Get file extension from uploaded file

Question

Here my requirement is to upload the file and to store it in the disk. I have no problem in storing it in disk, but getting the extension of the file. The problem is when I clic

Answer 1

I used Jquery fileupload in client side.

And at my JS file ,

function doUploadPhoto(seq) {
$('#fileupload').fileupload({
    url : 'news/upload.html?s=' + seq,
    sequentialUploads : true,
    disableImageResize : false,
    imageMaxWidth : 1024,
    imageMaxHeight : 1024,
    previewCrop : true,
    dropZone : $("#dropZone"),
    acceptFileTypes : /(\.|\/)(gif|jpe?g|png)$/i,
    progress : function(e, data) {
        if (data.context) {
            var progress = data.loaded / data.total * 100;
            progress = Math.floor(progress);
            $('.progress').attr('aria-valuenow', progress);
            $('.progress').css('display', 'block');
            $('.bar').css('width', progress + '%');
        }
    },
    progressall : function(e, data) {
        var progress = data.loaded / data.total * 100;
        progress = Math.floor(progress);
        $('.progressall').attr('aria-valuenow', progress);
        $('.progressall').css('display', 'block');
        $('.allbar').css('width', progress + '%');
        if (progress > 20) {
            $('.allbar').text(progress + '% Completed');
        }
    },
    stop: function (e) {
        return;
    }
});
}

Handle your specific request for image upload (I used Spring).

@RequestMapping(value = "/news/upload.html", method = RequestMethod.POST)
public final void uploadNewsPhoto(final HttpServletRequest request, final HttpServletResponse response)
        throws Exception {
    doUploadNewsPhoto(request, getSessionFileItems(request));
}

for upload image

public final synchronized String doUploadNewsPhoto(final HttpServletRequest request,
        final List<FileItem> sessionFiles) throws UploadActionException {

    try {
        List<Map<String, Object>> ret = new ArrayList<Map<String, Object>>();
        for (FileItem item : sessionFiles) {
            if (!item.isFormField()) {
                try {
                    // get news sequence for save it's images
                    Long seq = Long.parseLong(request.getParameter("s"));
                    Map<String, Object> res = newsPhotoBiz.saveToFile(seq, item, SecuritySession.getLoginUserSeq());

                    res.put("name", item.getName());
                    res.put("size", item.getSize());
                    ret.add(res);
                }
                catch (Exception e) {
                    log.error("Error, can't upload news photo file, name:" + item.getName(), e);
                }
            }
        }

        // Remove files from session because we have a copy of them
        removeSessionFileItems(request);

        Map<String, Object> json = new HashMap<String, Object>();
        json.put("files", ret);
        JSONObject obj = (JSONObject) JSONSerializer.toJSON(json);
        // return to client side about uploaded images info
        return obj.toString();
    }
    catch (Exception e) {
        log.error("Error, when upload news photo file", e);
        throw new UploadActionException(e);
    }
}

for save image

public final Map<String, Object> saveToFile(final Long newsSeq, final FileItem item, final Long loginUserSeq)
        throws BusinessException {
    String staticDir = System.getProperty("staticDir");

    Date today = new Date();
    SimpleDateFormat fmtYMD = new SimpleDateFormat("/yyyyMMdd");
    SimpleDateFormat fmtHMS = new SimpleDateFormat("HHmmssS");

    String saveDir = "data/news" + fmtYMD.format(today);
    String format = ".jpg";
    try {
        format = item.getName().substring(item.getName().lastIndexOf("."), item.getName().length());
    }
    catch (Exception e) {
      format = ".jpg";
    }

    try {
        String fileName = newsSeq + "_" + fmtHMS.format(today) + format;

        NewsPhotoBean bean = new NewsPhotoBean();
        bean.setNewsSeq(newsSeq);
        bean.setFile(saveDir + "/" + fileName);
           // save image infos in database and return it's sequence
        Long photoSeq = newsPhotoService.add(bean, loginUserSeq);

        // Save image in specify location
        String filePath = staticDir + "/" + saveDir;
        FileSupport.saveFile(filePath, fileName, item);

        Map<String, Object> ret = new HashMap<String, Object>();
        ret.put("seq", newsSeq);
        ret.put("photoSeq", photoSeq);
        ret.put("path", saveDir + "/" + fileName);
        ret.put("ext", format.substring(1));

       //client side may need uploaded images info
        return ret;
    }
    catch (Exception e) {
        throw new BusinessException("Error occur when save file. newsSeq : " + newsSeq, e);
    }
}

for write image

// Save Image by FileItem that gets from Image Upload
public static String saveFile(final String filePath, final String fileName, final FileItem item) throws Exception {
    File file = new File(filePath);
    file.setExecutable(true, false);
    file.setWritable(true, false);

    if (!file.exists()) {
        file.mkdirs();
    }

    File imageFile = new File(file, fileName);
    item.write(imageFile);
    item.setFieldName(filePath + fileName);

    return item.toString();
}

Answer 2

To get the extension of a file from servlet upload, your form enctype should be "multipart/form-data" Example upload form:

    <form  action="CheatQuizUpload" method="POST" target="miao" enctype="multipart/form-data">
                Upload your file<br>
                <input required type="file" name="file">
                <button type="submit" class="btn btn-success">Submit</button>
                <br>
            </form>

On the server-side, the parameter name of the file will correspond to the "name" attribute of the input.

        //...other request handling code 
    Part filePart = request.getPart("file");/*"name" attribute of your input*/
        String fileName = filePart.getSubmittedFileName();//full name of file submitted
        String[] fileNameSplit = fileName.split(".");//split between name and extension
        String extension = fileNameSplit[fileNameSplit.length-1];//get the extension part of the file name

Answer 3

This worked for me

Part filePart = request.getPart("input-file"); 
String type=filePart.getContentType();
type="."+type.substring(type.lastIndexOf("/")+1);

Answer 4

I have found the solution for this. Actually this is of Play framework. I got the file using following code.

MultipartFormData body = request().body().asMultipartFormData();
FilePart fileInput = body.getFile("fileInput");
File file = fileInput.getFile();

I tried to get the name of file using this File object (which is used to store in a tmp location). But I missed to notice that FilePart object contains all file details that was uploaded. Then I figured it out.

fileInput.getFilename() gives me the uploaded file name with extension. It solves my problem.

Thanks for Cataclysm for helping me out. Surely the one he gave is the best answer for other framework like Struts/Spring or core servlets.