How to upload,display,download and delete files using spring mvc - spring

Question

Hi am trying to do operations like uploading a file,displaying a file,downloading a file and deleting a file using spring mvc i got success in uploading file and deleting file all operations working fine but then whats happening is when i do uploading the uploaded file or image displaying or downloading twice and getting
java.lang.IllegalStateException: getOutputStream() has already been called for this response
<form method="post" action="doUpload" enctype="multipart/form-data">
<table border="0">
<tr>
<td>Pick file #1:</td>
<td><input type="file" name="fileUpload" size="50" /></td>
</tr>
<tr>
<td>Pick file #2:</td>
<td><input type="file" name="fileUpload" size="50" /></td>
</tr>
<tr>
<td colspan="2" align="center"><input type="submit" value="Upload" /></td>
</tr>
</table>
</form>
<table border="1" bgcolor="black" width="600px">
<tr style="background-color: teal; color: white; text-align: center;"
height="40px">
<td>File Name</td>
<td>Image</td>
<td>Download</td>
<td>Delete</td>
</tr>
<c:forEach items="${employeeList}" var="user">
<tr style="background-color: white; color: black; text-align: center;"
height="30px">
<td><c:out value="${user.fileName}" /></td>
<td><img src="show?id=${user.id}" /></td>
<td>Download</td>
<td>Delete</td>
</tr>
</c:forEach>
</table>
#Controller
#RequestMapping("/")
public class RegistrationController {
#Autowired
private IRegistrationService registerService;
#RequestMapping(value = "/saveParentAndStudentFromAdmin", method = RequestMethod.POST)
public ModelAndView saveParentAndStudentByAdmin(
#ModelAttribute Student student,
#RequestParam CommonsMultipartFile[] fileUpload) {
if (fileUpload != null && fileUpload.length > 0) {
for (CommonsMultipartFile aFile : fileUpload) {
System.out.println("Saving file: "
+ aFile.getOriginalFilename());
student.setFileName(aFile.getOriginalFilename());
student.setFileType(aFile.getContentType());
student.setData(aFile.getBytes());
registerService.saveParentAndStudentByAdmin(student);
}
}
java.util.List<Student> uploadedFiles = registerService.findAllFiles();
return new ModelAndView("StudentEnrollmentFromAdmin", "employeeList",
uploadedFiles);
}
#RequestMapping("delete")
public ModelAndView deleteUser(#RequestParam int id) {
registerService.deleteRow(id);
java.util.List<Student> uploadedFiles = registerService.findAllFiles();
return new ModelAndView("StudentEnrollmentFromAdmin", "employeeList",
uploadedFiles);
}
#RequestMapping("show")
public ModelAndView displayImage(#RequestParam int id,
HttpServletResponse response, HttpServletRequest request) {
System.out.println("Id to display image: " + id);
Student item = registerService.get(id);
response.setContentType("image/jpeg, image/jpg, image/png, image/gif");
try {
response.getOutputStream().write(item.getData());
} catch (IOException e) {
e.printStackTrace();
}
try {
response.getOutputStream().close();
} catch (IOException e) {
e.printStackTrace();
}
return new ModelAndView("StudentEnrollmentFromAdmin");
}
#RequestMapping("downalod")
public ModelAndView downloadFile(#RequestParam int id,
HttpServletResponse response, HttpServletRequest request) {
System.out.println("Id to download: " + id);
Student student = registerService.get(id);
response.setContentType(student.getFileType());
response.setContentLength(student.getData().length);
response.setHeader("Content-Disposition", "attachment; filename=\""
+ student.getFileName() + "\"");
try {
FileCopyUtils.copy(student.getData(), response.getOutputStream());
} catch (IOException e) {
e.printStackTrace();
}
java.util.List<Student> uploadedFiles = registerService.findAllFiles();
return new ModelAndView("StudentEnrollmentFromAdmin", "employeeList",
uploadedFiles);
}
}

Answer 1

If I correctly understood your question you may do something like this:
public ResponseEntity<InputStreamResource> getFile(#PathVariable("idForm") String idForm)
{
try
{
Student item = registerService.get(id);
HttpHeaders respHeaders = new HttpHeaders();
//Change it with your real content type
MediaType mediaType = new MediaType("img","jpg");
respHeaders.setContentType(mediaType);
respHeaders.setContentLength(file.length());
//I suppose you have a method "getFileName"
//By using attachment you download the file; by using inline you should see the image in the browser
respHeaders.setContentDispositionFormData("attachment", item.getFileName());
InputStreamResource isr = new InputStreamResource(new ByteArrayOutputStream(item.getData()));
return new ResponseEntity<InputStreamResource>(isr, respHeaders, HttpStatus.OK);
}
catch (Exception e)
{
String message = "Error; "+e.getMessage();
logger.error(message, e);
return new ResponseEntity<InputStreamResource>(HttpStatus.INTERNAL_SERVER_ERROR);
}
}
Angelo