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.FileUpload

All Implemented Interfaces:

HasChangeHandlers, HasAttachHandlers, HasHandlers, EventListener, HasName, IsWidget

public class FileUpload
extends Widget
implements HasName, HasChangeHandlers

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);
  }
}

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

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 java.lang.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 java.lang.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.

Returns:

true if the widget is enabled

onBrowserEvent

public void onBrowserEvent(Event event)

Description copied from interface: EventListener

Fired whenever a browser event is received.

Specified by:

onBrowserEvent in interface EventListener

Overrides:

onBrowserEvent in class Widget

Parameters:

event - the event received

setEnabled

public void setEnabled(boolean enabled)

Sets whether this widget is enabled.

Parameters:

enabled - true to enable the widget, false to disable it

setName

public void setName(java.lang.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