UICommand (Java EE 5 SDK)

javax.faces.component Class UICommand

java.lang.Object
  javax.faces.component.UIComponent
      javax.faces.component.UIComponentBase
          javax.faces.component.UICommand

所有已实现的接口:

ActionSource, ActionSource2, StateHolder

直接已知子类:

HtmlCommandButton, HtmlCommandLink

public class UICommand

extends UIComponentBase

implements ActionSource2

UICommand is a UIComponent that represents a user interface component which, when activated by the user, triggers an application specific "command" or "action". Such a component is typically rendered as a push button, a menu item, or a hyperlink.

When the decode() method of this UICommand, or its corresponding Renderer, detects that this control has been activated, it will queue an ActionEvent. Later on, the broadcast() method will ensure that this event is broadcast to all interested listeners.

Listeners will be invoked in the following order:

1. ActionListeners, in the order in which they were registered.
2. The "actionListener" MethodExpression (which will cover the "actionListener" that was set as a MethodBinding).
3. The default ActionListener, retrieved from the Application - and therefore, any attached "action" MethodExpression.

By default, the rendererType property must be set to "javax.faces.Button". This value can be changed by calling the setRendererType() method.

COMPONENT_TYPE

public static final String COMPONENT_TYPE

The standard component type for this component.

另请参见:

常量字段

COMPONENT_FAMILY

public static final String COMPONENT_FAMILY

The standard component family for this component.

另请参见:

常量字段

UICommand

public UICommand()

Create a new UICommand instance with default property values.

getFamily

public String getFamily()

Description copied from class: UIComponent

Return the identifier of the component family to which this component belongs. This identifier, in conjunction with the value of the rendererType property, may be used to select the appropriate Renderer for this component instance.

规范说明:

getFamily in class UIComponent

getAction

public MethodBinding getAction()

Deprecated. This has been replaced by getActionExpression().

If the implementing class also implements ActionSource2, the implementation of this method must call through to ActionSource2.getActionExpression() and examine the result. If the result came from a previous call to ActionSource.setAction(javax.faces.el.MethodBinding), extract the MethodBinding from it and return it. Otherwise, wrap the returned MethodExpression in a MethodBinding implementation, and return it.

If the implementing class does not implement ActionSource2, return the MethodBindingpointing at the application action to be invoked, if this UIComponent is activated by the user, during the Apply Request Values or Invoke Application phase of the request processing lifecycle, depending on the value of the immediate property.

规范说明:

getAction in interface ActionSource

setAction

public void setAction(MethodBinding action)

Deprecated. This has been replaced by setActionExpression(javax.el.MethodExpression).

If the implementing class also implements ActionSource2, the implementation of this method must wrap the argument action in a class that implements MethodExpression and call through to ActionSource2.setActionExpression(javax.el.MethodExpression), passing the wrapped action.

If the implementing class does not implement ActionSource2, set the MethodBinding pointing at the appication action to be invoked, if this UIComponent is activated by the user, during the Apply Request Values or Invoke Application phase of the request processing lifecycle, depending on the value of the immediate property.

Any method referenced by such an expression must be public, with a return type of String, and accept no parameters.

规范说明:

setAction in interface ActionSource

参数:

action - The new MethodBinding expression

getActionListener

public MethodBinding getActionListener()

Deprecated. Use getActionListeners() instead.

If ActionSource.setActionListener(javax.faces.el.MethodBinding) was not previously called for this instance, this method must return null. If it was called, this method must return the exact MethodBinding instance that was passed to ActionSource.setActionListener(javax.faces.el.MethodBinding).

The method to be invoked, if this UIComponent is activated by the user, will be called during the Apply Request Values or Invoke Application phase of the request processing lifecycle, depending upon the value of the immediate property.

规范说明:

getActionListener in interface ActionSource

setActionListener

public void setActionListener(MethodBinding actionListener)

Deprecated. This has been replaced by addActionListener(javax.faces.event.ActionListener).

Wrap the argument actionListener in an implementation of ActionListener and store it in the internal data structure that backs the ActionSource.getActionListeners() method, taking care to over-write any instance that was stored by a previous call to setActionListener.

Any method referenced by such an expression must be public, with a return type of void, and accept a single parameter of type ActionEvent.

规范说明:

setActionListener in interface ActionSource

参数:

actionListener - The new method binding expression

isImmediate

public boolean isImmediate()

Description copied from interface: ActionSource

Return a flag indicating that the default ActionListener provided by the JavaServer Faces implementation should be executed immediately (that is, during Apply Request Values phase of the request processing lifecycle), rather than waiting until the Invoke Application phase. The default value for this property must be false.

规范说明:

isImmediate in interface ActionSource

setImmediate

public void setImmediate(boolean immediate)

Description copied from interface: ActionSource

Set the "immediate execution" flag for this UIComponent.

规范说明:

setImmediate in interface ActionSource

参数:

immediate - The new immediate execution flag

getValue

public Object getValue()

Returns the value property of the UICommand. This is most often rendered as a label.

setValue

public void setValue(Object value)

Sets the value property of the UICommand. This is most often rendered as a label.

参数:

value - the new value

getActionExpression

public MethodExpression getActionExpression()

Description copied from interface: ActionSource2

Return the MethodExpression pointing at the application action to be invoked, if this UIComponent is activated by the user, during the Apply Request Values or Invoke Application phase of the request processing lifecycle, depending on the value of the immediate property.

Note that it's possible that the returned MethodExpression is just a wrapper around a MethodBinding instance whith was set by a call to ActionSource.setAction(javax.faces.el.MethodBinding). This makes it possible for the default ActionListener to continue to work properly with older components.

规范说明:

getActionExpression in interface ActionSource2

setActionExpression

public void setActionExpression(MethodExpression actionExpression)

Description copied from interface: ActionSource2

Set the MethodExpression pointing at the appication action to be invoked, if this UIComponent is activated by the user, during the Apply Request Values or Invoke Application phase of the request processing lifecycle, depending on the value of the immediate property.

Any method referenced by such an expression must be public, with a return type of String, and accept no parameters.

规范说明:

setActionExpression in interface ActionSource2

参数:

actionExpression - The new method expression

addActionListener

public void addActionListener(ActionListener listener)

Description copied from interface: ActionSource

Add a new ActionListener to the set of listeners interested in being notified when ActionEvents occur.

规范说明:

addActionListener in interface ActionSource

参数:

listener - The ActionListener to be added

抛出异常:

NullPointerException - if listener is null

getActionListeners

public ActionListener[] getActionListeners()

Description copied from interface: ActionSource

Return the set of registered ActionListeners for this ActionSource instance. If there are no registered listeners, a zero-length array is returned.

规范说明:

getActionListeners in interface ActionSource

removeActionListener

public void removeActionListener(ActionListener listener)

Description copied from interface: ActionSource

Remove an existing ActionListener (if any) from the set of listeners interested in being notified when ActionEvents occur.

规范说明:

removeActionListener in interface ActionSource

参数:

listener - The ActionListener to be removed

抛出异常:

NullPointerException - if listener is null

saveState

public Object saveState(FacesContext context)

Description copied from interface: StateHolder

Gets the state of the instance as a Serializable Object.

If the class that implements this interface has references to instances that implement StateHolder (such as a UIComponent with event handlers, validators, etc.) this method must call the StateHolder.saveState(javax.faces.context.FacesContext) method on all those instances as well. This method must not save the state of children and facets. That is done via the StateManager

This method must not alter the state of the implementing object. In other words, after executing this code:

 Object state = component.saveState(facesContext);
 

component should be the same as before executing it.

The return from this method must be Serializable

规范说明:

saveState in interface StateHolder

重写:

saveState in class UIComponentBase

public void restoreState(FacesContext context,
                         Object state)

public void broadcast(FacesEvent event)
               throws AbortProcessingException

public void queueEvent(FacesEvent e)