Spring error: IllegalStateException: Cannot call sendRedirect() after the response has been committed and getOutputStream() has already been called - spring

Question

I have got an error when I try to download a zipped file using Spring boot and spring MVC:
Errors:
SEVERE: Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.lang.IllegalStateException: Cannot call sendRedirect() after the response has been committed] with root cause
java.lang.IllegalStateException: Cannot call sendRedirect() after the response has been committed
SEVERE: Servlet.service() for servlet dispatcherServlet threw exception
java.lang.IllegalStateException: getOutputStream() has already been called for this response
Basically, my app is loading a file, zipping it and download the new zip file.
This is my application Controller:
#Controller
public class ApplicationController {
public String fileZipped;
public String inputFile;
#RequestMapping(method = RequestMethod.GET, value = "/uploadForm")
public String provideUploadInfo() {
return "uploadForm";
}
#RequestMapping(method = RequestMethod.POST, value = "/")
public String handleFileUpload(#RequestParam("file") MultipartFile file,
RedirectAttributes redirectAttributes,
HttpServletResponse downloadResponse) {
if (!file.isEmpty()) {
try {
inputFile = file.getOriginalFilename();
BufferedOutputStream stream = new BufferedOutputStream(
new FileOutputStream(new File(Application.UPLOAD_DIR + "/" + inputFile)));
FileCopyUtils.copy(file.getInputStream(), stream);
stream.close();
redirectAttributes.addFlashAttribute("message",
"You successfully uploaded " + file.getOriginalFilename() + "!");
FileUtils.copyDirectory(Application.UPLOAD_DIR, Application.OUTPUT_FOLDER);
FileUtils.cleanDirectory(new File(Application.UPLOAD_DIR));
}
catch (Exception e) {
redirectAttributes.addFlashAttribute("message",
"You failed to upload " + file.getOriginalFilename() + " => " + e.getMessage());
}
}
else {
redirectAttributes.addFlashAttribute("message",
"You failed to upload " + file.getOriginalFilename() + " because the file was empty");
}
return "redirect:/zipFiles";
}
#RequestMapping(value = "/download")
public String handleFileDownload(HttpServletResponse downloadResponse) throws IOException {
InputStream inputStream = null;
OutputStream outStream = null;
try {
if ( fileZipped!=null && Files.exists(Paths.get(fileZipped))) {
inputStream = new FileInputStream(fileZipped);
downloadResponse.setContentType(fileZipped);
downloadResponse.addHeader("Content-Disposition", "attachment; filename=" + Paths.get(fileZipped).getFileName().toString());
outStream = downloadResponse.getOutputStream();
org.apache.commons.io.IOUtils.copy(inputStream, outStream);
downloadResponse.flushBuffer();
}
} catch (IOException e) {
throw new RuntimeException("IOError writing file to output stream");
} finally {
if (inputStream != null) inputStream.close();
if (outStream != null) outStream.close();
}
return "redirect:/uploadForm";
}
#RequestMapping(value="/zipFiles")
public String handleFileZip() throws IOException {
if(inputFile!=null) {
fileZipped = zipFiles(Application.OUTPUT_FOLDER, inputFile);
}
return "redirect:/download";
}
private String zipFiles(String folder, String zipFileName) throws IOException {
String zipFile = folder + "/" + FilenameUtils.removeExtension(zipFileName) + ".zip";
FileOutputStream fileOutputstream = new FileOutputStream(zipFile);
ZipOutputStream zipOutputStream = new ZipOutputStream(new BufferedOutputStream(fileOutputstream));
File []filesArray = new File(folder).listFiles();
for (File file : filesArray){
if (!FilenameUtils.getExtension(file.getAbsolutePath()).equals("zip")) {
byte[] buffer = new byte[1024];
FileInputStream fileInputStream = new FileInputStream(file);
zipOutputStream.putNextEntry(new ZipEntry(file.getName()));
int length;
while ((length = fileInputStream.read()) > 0) {
zipOutputStream.write(buffer, 0, length);
}
zipOutputStream.closeEntry();
fileInputStream.close();
}
}
zipOutputStream.close();
return zipFile;
}
I do no know why that is happening if I am closing the input and output streams.
Thanks you very much for your help.

Answer 1

The problem is with the redirect. Instead of
return "redirect:/uploadForm";
return the view name.
return "/uploadForm";