com.arsdigita.toolbox.ui
Class NullComponent

java.lang.Object
  com.arsdigita.toolbox.ui.NullComponent

All Implemented Interfaces:

Component, Lockable

public final class NullComponent

extends Object

implements Component

Version:

$Id: //core-platform/dev/src/com/arsdigita/toolbox/ui/NullComponent.java#5 $

Author:

Justin Ross <jross@redhat.com>

Field Summary

static String

versionId

Fields inherited from interface com.arsdigita.bebop.Component

BEBOP_XML_NS, CLASS, ID, ON_CLICK, STYLE

Constructor Summary

NullComponent()

Method Summary

Iterator	children() Returns an iterator over the children of this component.
void	generateXML(PageState state, Element parent) Adds a DOM subtree representing this component under the given parent node.
String	getClassAttr() Gets the class attribute.
String	getIdAttr() Gets the id attribute.
String	getKey() Retrieves the programmer-supplied key.
String	getStyleAttr() Gets the style attribute.
boolean	isLocked() Return whether an object is locked and thus immutable, or can still be modified.
boolean	isVisible(PageState state) Determines whether the component is visible in the request represented by state.
void	lock() Lock an object.
void	register(Form form, FormModel model) Registers form parameters with the form model for this form.
void	register(Page page) Registers state parameters for the page with its model.
void	respond(PageState state) Responds to the request.
void	setClassAttr(String clacc) Sets the class attribute.
void	setIdAttr(String id) Sets the id attribute.
Component	setKey(String key) Supplies a key for making parameter names unique.
void	setStyleAttr(String style) Sets the style attribute.
void	setVisible(PageState state, boolean visible) Changes the visibility of the component.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

versionId

public static final String versionId

See Also:

Constant Field Values

Constructor Detail

NullComponent

public NullComponent()

Method Detail

generateXML

public void generateXML(PageState state,
                        Element parent)

Description copied from interface: Component

Adds a DOM subtree representing this component under the given parent node. Uses the request values stored in state.

Specified by:

generateXML in interface Component

Parameters:

state - represents the current request

parent - the node under which the DOM subtree should be added

respond

public void respond(PageState state)
             throws javax.servlet.ServletException

Description copied from interface: Component

Responds to the request. This method is only called if the request was made from a link or form that the component put on the page in the PageState.stateAsURL() previous request.

No output should be generated on the HTTP response. The component can store intermediate results in the state by calling setAttribute.

This method is called before any output is printed to the HTTP response so that the component can forward to a different page and thereby commit the response.

Specified by:

respond in interface Component

Parameters:

state - represents the current request

Throws:

javax.servlet.ServletException

children

public Iterator children()

Description copied from interface: Component

Returns an iterator over the children of this component. If the component has no children, returns an empty (not null) iterator.

Specified by:

children in interface Component

Returns:

an iterator over the children of this component.

register

public void register(Page page)

Description copied from interface: Component

Registers state parameters for the page with its model. A simple component with a state parameter param would do the following in the body of this method:

   p.addComponent(this);
   p.addComponentStateParam(this, param);
 

You should override this method to set the default visibility of your component:

 public void register(Page p) {
     super.register(p);
     p.setVisibleDefault(childNotInitiallyShown,false);
     p.setVisibleDefault(anotherChild, false);
 }
 

Always call super.register when you override register. Otherwise your component may malfunction and produce errors like "Widget ... isn't associated with any Form"

Specified by:

register in interface Component

register

public void register(Form form,
                     FormModel model)

Description copied from interface: Component

Registers form parameters with the form model for this form. This method is only important for form sections and widgets (components that have a connection to an HTML form). Other components can implement it as a no-op.

Specified by:

register in interface Component

getClassAttr

public String getClassAttr()

Description copied from interface: Component

Gets the class attribute.

Specified by:

getClassAttr in interface Component

Returns:

the class attribute.

See Also:

Component.setClassAttr(String), Standard Attributes

setClassAttr

public void setClassAttr(String clacc)

Description copied from interface: Component

Sets the class attribute.

Specified by:

setClassAttr in interface Component

Parameters:

clacc - a valid XML name

See Also:

Standard Attributes, Component.getClassAttr()

getStyleAttr

public String getStyleAttr()

Description copied from interface: Component

Gets the style attribute.

Specified by:

getStyleAttr in interface Component

Returns:

the style attribute.

See Also:

Component.setStyleAttr(java.lang.String), Standard Attributes

setStyleAttr

public void setStyleAttr(String style)

Description copied from interface: Component

Sets the style attribute. style should be a valid CSS style, because its value will be copied verbatim to the output and appear as a style attribute in the top level XML or HTML output element.

Specified by:

setStyleAttr in interface Component

Parameters:

style - a valid CSS style description for use in the style attribute of an HTML tag

See Also:

Standard Attributes

getIdAttr

public String getIdAttr()

Description copied from interface: Component

Gets the id attribute.

Specified by:

getIdAttr in interface Component

Returns:

the id attribute.

See Also:

Standard Attributes, Component.setIdAttr(String id)

setIdAttr

public void setIdAttr(String id)

Description copied from interface: Component

Sets the id attribute. id should be an XML name that is unique within the Page in which this component is contained. The value of id is copied literally to the output and not used for internal processing.

Specified by:

setIdAttr in interface Component

Parameters:

id - a valid XML identifier

See Also:

Standard Attributes

setKey

public Component setKey(String key)

Description copied from interface: Component

Supplies a key for making parameter names unique. To be used instead of the component's index (see Component Prefix). To avoid collision with indexOf, it should (1) be a legal fragment of a cgi parameter, (2) differ from "g", and (3) not start with a digit.

Specified by:

setKey in interface Component

getKey

public String getKey()

Description copied from interface: Component

Retrieves the programmer-supplied key. Normally, there is no such key and the method returns null.

Specified by:

getKey in interface Component

Returns:

the programmer-supplied key.

isVisible

public boolean isVisible(PageState state)

Description copied from interface: Component

Determines whether the component is visible in the request represented by state.

Specified by:

isVisible in interface Component

Parameters:

state - represents the current request

Returns:

true if the component is visible in the request; false otherwise.

See Also:

setVisible, Description of Visibility above

setVisible

public void setVisible(PageState state,
                       boolean visible)

Description copied from interface: Component

Changes the visibility of the component. The component will keep the visibility that is set with this method in subsequent requests to this page.

Specified by:

setVisible in interface Component

Parameters:

state - represents the current request

visible - true if the component should be visible

See Also:

Description of Visibility above

lock

public void lock()

Description copied from interface: Lockable

Lock an object. Locked objects are to be considered immutable. Any attempt to modify them, e.g., through a setXXX method should lead to an exception.

Most lockable Bebop classes throw an IllegalStateException if an attempt is made to modify a locked instance.

Specified by:

lock in interface Lockable

isLocked

public boolean isLocked()

Description copied from interface: Lockable

Return whether an object is locked and thus immutable, or can still be modified.

Specified by:

isLocked in interface Lockable