Spring MVC File Upload Help

Question

I have been integrating spring into an application, and have to redo a file upload from forms. I am aware of what Spring MVC has to offer and what I need to do to configure

Answer 1

This is what i prefer while making uploads.I think letting spring to handle file saving, is the best way. Spring does it with its MultipartFile.transferTo(File dest) function.

import java.io.File;
import java.io.IOException;

import javax.servlet.http.HttpServletResponse;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.multipart.MultipartFile;

@Controller
@RequestMapping("/upload")
public class UploadController {

    @ResponseBody
    @RequestMapping(value = "/save")
    public String handleUpload(
            @RequestParam(value = "file", required = false) MultipartFile multipartFile,
            HttpServletResponse httpServletResponse) {

        String orgName = multipartFile.getOriginalFilename();

        String filePath = "/my_uploads/" + orgName;
        File dest = new File(filePath);
        try {
            multipartFile.transferTo(dest);
        } catch (IllegalStateException e) {
            e.printStackTrace();
            return "File uploaded failed:" + orgName;
        } catch (IOException e) {
            e.printStackTrace();
            return "File uploaded failed:" + orgName;
        }
        return "File uploaded:" + orgName;
    }
}

Answer 2

Use the below controller class for processing the file upload.

@Controller
public class FileUploadController {

  @Autowired
  private FileUploadService uploadService;

  @RequestMapping(value = "/fileUploader", method = RequestMethod.GET)
  public String home() {
    return "fileUploader";
  }

  @RequestMapping(value = "/upload", method = RequestMethod.POST)
  public @ResponseBody List<UploadedFile> upload(MultipartHttpServletRequest request, HttpServletResponse response) throws IOException {

    // Getting uploaded files from the request object
    Map<String, MultipartFile> fileMap = request.getFileMap();

    // Maintain a list to send back the files info. to the client side
    List<UploadedFile> uploadedFiles = new ArrayList<UploadedFile>();

    // Iterate through the map
    for (MultipartFile multipartFile : fileMap.values()) {

      // Save the file to local disk
      saveFileToLocalDisk(multipartFile);

      UploadedFile fileInfo = getUploadedFileInfo(multipartFile);

      // Save the file info to database
      fileInfo = saveFileToDatabase(fileInfo);

      // adding the file info to the list
      uploadedFiles.add(fileInfo);
    }

    return uploadedFiles;
  }

  @RequestMapping(value = {"/listFiles"})
  public String listBooks(Map<String, Object> map) {

    map.put("fileList", uploadService.listFiles());

    return "listFiles";
  }

  @RequestMapping(value = "/getdata/{fileId}", method = RequestMethod.GET)
  public void getFile(HttpServletResponse response, @PathVariable Long fileId) {

    UploadedFile dataFile = uploadService.getFile(fileId);

    File file = new File(dataFile.getLocation(), dataFile.getName());

    try {
      response.setContentType(dataFile.getType());
      response.setHeader("Content-disposition", "attachment; filename=\"" + dataFile.getName() + "\"");

      FileCopyUtils.copy(FileUtils.readFileToByteArray(file), response.getOutputStream());


    } catch (IOException e) {
      e.printStackTrace();
    }
  }


  private void saveFileToLocalDisk(MultipartFile multipartFile) throws IOException, FileNotFoundException {

    String outputFileName = getOutputFilename(multipartFile);

    FileCopyUtils.copy(multipartFile.getBytes(), new FileOutputStream(outputFileName));
  }

  private UploadedFile saveFileToDatabase(UploadedFile uploadedFile) {
    return uploadService.saveFile(uploadedFile);
  }

  private String getOutputFilename(MultipartFile multipartFile) {
    return getDestinationLocation() + multipartFile.getOriginalFilename();
  }

  private UploadedFile getUploadedFileInfo(MultipartFile multipartFile) throws IOException {

    UploadedFile fileInfo = new UploadedFile();
    fileInfo.setName(multipartFile.getOriginalFilename());
    fileInfo.setSize(multipartFile.getSize());
    fileInfo.setType(multipartFile.getContentType());
    fileInfo.setLocation(getDestinationLocation());

    return fileInfo;
  }

  private String getDestinationLocation() {
    return "Drive:/uploaded-files/";
  }
}

Answer 3

but what none of these tutorials explain is correct/best practice methods on how/what is to be done to actually handle the file once you have it

The best practice depends on what you are trying to do. Usually i use some AOP to post-proccessing the uploaded file. Then you can use FileCopyUtils to store your uploaded file

@Autowired
@Qualifier("commandRepository")
private AbstractRepository<Command, Integer> commandRepository;

protected ModelAndView onSubmit(...) throws ServletException, IOException {
    commandRepository.add(command);
}

AOP is described as follows

@Aspect
public class UploadedFileAspect {

    @After("execution(* br.com.ar.CommandRepository*.add(..))")
    public void storeUploadedFile(JoinPoint joinPoint) {
        Command command = (Command) joinPoint.getArgs()[0];

        byte[] fileAsByte = command.getFile();
        if (fileAsByte != null) {
            try {
                FileCopyUtils.copy(fileAsByte, new File("<SET_UP_TARGET_FILE_RIGHT_HERE>"));
            } catch (IOException e) {
                /**
                  * log errors
                  */
            }
        }

    }

Do not forget enable aspect (update schema to Spring 3.0 if needed) Put on the classpath aspectjrt.jar and aspectjweaver.jar (<SPRING_HOME>/lib/aspectj) and

<beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xmlns:aop="http://www.springframework.org/schema/aop"
      xsi:schemaLocation="http://www.springframework.org/schema/beans
                          http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
                          http://www.springframework.org/schema/aop
                          http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">
    <aop:aspectj-autoproxy />
    <bean class="br.com.ar.aop.UploadedFileAspect"/>