Validator for an upload file

Question

I need a validator for an upload file, for the moment I can upload all the files but I need a check that file is less than 10 MB and only text format such as ms word, txt, ppt, excel (not executable, might be harmful). Do I have to use and libraries of java for that, or I don't know what, cause I am a junior. If anyone has any ideas that will be very nice. I have seen some other similar question and i try out but none that can help me. Ps: I am working on java spring.

Here is my code is compiled but not working is possible edit and also to check for the length.

 class FileUploader implements Receiver, SucceededListener, FailedListener, ProgressListener {
    private static final long serialVersionUID = 1L;
    public File file;
    public String filename;

    @Override
    public void updateProgress(long readBytes, long contentLength) {
        UI ui = UI.getCurrent();
        ui.access(() -> {
            progressBar.setCaption("Uploaded: " + (float) readBytes / (float) contentLength * 100 + "%");
            progressBar.setValue((float) readBytes / (float) contentLength);
            progressBar.setVisible(true);
        });
    }

    @Override
    public void uploadFailed(FailedEvent event) {
        UIHelper.showErrorNotification("File could not be uploaded");
    }

    @Override
    public void uploadSucceeded(SucceededEvent event) {
        try {           
            String savePath = "/var/ccpt_work_files/";
            Path filePath = Paths.get(savePath);            
            if (Files.exists(filePath)) {
                copyFiles("/tmp/" + event.getFilename(), savePath + event.getFilename(), savePath + event.getFilename());
            } else {
                File targetFile = new File(savePath);
                if (!targetFile.mkdirs()) {
                    UIHelper.showErrorNotification("Couldn't create dir: " + targetFile);
                } else {
                    copyFiles("/tmp/" + event.getFilename(), savePath + event.getFilename(), savePath + event.getFilename());
                }
            }
        } catch (IOException e) {
            UIHelper.showErrorNotification("File could not be uploaded");
        }
        UIHelper.showInformationNotification("File successfully uploaded");
    }

    private void copyFiles(String from, String to, String finalPath) throws IOException {
        com.google.common.io.Files.copy(new File(from), new File(to));
        uploadedFilePath = finalPath;
    }

    @Override
    public OutputStream receiveUpload(String filename, String mimeType) {
        this.filename = filename;
        FileOutputStream fos = null;
        try {
            file = new File("/tmp/" + filename);
            fos = new FileOutputStream(file);
            if (!file.exists()) {
                file.createNewFile();
            }
        } catch (final IOException e) {
            UIHelper.showErrorNotification("File could not be stored in server");
            return null;
        }
        return fos;
    }       
};

score 1 · Accepted Answer · answered Jan 17 '19 at 12:43

If you already have the File object of type java.io.File, you can just check for file size and mime type

boolean hasValidFileSize(File file, double maxFileSize) {
    double bytes = file.length();
    double megabytes = (kilobytes / 1024) / 1024;

    if (megabytes > maxFileSize) {
        return false;
    }
    return true;
}

For non harmful files, you can just check for the mime type. Look for ways on how to get the mime types for the files that you needed to be allowed and compare it with your file's mime type.

I try to do sth but as it seems i don't know how to check for mime type and compare the with the file i want to allow to upload...can you provide me a simple example @rhandom and i also edit my question have a look — Ilia Tapia, Jan 17 '19 at 15:08

Anil · Answer 2 · 2019-01-17T12:04:38.740

0

You can use this method to get the fileSize of a file.

    static String getFileSizeMegaBytes(File file) {
       return (double) file.length() / (1024 * 1024) + " mb";
    }

Refer the post to get the file type.

File tyle extension

edited Jan 17 '19 at 12:04

answered Jan 17 '19 at 11:57

Anil

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The second method has an unknown dependency – Joakim Danielson Jan 17 '19 at 12:03
I just edited and added a SO link. It has multiple ways to get mimetype. – Anil Jan 17 '19 at 12:05
1

Ok i will try thanks a lot, what about the harmful files? – Ilia Tapia Jan 17 '19 at 12:25
1

I just the link and is very helpful, i will try one of them. – Ilia Tapia Jan 17 '19 at 12:31
Determining whether a file is harmful is always tricy and you can accomplish in multiple ways. Consider that as seperate problem. – Anil Jan 17 '19 at 12:38
I am glad it helped you. – Anil Jan 17 '19 at 12:38

Validator for an upload file

2 Answers2