Related
The bounty expires in 4 days. Answers to this question are eligible for a +100 reputation bounty.
Nzall wants to reward an existing answer.
I have a requirement where I need to download a PDF from the website. The PDF needs to be generated within the code, which I thought would be a combination of freemarker and a PDF generation framework like iText. Any better way?
However, my main problem is how do I allow the user to download a file through a Spring Controller?
#RequestMapping(value = "/files/{file_name}", method = RequestMethod.GET)
public void getFile(
#PathVariable("file_name") String fileName,
HttpServletResponse response) {
try {
// get your file as InputStream
InputStream is = ...;
// copy it to response's OutputStream
org.apache.commons.io.IOUtils.copy(is, response.getOutputStream());
response.flushBuffer();
} catch (IOException ex) {
log.info("Error writing file to output stream. Filename was '{}'", fileName, ex);
throw new RuntimeException("IOError writing file to output stream");
}
}
Generally speaking, when you have response.getOutputStream(), you can write anything there. You can pass this output stream as a place to put generated PDF to your generator. Also, if you know what file type you are sending, you can set
response.setContentType("application/pdf");
I was able to stream line this by using the built in support in Spring with it's ResourceHttpMessageConverter. This will set the content-length and content-type if it can determine the mime-type
#RequestMapping(value = "/files/{file_name}", method = RequestMethod.GET)
#ResponseBody
public FileSystemResource getFile(#PathVariable("file_name") String fileName) {
return new FileSystemResource(myService.getFileFor(fileName));
}
You should be able to write the file on the response directly. Something like
response.setContentType("application/pdf");
response.setHeader("Content-Disposition", "attachment; filename=\"somefile.pdf\"");
and then write the file as a binary stream on response.getOutputStream(). Remember to do response.flush() at the end and that should do it.
With Spring 3.0 you can use the HttpEntity return object. If you use this, then your controller does not need a HttpServletResponse object, and therefore it is easier to test.
Except this, this answer is relative equals to the one of Infeligo.
If the return value of your pdf framework is an byte array (read the second part of my answer for other return values) :
#RequestMapping(value = "/files/{fileName}", method = RequestMethod.GET)
public HttpEntity<byte[]> createPdf(
#PathVariable("fileName") String fileName) throws IOException {
byte[] documentBody = this.pdfFramework.createPdf(filename);
HttpHeaders header = new HttpHeaders();
header.setContentType(MediaType.APPLICATION_PDF);
header.set(HttpHeaders.CONTENT_DISPOSITION,
"attachment; filename=" + fileName.replace(" ", "_"));
header.setContentLength(documentBody.length);
return new HttpEntity<byte[]>(documentBody, header);
}
If the return type of your PDF Framework (documentBbody) is not already a byte array (and also no ByteArrayInputStream) then it would been wise NOT to make it a byte array first. Instead it is better to use:
InputStreamResource,
PathResource (since Spring 4.0) or
FileSystemResource,
example with FileSystemResource:
#RequestMapping(value = "/files/{fileName}", method = RequestMethod.GET)
public HttpEntity<byte[]> createPdf(
#PathVariable("fileName") String fileName) throws IOException {
File document = this.pdfFramework.createPdf(filename);
HttpHeaders header = new HttpHeaders();
header.setContentType(MediaType.APPLICATION_PDF);
header.set(HttpHeaders.CONTENT_DISPOSITION,
"attachment; filename=" + fileName.replace(" ", "_"));
header.setContentLength(document.length());
return new HttpEntity<byte[]>(new FileSystemResource(document),
header);
}
If you:
Don't want to load the whole file into a byte[] before sending to the response;
Want/need to send/download it via InputStream;
Want to have full control of the Mime Type and file name sent;
Have other #ControllerAdvice picking up exceptions for you (or not).
The code below is what you need:
#RequestMapping(value = "/stuff/{stuffId}", method = RequestMethod.GET)
public ResponseEntity<FileSystemResource> downloadStuff(#PathVariable int stuffId)
throws IOException {
String fullPath = stuffService.figureOutFileNameFor(stuffId);
File file = new File(fullPath);
long fileLength = file.length(); // this is ok, but see note below
HttpHeaders respHeaders = new HttpHeaders();
respHeaders.setContentType("application/pdf");
respHeaders.setContentLength(fileLength);
respHeaders.setContentDispositionFormData("attachment", "fileNameIwant.pdf");
return new ResponseEntity<FileSystemResource>(
new FileSystemResource(file), respHeaders, HttpStatus.OK
);
}
More on setContentLength(): First of all, the content-length header is optional per the HTTP 1.1 RFC. Still, if you can provide a value, it is better. To obtain such value, know that File#length() should be good enough in the general case, so it is a safe default choice.
In very specific scenarios, though, it can be slow, in which case you should have it stored previously (e.g. in the DB), not calculated on the fly. Slow scenarios include: if the file is very large, specially if it is on a remote system or something more elaborated like that - a database, maybe.
InputStreamResource
If your resource is not a file, e.g. you pick the data up from the DB, you should use InputStreamResource. Example:
InputStreamResource isr = new InputStreamResource(...);
return new ResponseEntity<InputStreamResource>(isr, respHeaders, HttpStatus.OK);
Do
Return ResponseEntity<Resource> from a handler method
Specify Content-Type
Set Content-Disposition if necessary:
filename
type
inline to force preview in a browser
attachment to force a download
Example
#Controller
public class DownloadController {
#GetMapping("/downloadPdf.pdf")
// 1.
public ResponseEntity<Resource> downloadPdf() {
FileSystemResource resource = new FileSystemResource("/home/caco3/Downloads/JMC_Tutorial.pdf");
// 2.
MediaType mediaType = MediaTypeFactory
.getMediaType(resource)
.orElse(MediaType.APPLICATION_OCTET_STREAM);
HttpHeaders headers = new HttpHeaders();
headers.setContentType(mediaType);
// 3
ContentDisposition disposition = ContentDisposition
// 3.2
.inline() // or .attachment()
// 3.1
.filename(resource.getFilename())
.build();
headers.setContentDisposition(disposition);
return new ResponseEntity<>(resource, headers, HttpStatus.OK);
}
}
Explanation
Return ResponseEntity<Resource>
When you return a ResponseEntity<Resource>, the ResourceHttpMessageConverter writes file contents
Examples of Resource implementations:
ByteArrayResource - based in byte[]
FileSystemResource - for a File or a Path
UrlResource - retrieved from java.net.URL
GridFsResource - a blob stored in MongoDB
ClassPathResource - for files in classpath, for example files from resources directory. My answer to question "Read file from resources folder in Spring Boot" explains how to locate the resource in classpath in details
Specify Content-Type explicitly:
Reason: see "FileSystemResource is returned with content type json" question
Options:
Hardcode the header
Use the MediaTypeFactory from Spring. The MediaTypeFactory maps Resource to MediaType using the /org/springframework/http/mime.types file
Use a third party library like Apache Tika
Set Content-Disposition if necessary:
About Content-Disposition header:
The first parameter in the HTTP context is either inline (default value, indicating it can be displayed inside the Web page, or as the Web page) or attachment (indicating it should be downloaded; most browsers presenting a 'Save as' dialog, prefilled with the value of the filename parameters if present).
Use ContentDisposition in application:
To preview a file in a browser:
ContentDisposition disposition = ContentDisposition
.inline()
.filename(resource.getFilename())
.build();
To force a download:
ContentDisposition disposition = ContentDisposition
.attachment()
.filename(resource.getFilename())
.build();
Use InputStreamResource carefully:
Specify Content-Length using the HttpHeaders#setContentLength method if:
The length is known
You use InputStreamResource
Reason: Spring won't write Content-Length for InputStreamResource because Spring can't determine the length of the resource. Here is a snippet of code from ResourceHttpMessageConverter:
#Override
protected Long getContentLength(Resource resource, #Nullable MediaType contentType) throws IOException {
// Don't try to determine contentLength on InputStreamResource - cannot be read afterwards...
// Note: custom InputStreamResource subclasses could provide a pre-calculated content length!
if (InputStreamResource.class == resource.getClass()) {
return null;
}
long contentLength = resource.contentLength();
return (contentLength < 0 ? null : contentLength);
}
In other cases Spring sets the Content-Length:
~ $ curl -I localhost:8080/downloadPdf.pdf | grep "Content-Length"
Content-Length: 7554270
This code is working fine to download a file automatically from spring controller on clicking a link on jsp.
#RequestMapping(value="/downloadLogFile")
public void getLogFile(HttpSession session,HttpServletResponse response) throws Exception {
try {
String filePathToBeServed = //complete file name with path;
File fileToDownload = new File(filePathToBeServed);
InputStream inputStream = new FileInputStream(fileToDownload);
response.setContentType("application/force-download");
response.setHeader("Content-Disposition", "attachment; filename="+fileName+".txt");
IOUtils.copy(inputStream, response.getOutputStream());
response.flushBuffer();
inputStream.close();
} catch (Exception e){
LOGGER.debug("Request could not be completed at this moment. Please try again.");
e.printStackTrace();
}
}
Below code worked for me to generate and download a text file.
#RequestMapping(value = "/download", method = RequestMethod.GET)
public ResponseEntity<byte[]> getDownloadData() throws Exception {
String regData = "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.";
byte[] output = regData.getBytes();
HttpHeaders responseHeaders = new HttpHeaders();
responseHeaders.set("charset", "utf-8");
responseHeaders.setContentType(MediaType.valueOf("text/html"));
responseHeaders.setContentLength(output.length);
responseHeaders.set("Content-disposition", "attachment; filename=filename.txt");
return new ResponseEntity<byte[]>(output, responseHeaders, HttpStatus.OK);
}
What I can quickly think of is, generate the pdf and store it in webapp/downloads/< RANDOM-FILENAME>.pdf from the code and send a forward to this file using HttpServletRequest
request.getRequestDispatcher("/downloads/<RANDOM-FILENAME>.pdf").forward(request, response);
or if you can configure your view resolver something like,
<bean id="pdfViewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="viewClass"
value="org.springframework.web.servlet.view.JstlView" />
<property name="order" value=”2″/>
<property name="prefix" value="/downloads/" />
<property name="suffix" value=".pdf" />
</bean>
then just return
return "RANDOM-FILENAME";
The following solution work for me
#RequestMapping(value="/download")
public void getLogFile(HttpSession session,HttpServletResponse response) throws Exception {
try {
String fileName="archivo demo.pdf";
String filePathToBeServed = "C:\\software\\Tomcat 7.0\\tmpFiles\\";
File fileToDownload = new File(filePathToBeServed+fileName);
InputStream inputStream = new FileInputStream(fileToDownload);
response.setContentType("application/force-download");
response.setHeader("Content-Disposition", "attachment; filename="+fileName);
IOUtils.copy(inputStream, response.getOutputStream());
response.flushBuffer();
inputStream.close();
} catch (Exception exception){
System.out.println(exception.getMessage());
}
}
something like below
#RequestMapping(value = "/download", method = RequestMethod.GET)
public void getFile(HttpServletResponse response) {
try {
DefaultResourceLoader loader = new DefaultResourceLoader();
InputStream is = loader.getResource("classpath:META-INF/resources/Accepted.pdf").getInputStream();
IOUtils.copy(is, response.getOutputStream());
response.setHeader("Content-Disposition", "attachment; filename=Accepted.pdf");
response.flushBuffer();
} catch (IOException ex) {
throw new RuntimeException("IOError writing file to output stream");
}
}
You can display PDF or download it examples here
If it helps anyone. You can do what the accepted answer by Infeligo has suggested but just put this extra bit in the code for a forced download.
response.setContentType("application/force-download");
In my case I'm generating some file on demand, so also url has to be generated.
For me works something like that:
#RequestMapping(value = "/files/{filename:.+}", method = RequestMethod.GET, produces = "text/csv")
#ResponseBody
public FileSystemResource getFile(#PathVariable String filename) {
String path = dataProvider.getFullPath(filename);
return new FileSystemResource(new File(path));
}
Very important is mime type in produces and also that, that name of the file is a part of the link so you has to use #PathVariable.
HTML code looks like that:
<a th:href="#{|/dbreport/files/${file_name}|}">Download</a>
Where ${file_name} is generated by Thymeleaf in controller and is i.e.: result_20200225.csv, so that whole url behing link is: example.com/aplication/dbreport/files/result_20200225.csv.
After clicking on link browser asks me what to do with file - save or open.
I had to add this to download any file
response.setContentType("application/octet-stream");
response.setHeader("Content-Disposition",
"attachment;filename="+"file.txt");
all code:
#Controller
public class FileController {
#RequestMapping(value = "/file", method =RequestMethod.GET)
#ResponseBody
public FileSystemResource getFile(HttpServletResponse response) {
final File file = new File("file.txt");
response.setContentType("application/octet-stream");
response.setHeader("Content-Disposition",
"attachment;filename="+"file.txt");
return new FileSystemResource(file);
}
}
This can be a useful answer.
Is it ok to export data as pdf format in frontend?
Extending to this, adding content-disposition as an attachment(default) will download the file. If you want to view it, you need to set it to inline.
I'm trying to download a file:
import org.apache.commons.io.IOUtils;
#GetMapping("/file")
public void file(#RequestParam("path") String path, HttpServletResponse response) throws IOException {
InputStream inStream = fmService.downloadFile("https://" + path);
IOUtils.copy(inStream, response.getOutputStream());
response.flushBuffer();
}
But when I visit localhost:8080/file?path=/Documents... a download gets not triggered.
If I use a txt file in the path, then the content of it is shown to me in the browser, but when I'm using a pdf file nothing really happens. Having 200 response code but no download.
How can I use spring-boot to download the files?
And the next step would be to call this spring-boot api endpoint and download from an Angular frontend.
I think the output must be different too then or?
You need to set the following header so that the browser knows to download a file from the returned response instead of displaying on browser. See
https://github.com/gtiwari333/spring-boot-blog-app/blob/master/src/main/java/gt/app/modules/file/FileDownloadUtil.java
response.setHeader("Content-Disposition", "attachment; filename=" + "a.txt");
A working GetMapping:
#GetMapping
void d(HttpServletResponse r) throws IOException {
r.setHeader("Content-Disposition", "attachment; filename=" + "a.txt");
r.getOutputStream().print("ABCD");
r.getOutputStream().flush();
}
//Or return input stream:
#GetMapping("/is")
void d(HttpServletResponse r) throws IOException {
r.setHeader("Content-Disposition", "attachment; filename=" + "a.txt");
InputStream is = new ByteArrayInputStream("Some test string".getBytes()); //or any input stream
org.apache.commons.io.IOUtils.copy(is, r.getOutputStream());
r.getOutputStream().flush();
}
Downloading file from angular app:
This gets tricky and needs to be done in three steps:
a first call to get direct link to the file
render the link in anchor tag <a href=
have user click the link to do the file download
You can refer to this: https://blog.gtiwari333.com/2017/01/angularjs-download-file-from-server.html
I am a beginner programmer, help with the implementation of uploading a text file via rest-api java.
I have already implemented the simplest action - unload a file from the server, here is my code:
#GetMapping(value = "/file/{filename:.+}")
public ResponseEntity<Resource> unloadFile(#PathVariable String filename) {
Resource file = storageService.loadAsResource(filename);
return ResponseEntity.ok().header(HttpHeaders.CONTENT_DISPOSITION,
"attachment; filename=\"" + file.getFilename() + "\"").body(file);
}
I can test the file unload by simply following the link!
I cannot test the upload. I find it difficult to write tests. Please tell me if I got a working code and maybe there is a better way to upload. My code upload:
#PostMapping(value = "/file")
public ResponseEntity<MultipartFile> uploadFile(MultipartFile file) {
storageService.store(file);
return ResponseEntity.ok().body(file);
}
Thank you so much!
To upload the file/files using spring boot application we use same method that we had for servlet containers. In your controller
#PostMapping("/uploadFile")
public ResponseEntity<Object> uploadFile(#RequestParam("file") MultipartFile file) {
String fileName = yourStorageService.storeFile(file);
String = ServletUriComponentsBuilder.fromCurrentContextPath()
.path("/downloadFile/")
.path(fileName)
.toUriString();
//You can even generate download links.
return new ResponseEntity<Object>(HttpStatus.Ok, "Uploaded", fileDownloadUri);
}
To download the files:
#GetMapping("/downloadFile/{fileName}")
public ResponseEntity<Resource> downloadFile(#PathVariable String fileName, HttpServletRequest request) {
// Load file as Resource from DB or local
Resource resource = fileStorageService.loadFileAsResource(fileName);
return ResponseEntity.ok()
.contentType(MediaType.parseMediaType(contentType))
.header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + resource.getFilename() + "\"")
.body(resource);
For #PostMapping(value = "/file") endpoint , its best to return a success/error status instead of returning the file,if file is larger ..it takes time to return back.
Better to return success state. 200 ok.
I'm trying to display an image in jsp injected.
I upload and I store the image in the database, but do not know how retrieve and display in jsp.
My controller:
#RequestMapping(value = "/ver2", method = RequestMethod.GET)
public void ver2(HttpSession session, HttpServletResponse response) {
OutputStream oImage;
Item item10 = itemRepository.findOne(11);
try {
byte[] photo = item10.getImagen();
response.setContentType("image/jpeg, image/jpg, image/png, image/gif");
oImage = response.getOutputStream();
oImage.write(photo);
oImage.flush();
oImage.close();
} catch (Exception e) {
e.printStackTrace();
}
}
With this code, i show a full screen, and i need inject in jsp. Any idea?
Thanks
You need to return Base64 encoded image bytes in String to your JSP page and use:
<img src="data:image/png;base64,${yourBase64EncodedBytesString}"/>
to display your image.
Use Apache Commons Codec to do Base64 encodings.
So for e.g.:
String yourBase64EncodedBytesString = new String(Base64.encodeBase64(content));
Set it for e.g. as a request attribute:
request.setAttribute("yourBase64EncodedBytesString", yourBase64EncodedBytesString);
And retrieve in JSP page:
<img src="data:image/png;base64,${requestScope['yourBase64EncodedBytesString']}"/>
I have a requirement where I need to download a PDF from the website. The PDF needs to be generated within the code, which I thought would be a combination of freemarker and a PDF generation framework like iText. Any better way?
However, my main problem is how do I allow the user to download a file through a Spring Controller?
#RequestMapping(value = "/files/{file_name}", method = RequestMethod.GET)
public void getFile(
#PathVariable("file_name") String fileName,
HttpServletResponse response) {
try {
// get your file as InputStream
InputStream is = ...;
// copy it to response's OutputStream
org.apache.commons.io.IOUtils.copy(is, response.getOutputStream());
response.flushBuffer();
} catch (IOException ex) {
log.info("Error writing file to output stream. Filename was '{}'", fileName, ex);
throw new RuntimeException("IOError writing file to output stream");
}
}
Generally speaking, when you have response.getOutputStream(), you can write anything there. You can pass this output stream as a place to put generated PDF to your generator. Also, if you know what file type you are sending, you can set
response.setContentType("application/pdf");
I was able to stream line this by using the built in support in Spring with it's ResourceHttpMessageConverter. This will set the content-length and content-type if it can determine the mime-type
#RequestMapping(value = "/files/{file_name}", method = RequestMethod.GET)
#ResponseBody
public FileSystemResource getFile(#PathVariable("file_name") String fileName) {
return new FileSystemResource(myService.getFileFor(fileName));
}
You should be able to write the file on the response directly. Something like
response.setContentType("application/pdf");
response.setHeader("Content-Disposition", "attachment; filename=\"somefile.pdf\"");
and then write the file as a binary stream on response.getOutputStream(). Remember to do response.flush() at the end and that should do it.
With Spring 3.0 you can use the HttpEntity return object. If you use this, then your controller does not need a HttpServletResponse object, and therefore it is easier to test.
Except this, this answer is relative equals to the one of Infeligo.
If the return value of your pdf framework is an byte array (read the second part of my answer for other return values) :
#RequestMapping(value = "/files/{fileName}", method = RequestMethod.GET)
public HttpEntity<byte[]> createPdf(
#PathVariable("fileName") String fileName) throws IOException {
byte[] documentBody = this.pdfFramework.createPdf(filename);
HttpHeaders header = new HttpHeaders();
header.setContentType(MediaType.APPLICATION_PDF);
header.set(HttpHeaders.CONTENT_DISPOSITION,
"attachment; filename=" + fileName.replace(" ", "_"));
header.setContentLength(documentBody.length);
return new HttpEntity<byte[]>(documentBody, header);
}
If the return type of your PDF Framework (documentBbody) is not already a byte array (and also no ByteArrayInputStream) then it would been wise NOT to make it a byte array first. Instead it is better to use:
InputStreamResource,
PathResource (since Spring 4.0) or
FileSystemResource,
example with FileSystemResource:
#RequestMapping(value = "/files/{fileName}", method = RequestMethod.GET)
public HttpEntity<byte[]> createPdf(
#PathVariable("fileName") String fileName) throws IOException {
File document = this.pdfFramework.createPdf(filename);
HttpHeaders header = new HttpHeaders();
header.setContentType(MediaType.APPLICATION_PDF);
header.set(HttpHeaders.CONTENT_DISPOSITION,
"attachment; filename=" + fileName.replace(" ", "_"));
header.setContentLength(document.length());
return new HttpEntity<byte[]>(new FileSystemResource(document),
header);
}
If you:
Don't want to load the whole file into a byte[] before sending to the response;
Want/need to send/download it via InputStream;
Want to have full control of the Mime Type and file name sent;
Have other #ControllerAdvice picking up exceptions for you (or not).
The code below is what you need:
#RequestMapping(value = "/stuff/{stuffId}", method = RequestMethod.GET)
public ResponseEntity<FileSystemResource> downloadStuff(#PathVariable int stuffId)
throws IOException {
String fullPath = stuffService.figureOutFileNameFor(stuffId);
File file = new File(fullPath);
long fileLength = file.length(); // this is ok, but see note below
HttpHeaders respHeaders = new HttpHeaders();
respHeaders.setContentType("application/pdf");
respHeaders.setContentLength(fileLength);
respHeaders.setContentDispositionFormData("attachment", "fileNameIwant.pdf");
return new ResponseEntity<FileSystemResource>(
new FileSystemResource(file), respHeaders, HttpStatus.OK
);
}
More on setContentLength(): First of all, the content-length header is optional per the HTTP 1.1 RFC. Still, if you can provide a value, it is better. To obtain such value, know that File#length() should be good enough in the general case, so it is a safe default choice.
In very specific scenarios, though, it can be slow, in which case you should have it stored previously (e.g. in the DB), not calculated on the fly. Slow scenarios include: if the file is very large, specially if it is on a remote system or something more elaborated like that - a database, maybe.
InputStreamResource
If your resource is not a file, e.g. you pick the data up from the DB, you should use InputStreamResource. Example:
InputStreamResource isr = new InputStreamResource(...);
return new ResponseEntity<InputStreamResource>(isr, respHeaders, HttpStatus.OK);
Do
Return ResponseEntity<Resource> from a handler method
Specify Content-Type
Set Content-Disposition if necessary:
filename
type
inline to force preview in a browser
attachment to force a download
Example
#Controller
public class DownloadController {
#GetMapping("/downloadPdf.pdf")
// 1.
public ResponseEntity<Resource> downloadPdf() {
FileSystemResource resource = new FileSystemResource("/home/caco3/Downloads/JMC_Tutorial.pdf");
// 2.
MediaType mediaType = MediaTypeFactory
.getMediaType(resource)
.orElse(MediaType.APPLICATION_OCTET_STREAM);
HttpHeaders headers = new HttpHeaders();
headers.setContentType(mediaType);
// 3
ContentDisposition disposition = ContentDisposition
// 3.2
.inline() // or .attachment()
// 3.1
.filename(resource.getFilename())
.build();
headers.setContentDisposition(disposition);
return new ResponseEntity<>(resource, headers, HttpStatus.OK);
}
}
Explanation
Return ResponseEntity<Resource>
When you return a ResponseEntity<Resource>, the ResourceHttpMessageConverter writes file contents
Examples of Resource implementations:
ByteArrayResource - based in byte[]
FileSystemResource - for a File or a Path
UrlResource - retrieved from java.net.URL
GridFsResource - a blob stored in MongoDB
ClassPathResource - for files in classpath, for example files from resources directory. My answer to question "Read file from resources folder in Spring Boot" explains how to locate the resource in classpath in details
Specify Content-Type explicitly:
Reason: see "FileSystemResource is returned with content type json" question
Options:
Hardcode the header
Use the MediaTypeFactory from Spring. The MediaTypeFactory maps Resource to MediaType using the /org/springframework/http/mime.types file
Use a third party library like Apache Tika
Set Content-Disposition if necessary:
About Content-Disposition header:
The first parameter in the HTTP context is either inline (default value, indicating it can be displayed inside the Web page, or as the Web page) or attachment (indicating it should be downloaded; most browsers presenting a 'Save as' dialog, prefilled with the value of the filename parameters if present).
Use ContentDisposition in application:
To preview a file in a browser:
ContentDisposition disposition = ContentDisposition
.inline()
.filename(resource.getFilename())
.build();
To force a download:
ContentDisposition disposition = ContentDisposition
.attachment()
.filename(resource.getFilename())
.build();
Use InputStreamResource carefully:
Specify Content-Length using the HttpHeaders#setContentLength method if:
The length is known
You use InputStreamResource
Reason: Spring won't write Content-Length for InputStreamResource because Spring can't determine the length of the resource. Here is a snippet of code from ResourceHttpMessageConverter:
#Override
protected Long getContentLength(Resource resource, #Nullable MediaType contentType) throws IOException {
// Don't try to determine contentLength on InputStreamResource - cannot be read afterwards...
// Note: custom InputStreamResource subclasses could provide a pre-calculated content length!
if (InputStreamResource.class == resource.getClass()) {
return null;
}
long contentLength = resource.contentLength();
return (contentLength < 0 ? null : contentLength);
}
In other cases Spring sets the Content-Length:
~ $ curl -I localhost:8080/downloadPdf.pdf | grep "Content-Length"
Content-Length: 7554270
This code is working fine to download a file automatically from spring controller on clicking a link on jsp.
#RequestMapping(value="/downloadLogFile")
public void getLogFile(HttpSession session,HttpServletResponse response) throws Exception {
try {
String filePathToBeServed = //complete file name with path;
File fileToDownload = new File(filePathToBeServed);
InputStream inputStream = new FileInputStream(fileToDownload);
response.setContentType("application/force-download");
response.setHeader("Content-Disposition", "attachment; filename="+fileName+".txt");
IOUtils.copy(inputStream, response.getOutputStream());
response.flushBuffer();
inputStream.close();
} catch (Exception e){
LOGGER.debug("Request could not be completed at this moment. Please try again.");
e.printStackTrace();
}
}
Below code worked for me to generate and download a text file.
#RequestMapping(value = "/download", method = RequestMethod.GET)
public ResponseEntity<byte[]> getDownloadData() throws Exception {
String regData = "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. It has survived not only five centuries, but also the leap into electronic typesetting, remaining essentially unchanged. It was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with desktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.";
byte[] output = regData.getBytes();
HttpHeaders responseHeaders = new HttpHeaders();
responseHeaders.set("charset", "utf-8");
responseHeaders.setContentType(MediaType.valueOf("text/html"));
responseHeaders.setContentLength(output.length);
responseHeaders.set("Content-disposition", "attachment; filename=filename.txt");
return new ResponseEntity<byte[]>(output, responseHeaders, HttpStatus.OK);
}
What I can quickly think of is, generate the pdf and store it in webapp/downloads/< RANDOM-FILENAME>.pdf from the code and send a forward to this file using HttpServletRequest
request.getRequestDispatcher("/downloads/<RANDOM-FILENAME>.pdf").forward(request, response);
or if you can configure your view resolver something like,
<bean id="pdfViewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="viewClass"
value="org.springframework.web.servlet.view.JstlView" />
<property name="order" value=”2″/>
<property name="prefix" value="/downloads/" />
<property name="suffix" value=".pdf" />
</bean>
then just return
return "RANDOM-FILENAME";
The following solution work for me
#RequestMapping(value="/download")
public void getLogFile(HttpSession session,HttpServletResponse response) throws Exception {
try {
String fileName="archivo demo.pdf";
String filePathToBeServed = "C:\\software\\Tomcat 7.0\\tmpFiles\\";
File fileToDownload = new File(filePathToBeServed+fileName);
InputStream inputStream = new FileInputStream(fileToDownload);
response.setContentType("application/force-download");
response.setHeader("Content-Disposition", "attachment; filename="+fileName);
IOUtils.copy(inputStream, response.getOutputStream());
response.flushBuffer();
inputStream.close();
} catch (Exception exception){
System.out.println(exception.getMessage());
}
}
something like below
#RequestMapping(value = "/download", method = RequestMethod.GET)
public void getFile(HttpServletResponse response) {
try {
DefaultResourceLoader loader = new DefaultResourceLoader();
InputStream is = loader.getResource("classpath:META-INF/resources/Accepted.pdf").getInputStream();
IOUtils.copy(is, response.getOutputStream());
response.setHeader("Content-Disposition", "attachment; filename=Accepted.pdf");
response.flushBuffer();
} catch (IOException ex) {
throw new RuntimeException("IOError writing file to output stream");
}
}
You can display PDF or download it examples here
If it helps anyone. You can do what the accepted answer by Infeligo has suggested but just put this extra bit in the code for a forced download.
response.setContentType("application/force-download");
In my case I'm generating some file on demand, so also url has to be generated.
For me works something like that:
#RequestMapping(value = "/files/{filename:.+}", method = RequestMethod.GET, produces = "text/csv")
#ResponseBody
public FileSystemResource getFile(#PathVariable String filename) {
String path = dataProvider.getFullPath(filename);
return new FileSystemResource(new File(path));
}
Very important is mime type in produces and also that, that name of the file is a part of the link so you has to use #PathVariable.
HTML code looks like that:
<a th:href="#{|/dbreport/files/${file_name}|}">Download</a>
Where ${file_name} is generated by Thymeleaf in controller and is i.e.: result_20200225.csv, so that whole url behing link is: example.com/aplication/dbreport/files/result_20200225.csv.
After clicking on link browser asks me what to do with file - save or open.
I had to add this to download any file
response.setContentType("application/octet-stream");
response.setHeader("Content-Disposition",
"attachment;filename="+"file.txt");
all code:
#Controller
public class FileController {
#RequestMapping(value = "/file", method =RequestMethod.GET)
#ResponseBody
public FileSystemResource getFile(HttpServletResponse response) {
final File file = new File("file.txt");
response.setContentType("application/octet-stream");
response.setHeader("Content-Disposition",
"attachment;filename="+"file.txt");
return new FileSystemResource(file);
}
}
This can be a useful answer.
Is it ok to export data as pdf format in frontend?
Extending to this, adding content-disposition as an attachment(default) will download the file. If you want to view it, you need to set it to inline.