Java Doc for SFileChooser.java in  » Swing-Library » wings3 » org » wings » Java Source Code / Java DocumentationJava Source Code and Java Documentation

The uploaded file is stored temporarily in the filesystem of the server with a unique name, so that uploaded files with the same filename do not clash. You can access this internal name with the SFileChooser.getFileDir() and SFileChooser.getFileId() methods. The user provided filename can be queried with the SFileChooser.getFileName() method.

Since the file is stored temporarily in the filesystem, you should File.delete it, when you are done with it. However, if you don't delete the file yourself, it is eventually being removed by the Java garbage collector, if you haven't renamed it (see SFileChooser.getFile() ).

The form, you add this SFileChooser to, needs to have the encoding type multipart/form-data set (form. SForm.setEncodingType(String) setEncodingType("multipart/form-data") ). This is handled by the form. You can explicitly set it via the above method, though, in order to increase speed.

You can limit the size of files to be uploaded, so it is hard to make a denial-of-service (harddisk, bandwidth) attack from outside to your server. You can modify the maximum content length to be posted in org.wings.session.Session.setMaxContentLength(int) . This is 64 kByte by default, so you might want to change this in your application.

The SFileChooser notifies the form if something has gone wrong with uploading a file.

Szenario Files that are too big to be uploaded are blocked very early in the upload-process (if you are curious: this is done in org.wings.session.MultipartRequest ). At that time, only a partial input is read, the rest is discarded to thwart denial of service attacks. Since we read only part of the input, we cannot make sure, that all parameters are gathered from the input, thus we cannot just deliver the events contained, since they might be incomplete. However, the file chooser needs to be informed, that something went wrong as to present an error message to the user. So in that case, only one event is delivered to the enclosing form, that contains this SFileChooser.

Note, that in this case, this will not trigger the action listener that you might have added to the submit-button. This means, that you always should add your action listener to the SForm ( SForm.addActionListener(java.awt.event.ActionListener) ), not the submit button.
author:
   Holger Engels
author:
   Henner Zeller

The file returned here will delete itself if you loose the reference to it and it is garbage collected to avoid filling up the filesystem (This doesn't mean, that you shouldn't be a good programmer and delete the file yourself, if you don't need it anymore :-). If you rename() the file to use it somewhere else, it is regarded not temporary anymore and thus will not be removed from the filesystem. a File to access the content of the uploaded file.
throws:
  IOException - if something went wrong with the upload (mostlikely, the maximum allowed filesize is exceeded, seeorg.wings.session.Session.setMaxContentLength(int))org.wings.SFileChooser.getSelectedFile

The file returned here will delete itself if you loose the reference to it and it is garbage collected to avoid filling up the filesystem (This doesn't mean, that you shouldn't be a good programmer and delete the file yourself, if you don't need it anymore :-). If you rename() the file to use it somewhere else, it is regarded not temporary anymore and thus will not be removed from the filesystem. a File to access the content of the uploaded file.
throws:
  IOException - if something went wrong with the upload (mostlikely, the maximum allowed filesize is exceeded, seeorg.wings.session.Session.setMaxContentLength(int))

In any case, you hould check the result, since you cannot assume, that the browser actually does filter. Worse, browsers may not guess the correct type so users cannot upload a file even if it has the correct type. So, bottomline, it is generally a good idea to let the file name filter untouched, unless you know bugs of the browser at the other end of the wire...
Parameters:
  mimeFilter - the mime type to be filtered.