Package com.google.gwt.user.client.ui

Class FileUpload

java.lang.Object
com.google.gwt.user.client.ui.UIObject
com.google.gwt.user.client.ui.Widget
com.google.gwt.user.client.ui.FocusWidget
com.google.gwt.user.client.ui.FileUpload
All Implemented Interfaces:
HasAllDragAndDropHandlers, HasAllFocusHandlers, HasAllGestureHandlers, HasAllKeyHandlers, HasAllMouseHandlers, HasAllTouchHandlers, HasBlurHandlers, HasChangeHandlers, HasClickHandlers, HasDoubleClickHandlers, HasDragEndHandlers, HasDragEnterHandlers, HasDragHandlers, HasDragLeaveHandlers, HasDragOverHandlers, HasDragStartHandlers, HasDropHandlers, HasFocusHandlers, HasGestureChangeHandlers, HasGestureEndHandlers, HasGestureStartHandlers, HasKeyDownHandlers, HasKeyPressHandlers, HasKeyUpHandlers, HasMouseDownHandlers, HasMouseMoveHandlers, HasMouseOutHandlers, HasMouseOverHandlers, HasMouseUpHandlers, HasMouseWheelHandlers, HasTouchCancelHandlers, HasTouchEndHandlers, HasTouchMoveHandlers, HasTouchStartHandlers, HasAttachHandlers, HasHandlers, EventListener, Focusable, HasEnabled, HasFocus, HasName, HasVisibility, IsWidget, SourcesClickEvents, SourcesFocusEvents, SourcesKeyboardEvents, SourcesMouseEvents
public class FileUpload extends FocusWidget implements HasName, HasChangeHandlers, HasEnabled
A widget that wraps the HTML <input type='file'> element. This widget must be used with FormPanel if it is to be submitted to a server.

Example

public class FormPanelExample implements EntryPoint {

  public void onModuleLoad() {
    // Create a FormPanel and point it at a service.
    final FormPanel form = new FormPanel();
    form.setAction("/myFormHandler");

    // Because we're going to add a FileUpload widget, we'll need to set the
    // form to use the POST method, and multipart MIME encoding.
    form.setEncoding(FormPanel.ENCODING_MULTIPART);
    form.setMethod(FormPanel.METHOD_POST);

    // Create a panel to hold all of the form widgets.
    VerticalPanel panel = new VerticalPanel();
    form.setWidget(panel);

    // Create a TextBox, giving it a name so that it will be submitted.
    final TextBox tb = new TextBox();
    tb.setName("textBoxFormElement");
    panel.add(tb);

    // Create a ListBox, giving it a name and some values to be associated with
    // its options.
    ListBox lb = new ListBox();
    lb.setName("listBoxFormElement");
    lb.addItem("foo", "fooValue");
    lb.addItem("bar", "barValue");
    lb.addItem("baz", "bazValue");
    panel.add(lb);

    // Create a FileUpload widget.
    FileUpload upload = new FileUpload();
    upload.setName("uploadFormElement");
    panel.add(upload);

    // Add a 'submit' button.
    panel.add(new Button("Submit", new ClickHandler() {
      public void onClick(ClickEvent event) {
        form.submit();
      }
    }));

    // Add an event handler to the form.
    form.addSubmitHandler(new FormPanel.SubmitHandler() {
      public void onSubmit(SubmitEvent event) {
        // This event is fired just before the form is submitted. We can take
        // this opportunity to perform validation.
        if (tb.getText().length() == 0) {
          Window.alert("The text box must not be empty");
          event.cancel();
        }
      }
    });
    form.addSubmitCompleteHandler(new FormPanel.SubmitCompleteHandler() {
      public void onSubmitComplete(SubmitCompleteEvent event) {
        // When the form submission is successfully completed, this event is
        // fired. Assuming the service returned a response of type text/html,
        // we can get the result text here (see the FormPanel documentation for
        // further explanation).
        Window.alert(event.getResults());
      }
    });

    RootPanel.get().add(form);
  }
}

CSS Style Rules

.gwt-FileUpload {}

NOTICE about styling

The developer should be aware that most browsers do not allow styling many properties of the rendered input-file element because of security restrictions.
You can style certain properties like position, visibility, opacity, etc. But size, color, backgrounds etc. will not work either using css or calling widget methods like setSize().

  • Constructor Details

    • FileUpload

      public FileUpload()
      Constructs a new file upload widget.

    • FileUpload

      protected FileUpload(Element element)
      This constructor may be used by subclasses to explicitly use an existing element. This element must be an <input> element whose type is 'file'.
      Parameters:
      element - the element to be used

  • Method Details

    • wrap

      public static FileUpload wrap(Element element)
      Creates a FileUpload widget that wraps an existing <input type='file'> element. This element must already be attached to the document. If the element is removed from the document, you must call RootPanel.detachNow(Widget).
      Parameters:
      element - the element to be wrapped

    • addChangeHandler

      public HandlerRegistration addChangeHandler(ChangeHandler handler)
      Description copied from interface: HasChangeHandlers
      Adds a ChangeEvent handler.
      Specified by:
      addChangeHandler in interface HasChangeHandlers
      Parameters:
      handler - the change handler
      Returns:
      HandlerRegistration used to remove this handler

    • getFilename

      public String getFilename()
      Gets the filename selected by the user. This property has no mutator, as browser security restrictions preclude setting it.
      Returns:
      the widget's filename

    • getName

      public String getName()
      Description copied from interface: HasName
      Gets the widget's name.
      Specified by:
      getName in interface HasName
      Returns:
      the widget's name

    • isEnabled

      public boolean isEnabled()
      Gets whether this widget is enabled.
      Specified by:
      isEnabled in interface HasEnabled
      Overrides:
      isEnabled in class FocusWidget
      Returns:
      true if the widget is enabled

    • setEnabled

      public void setEnabled(boolean enabled)
      Sets whether this widget is enabled.
      Specified by:
      setEnabled in interface HasEnabled
      Overrides:
      setEnabled in class FocusWidget
      Parameters:
      enabled - true to enable the widget, false to disable it

    • setName

      public void setName(String name)
      Description copied from interface: HasName
      Sets the widget's name.
      Specified by:
      setName in interface HasName
      Parameters:
      name - the widget's new name

    • click

      public void click()
      Programmatic equivalent of the user clicking the button, opening the file selection browser.

      NOTE: in certain browsers programmatic click is disabled if the element display is none, for instance in webkit you have to move the element off screen.