types from the 'produces' string array except the "image/svg+xml" entry, the image is displayed.
Please advise how to write a controller method that is more general (so that it works with any media type) and does not have issues with svg media type.
Here is my test code:
#GetMapping(value = "/pic/{id}",
produces = {
"image/bmp",
"image/gif",
"image/jpeg",
"image/png",
"image/svg+xml",
"image/tiff",
"image/webp"
}
)
public #ResponseBody
byte[] viewImg(#PathVariable Long id) {
byte[] data = new byte[0];
String inputFile = "/path/to/image.svg";
try {
InputStream inputStream = new FileInputStream(inputFile);
long fileSize = new File(inputFile).length();
data = new byte[(int) fileSize];
inputStream.read(data);
} catch (IOException e) {
e.printStackTrace();
}
return data;
}
I recommend FileSystemResource for handling file contents. You can avoid .contentType(..) started line if you don't want to send Content-Type value.
#GetMapping("/pic/{id}")
public ResponseEntity<Resource> viewImg(#PathVariable Long id) throws IOException {
String inputFile = "/path/to/image.svg";
Path path = new File(inputFile).toPath();
FileSystemResource resource = new FileSystemResource(path);
return ResponseEntity.ok()
.contentType(MediaType.parseMediaType(Files.probeContentType(path)))
.body(resource);
}
I'm struggling with getting file upload/download to work properly in Play framework 2.2.2. I have a Student class with a field called "cv". It's annotated with #Lob, like this:
#Lob
public byte[] cv;
Here are the upload and download methods:
public static Result upload() {
MultipartFormData body = request().body().asMultipartFormData();
FilePart cv = body.getFile("cv");
if (cv != null) {
filenameCV = cv.getFilename();
String contentType = cv.getContentType();
File file = cv.getFile();
Http.Session session = Http.Context.current().session();
String studentNr = session.get("user");
Student student = Student.find.where().eq("studentNumber", studentNr).findUnique();
InputStream is;
try {
is = new FileInputStream(file);
student.cv = IOUtils.toByteArray(is);
} catch (IOException e) {
Logger.debug("Error converting file");
}
student.save();
flash("ok", "Vellykket! Filen " + filenameCV + " ble lastet opp til din profil");
return redirect(routes.Profile.profile());
} else {
flash("error", "Mangler fil");
return redirect(routes.Profile.profile());
}
}
public static Result download() {
Http.Session session = Http.Context.current().session();
Student student = Student.find.where().eq("studentNumber", session.get("user")).findUnique();
File f = new File("/tmp/" +filenameCV);
FileOutputStream fos;
try {
fos = new FileOutputStream(f);
fos.write(student.cv);
fos.flush();
fos.close();
} catch(IOException e) {
}
return ok(f);
}
The file seems to be correctly saved to the database (the cv field is populated with data, but it's obviously cryptic to me so I don't know for sure that the content is what it's supposed to be)
When I go to my website and click the "Download CV" link (which runs the download action), the file gets downloaded but can't be opened - saying the PDF viewer can't recognize the file etc. (Files uploaded have to be PDF)
Any ideas on what might be wrong?
Don't keep your files in DB, filesystem is much better for that! Save uploaded file on the disk with some unique name, then in your database keep only path to the file as a String!
It's cheaper in longer run (as said many times)
It's easier to handle downloads, i.e. in Play all you need to serve PDF is:
public static Result download() {
File file = new File("/full/path/to/your.pdf");
return ok(file);
}
it will set proper headers, like Content-Disposition, Content-Length and Content-Type not only for PDFs
I have a utility class I created for my Spring controller to invoke to generate a CSV from a collection of beans using the SuperCSV library ( http://supercsv.sourceforge.net/ )
The utility class is pretty basic:
public static void export2CSV(HttpServletResponse response,
String[] header, String filePrefix, List<? extends Object> dataObjs) {
try{
response.setContentType("text/csv;charset=utf-8");
response.setHeader("Content-Disposition","attachment; filename="+filePrefix+"_Data.csv");
OutputStream fout= response.getOutputStream();
OutputStream bos = new BufferedOutputStream(fout);
OutputStreamWriter outputwriter = new OutputStreamWriter(bos);
ICsvBeanWriter writer = new CsvBeanWriter(outputwriter, CsvPreference.EXCEL_PREFERENCE);
// the actual writing
writer.writeHeader(header);
for(Object anObj : dataObjs){
writer.write(anObj, header);
}
}catch (Exception e){
e.printStackTrace();
}
};
The catch is, I'm getting different behaviors out of this operation and I don't know why. When I invoke it from one controller (we'll call it 'A'), I get the expected output of data.
When I invoke it from the other controller ('B'), I get a tiny blurb of unrecognizable binary data that cannot be opened by OO Calc. Opening it in Notepad++ yields an unreadable line of gibberish that I can only assume is an attempt by the reader to show me a binary stream.
Controller 'A' invocation (the one that works)
#RequestMapping(value="/getFullReqData.html", method = RequestMethod.GET)
public void getFullData(HttpSession session, HttpServletRequest request, HttpServletResponse response) throws IOException{
logger.info("INFO: ******************************Received request for full Req data dump");
String projName= (String)session.getAttribute("currentProject");
int projectID = ProjectService.getProjectID(projName);
List<Requirement> allRecords = reqService.getFullDataSet(projectID);
final String[] header = new String[] {
"ColumnA",
"ColumnB",
"ColumnC",
"ColumnD",
"ColumnE"
};
CSVExporter.export2CSV(response, header, projName+"_reqs_", allRecords);
};
...and here's the Controller 'B' invocation (the one that fails):
#RequestMapping(value="/getFullTCData.html", method = RequestMethod.GET)
public void getFullData(HttpSession session, HttpServletRequest request, HttpServletResponse response) throws IOException{
logger.info("INFO: Received request for full TCD data dump");
String projName= (String)session.getAttribute("currentProject");
int projectID = ProjectService.getProjectID(projName);
List<TestCase> allRecords = testService.getFullTestCaseList(projectID);
final String[] header = new String[] {
"ColumnW",
"ColumnX",
"ColumnY",
"ColumnZ"
};
CSVExporter.export2CSV(response, header, projName+"_tcs_", allRecords);
}
Observations:
Which controller I invoke first is irrelevant. 'A' always works and 'B' always produces gibberish
Both calls to this function have a list of header columns that are a subset of the total set of operations defined in the bean being passed in to CSVWriter
The simple Exception printStackTrace is working to detect when a bean's reflection field doesn't match the definition (i.e., can't find get() to get the value programmatically) suggesting that all column/variable matchups are succeeding.
In the debugger, I've verified the writer.write(Object, header) call is being hit the expected number of times based on the number of objects being passed and that these objects have the expected data
Any suggestions or insights would be greatly appreciated. I'm really stumped how to better isolate the issue...
You aren't closing the writer. Also, CsvBeanWriter will wrap the writer in a BufferedWriter, so you can probably simplify your outputwriter as well.
public static void export2CSV(HttpServletResponse response,
String[] header, String filePrefix, List<? extends Object> dataObjs) {
ICsvBeanWriter writer;
try{
response.setContentType("text/csv;charset=utf-8");
response.setHeader("Content-Disposition",
"attachment; filename="+filePrefix+"_Data.csv");
OutputStreamWriter outputwriter =
new OutputStreamWriter(response.getOutputStream());
writer = new CsvBeanWriter(outputwriter, CsvPreference.EXCEL_PREFERENCE);
// the actual writing
writer.writeHeader(header);
for(Object anObj : dataObjs){
writer.write(anObj, header);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
writer.close(); // closes writer and underlying stream
} catch (Exception e){}
}
};
Super CSV 2.0.0-beta-1 is out now! As well as adding numerous other features (including Maven support and a new Dozer extension), CSV writers now expose a flush() method as well.
This is my download code. It just starts downloading the file without asking user. I've searched multiple forums and nothing seems to work. This is code is in a backing bean attached to a commandButton.
public void doDownloadFile() {
PrintWriter out = null;
try {
HttpServletResponse response = (HttpServletResponse) FacesContext.getCurrentInstance().getExternalContext().getResponse();
response.setContentType("application/vnd.ms-excel");
response.setHeader("Content-disposition", "attachment;filename=test.csv");
out = response.getWriter();
CSVWriter writer = new CSVWriter(out);
List<String[]> stringList = new ArrayList<String[]>();
for (User user : userList) {
String[] string = {user.getEmail(), user.getName(), user.getPassword()};
stringList.add(string);
}
writer.writeAll(stringList);
out.flush();
} catch (IOException ex) {
Logger.getLogger(ViewLines.class.getName()).log(Level.SEVERE, null, ex);
} finally {
out.close();
}
}
This is most likely due to the fact your browser is configured to download files of these types without prompt. The code has nothing to do with it.
The behavior of what to do with a download is 100% local, meaning it's the browser, not you, that determines what to do in that case. Whether the user's browser just dumps the file in a download folder or allows him to save it to a particular spot is entirely up to the browser.
Not much to be done.