Develop Reference

How to set file type when it's downloaded?

I have this Spring endpoint which returns file:
#RequestMapping(value = "/files/{merchant_id}", method = RequestMethod.GET)
public void getFile(#PathVariable("merchant_id") Integer merchant_id, HttpServletResponse response) {
try {
File initialFile = new File("/opt/1/Why_Brookfield_Callout_3x.png");
InputStream is = FileUtils.openInputStream(initialFile);
org.apache.commons.io.IOUtils.copy(is, response.getOutputStream());
response.flushBuffer();
} catch (IOException ex) {
throw new RuntimeException("IOError writing file to output stream");
}
}
But when I download the file I get type text.
How I can set the type of there file to .png file?

add produces = MediaType.IMAGE_PNG in your #RequestMapping
see https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/http/MediaType.html for more mediatypes
So the method definition becomes:
#RequestMapping(value = "/files/{merchant_id}", method = RequestMethod.GET, produces = org.springframework.http.MediaType.IMAGE_PNG)

Not able to read InputStream data in rest api

I am passing file/img(form data) from my angular app to my rest api as a post method body.
But i am not able to read inputStream content.
My Rest api method:-
#RequestMapping(path = "/upload", method = RequestMethod.POST)
#Consumes(MediaType.MULTIPART_FORM_DATA)
public void process(#FormDataParam("file") InputStream dataStream) throws IOException {
this.writeToFile(dataStream, "src/main/resources/targetFile.jpg");
}
private void writeToFile(InputStream uploadedInputStream, String uploadedFileLocation) {
try {
byte[] image = IOUtils.toByteArray(uploadedInputStream);
OutputStream out = new FileOutputStream(new File(uploadedFileLocation));
IOUtils.write(image, out);
out.flush();
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
image array is always empty and hence empty file gets created in destination dir.
Anything wrong with the implementation?

You can code rest service like this.
Controller method
#RequestMapping(value="/upload", method=RequestMethod.POST)
public void handleFileUpload(#RequestParam("file") MultipartFile file){
writeToFile(file, "src/main/resources/targetFile.jpg");
}
writeToFile method
private void writeToFile(MultipartFile file, String uploadedFileLocation) {
if (!file.isEmpty()) {
try {
byte[] bytes = file.getBytes();
BufferedOutputStream stream = new BufferedOutputStream(new FileOutputStream(new File(uploadedFileLocation)));
stream.write(bytes);
stream.close();
} catch (Exception e) {
System.out.println(e.getMessage());
}
} else {
System.out.println("Empty file");
}
}

Uploading image from android app to Spring server

I have a problem with uploading image from android application to spring server. First of all i have this method on my server:
#RequestMapping(value = "/upload", method = RequestMethod.POST)
public String fileUpload(#RequestBody MultipartFile file) {
System.out.println("post image");
try {
// Get the file and save it somewhere
byte[] bytes = file.getBytes();
System.out.println(bytes.length);
//save file in server - you may need an another scenario
Path path = Paths.get("file:///E:/together/images/" + file.getOriginalFilename());
Files.write(path, bytes);
} catch (IOException e) {
e.printStackTrace();
}
//redirect to an another url end point
return "redirect";
}
And in my android app i'am get uri of image from image gallery and try call post method
FileEntity fileEntity = new FileEntity(new File(getRealPathFromURI(uri)), "application/octet-stream");
new Requests.Async().execute(fileEntity);
ublic static class Async extends AsyncTask<FileEntity,Void,Void>{
#Override
protected void onPreExecute() {
restTemplate = RestTemplateSingleton.newInstance().getRestTemplate();
}
#Override
protected Void doInBackground(FileEntity... uris) {
try{
restTemplate.postForObject(Requests.insertImage(),uris[0],FileEntity.class);
}catch (HttpClientErrorException | HttpServerErrorException httpClientOrServerExc) {
return null;
}
return null;
}
}
but i get 500 http status when call this method. what's my mistake?

How can i download the PDF file in spring mvc?

this is my file path
public final static String BOOKINGPDFFILE= "D:/Hotels/pdf/";
This below code is what I have written to download pdf from the above resource folder
Pdf="column name in database i used for storing in database"
#RequestMapping(value = "/getpdf/{pdf}", method = RequestMethod.GET)
public void getPdf(#PathVariable("pdf") String fileName, HttpServletResponse response,HttpServletRequest request) throws IOException {
try {
File file = new File(FileConstant.BOOKINGPDFFILE + fileName+ ".pdf");
Files.copy(file.toPath(),response.getOutputStream());
} catch (IOException ex) {
System.out.println("Contract Not Found");
System.out.println(ex.getMessage());
}
}

Here is the way, hope it help.
#RequestMapping(value = "/getpdf/{pdf}", method = RequestMethod.GET)
public void getPdf(#PathVariable("pdf") String fileName, HttpServletResponse response) throws IOException {
try {
File file = new File(FileConstant.BOOKINGPDFFILE + fileName+ ".pdf");
if (file.exists()) {
// here I use Commons IO API to copy this file to the response output stream, I don't know which API you use.
FileUtils.copyFile(file, response.getOutputStream());
// here we define the content of this file to tell the browser how to handle it
response.setContentType("application/pdf");
response.setHeader("Content-disposition", "attachment;filename=" + fileName + ".pdf");
response.flushBuffer();
} else {
System.out.println("Contract Not Found");
}
} catch (IOException exception) {
System.out.println("Contract Not Found");
System.out.println(exception.getMessage());
}
}

You may try something like this:
#RequestMapping(method = { RequestMethod.GET }, value = { "/downloadPdf" })
public ResponseEntity<InputStreamResource> downloadPdf()
{
try
{
File file = new File(BOOKINGPDFFILE);
HttpHeaders respHeaders = new HttpHeaders();
MediaType mediaType = MediaType.parseMediaType("application/pdf");
respHeaders.setContentType(mediaType);
respHeaders.setContentLength(file.length());
respHeaders.setContentDispositionFormData("attachment", file.getName());
InputStreamResource isr = new InputStreamResource(new FileInputStream(file));
return new ResponseEntity<InputStreamResource>(isr, respHeaders, HttpStatus.OK);
}
catch (Exception e)
{
String message = "Errore nel download del file "+idForm+".csv; "+e.getMessage();
logger.error(message, e);
return new ResponseEntity<InputStreamResource>(HttpStatus.INTERNAL_SERVER_ERROR);
}
}
And in your web page you can write the link in this way:
download PDF

You need to create an implementation of AbstractPdfView to achieve this.. You can refer this link https://www.mkyong.com/spring-mvc/spring-mvc-export-data-to-pdf-file-via-abstractpdfview/

Here is the Detailed answer for your question.
let me start with the server side code:
Below class is used to create pdf with some random content and return the equivalent byte array outputstream.
public class pdfgen extends AbstractPdfView{
private static ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
public ByteArrayOutputStream showHelp() throws Exception {
Document document = new Document();
// System.IO.MemoryStream ms = new System.IO.MemoryStream();
PdfWriter.getInstance(document,byteArrayOutputStream);
document.open();
document.add(new Paragraph("table"));
document.add(new Paragraph(new Date().toString()));
PdfPTable table=new PdfPTable(2);
PdfPCell cell = new PdfPCell (new Paragraph ("table"));
cell.setColspan (2);
cell.setHorizontalAlignment (Element.ALIGN_CENTER);
cell.setPadding (10.0f);
//cell.setBackgroundColor (new BaseColor (140, 221, 8));
table.addCell(cell);
ArrayList<String[]> row=new ArrayList<String[]>();
String[] data=new String[2];
data[0]="1";
data[1]="2";
String[] data1=new String[2];
data1[0]="3";
data1[1]="4";
row.add(data);
row.add(data1);
for(int i=0;i<row.size();i++) {
String[] cols=row.get(i);
for(int j=0;j<cols.length;j++){
table.addCell(cols[j]);
}
}
document.add(table);
document.close();
return byteArrayOutputStream;
}
}
Then comes the controller code : here the bytearrayoutputstream is converted to bytearray and sent to the client side using the response-entity with appropriate headers.
#RequestMapping(path="/home")
public ResponseEntity<byte[]> render(HttpServletRequest request , HttpServletResponse response) throws IOException
{
pdfgen pg=new pdfgen();
response.setContentType("application/pdf");
response.setHeader("Content-Disposition", "attachment:filename=report.pdf");
byte[] contents = null;
try {
contents = pg.showHelp().toByteArray();
}
catch (Exception e) {
e.printStackTrace();
}
//These 3 lines are used to write the byte array to pdf file
/*FileOutputStream fos = new FileOutputStream("/Users/naveen-pt2724/desktop/nama.pdf");
fos.write(contents);
fos.close();*/
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.parseMediaType("application/pdf"));
//Here you have to set the actual filename of your pdf
String filename = "output.pdf";
headers.setContentDispositionFormData(filename, filename);
headers.setCacheControl("must-revalidate, post-check=0, pre-check=0");
ResponseEntity<byte[]> respons = new ResponseEntity<byte[]>(contents, headers, HttpStatus.OK);
return respons;
}
The header should be set to "application/pdf"
Then comes the client side code :
Where you can make ajax request to server to open the pdf file in new tab of the browser
$.ajax({
url:'/PDFgen/home',
method:'POST',
cache:false,
xhrFields: {
responseType: 'blob'
},
success: function(data) {
//alert(data);
let blob = new Blob([data], {type: 'application/pdf'}); //mime type is important here
let link = document.createElement('a'); //create hidden a tag element
let objectURL = window.URL.createObjectURL(blob); //obtain the url for the pdf file
link.href = objectURL; // setting the href property for a tag
link.target = '_blank'; //opens the pdf file in new tab
link.download = "fileName.pdf"; //makes the pdf file download
(document.body || document.documentElement).appendChild(link); //to work in firefox
link.click(); //imitating the click event for opening in new tab
},
error:function(xhr,stats,error){
alert(error);
}
});

Try this
#Controller
#RequestMapping("/download")
public class FileDownloadController
{
#RequestMapping("/pdf/{fileName}")
public void downloadPDFResource( HttpServletRequest request,
HttpServletResponse response,
#PathVariable("fileName") String fileName)
{
//If user is not authorized - he should be thrown out from here itself
//Authorized user will download the file
String dataDirectory = request.getServletContext().getRealPath("/WEB-INF/downloads/pdf/");
Path file = Paths.get(dataDirectory, fileName);
if (Files.exists(file))
{
response.setContentType("application/pdf");
response.addHeader("Content-Disposition", "attachment; filename="+fileName);
try
{
Files.copy(file, response.getOutputStream());
response.getOutputStream().flush();
}
catch (IOException ex) {
ex.printStackTrace();
}
}
}
}

Jersey: Set response content-type based on file extension or InputStream?

I am using Jersey to serve a bunch of media-type files from resource folder inside a Jar file. I have the file URL returned by getClassLoader().getResource() and the InputStream returned by getClassLoader().getResourceAsStream(), is there a way for Jersey to detect the content-type for this file?

#GET
#Path("/attachment")
#Consumes("text/plain; charset=UTF-8")
#Produces(MediaType.APPLICATION_OCTET_STREAM)
public Response getAttachment(
#QueryParam("file") String fileName) {
try {
if (fileName == null) {
System.err.println("No such item");
return Response.status(Response.Status.BAD_REQUEST).build();
}
StreamingOutput stream = new StreamingOutput() {
#Override
public void write(OutputStream output) throws IOException {
try {
// TODO: write file content to output;
} catch (Exception e) {
e.printStackTrace();
}
}
};
return Response.ok(stream, "image/png") //TODO: set content-type of your file
.header("content-disposition", "attachment; filename = "+ fileName)
.build();
}
}
System.err.println("No such attachment");
return Response.status(Response.Status.BAD_REQUEST).build();
} catch (Exception e) {
System.err.println(e.getMessage());
return Response.status(Response.Status.BAD_REQUEST).build();
}
}
At the second TODO you can use (if Java 7):
Path source = Paths.get("/images/something.png");
Files.probeContentType(source);
to retrieve the mimeType.

I didn't find a solution using Jersey. But I found Apache Tika works perfectly in this case, simply do
Tika tika = new Tika();
String contentType = tika.detect(path);
where path is the abstract file path, like "index.html, ui.js, test.css"