org.apache.wicket.ajax
Class AjaxRequestTarget

java.lang.Object
  extended by org.apache.wicket.ajax.AjaxRequestTarget
All Implemented Interfaces:
IRequestTarget, IPageRequestTarget

public class AjaxRequestTarget
extends java.lang.Object
implements IPageRequestTarget

A request target that produces ajax response envelopes used on the client side to update component markup as well as evaluate arbitrary javascript.

A component whose markup needs to be updated should be added to this target via AjaxRequestTarget#addComponent(Component) method. Its body will be rendered and added to the envelope when the target is processed, and refreshed on the client side when the ajax response is received.

It is important that the component whose markup needs to be updated contains an id attribute in the generated markup that is equal to the value retrieved from Component#getMarkupId(). This can be accomplished by either setting the id attribute in the html template, or using an attribute modifier that will add the attribute with value Component#getMarkupId() to the tag ( such as MarkupIdSetter )

Any javascript that needs to be evaluated on the client side can be added using AjaxRequestTarget#append/prependJavascript(String). For example, this feature can be useful when it is desirable to link component update with some javascript effects.

The target provides a listener interface AjaxRequestTarget.IListener that can be used to add code that responds to various target events by adding listeners via addListener(org.apache.wicket.ajax.AjaxRequestTarget.IListener)

Since:
1.2
Author:
Igor Vaynberg (ivaynberg), Eelco Hillenius

Nested Class Summary
static interface AjaxRequestTarget.IJavascriptResponse
          An ajax javascript response that allows users to add javascript to be executed on the client side
static interface AjaxRequestTarget.IListener
          An AjaxRequestTarget listener that can be used to respond to various target-related events
static interface AjaxRequestTarget.ITargetRespondListener
          Components can implement this interface to get a notification when AjaxRequestTarget begins to respond.
 
Constructor Summary
AjaxRequestTarget(Page page)
          Constructor
 
Method Summary
 void addChildren(MarkupContainer parent, java.lang.Class childCriteria)
          Visits all children of the specified parent container and adds them to the target if they are of same type as childCriteria
 void addComponent(Component component)
          Adds a component to the list of components to be rendered
 void addComponent(Component component, java.lang.String markupId)
          Adds a component to the list of components to be rendered
 void addJavascript(java.lang.String javascript)
          Deprecated. use appendJavascript(String javascript) instead
 void addListener(AjaxRequestTarget.IListener listener)
          Adds a listener to this target
 void appendJavascript(java.lang.String javascript)
          Adds javascript that will be evaluated on the client side after components are replaced
 void detach(RequestCycle requestCycle)
          This method is called at the end of a request cycle to indicate that processing is done and that cleaning up of the subject(s) of this target may be done.
protected  java.lang.String encode(java.lang.String str)
          Encodes a string so it is safe to use inside CDATA blocks
 boolean equals(java.lang.Object obj)
           
 void focusComponent(Component component)
          Sets the focus in the browser to the given component.
static AjaxRequestTarget get()
          Static method that returns current AjaxRequestTarget or null of no AjaxRequestTarget is available.
protected  java.lang.String getEncodingName()
           
 IHeaderResponse getHeaderResponse()
          Returns the header response associated with current AjaxRequestTarget.
 java.lang.String getLastFocusedElementId()
          Returns the HTML id of the last focused element.
 Page getPage()
          Gets the page instance.
 int hashCode()
           
protected  boolean needsEncoding(java.lang.String str)
           
 void prependJavascript(java.lang.String javascript)
          Adds javascript that will be evaluated on the client side before components are replaced
 void registerRespondListener(AjaxRequestTarget.ITargetRespondListener listener)
          Register the given respond listener.
 void respond(RequestCycle requestCycle)
          Generates a response.
 java.lang.String toString()
           
 
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
 

Constructor Detail

AjaxRequestTarget

public AjaxRequestTarget(Page page)
Constructor

Parameters:
page -
Method Detail

getPage

public Page getPage()
Description copied from interface: IPageRequestTarget
Gets the page instance.

Specified by:
getPage in interface IPageRequestTarget
Returns:
the page instance

addListener

public void addListener(AjaxRequestTarget.IListener listener)
Adds a listener to this target

Parameters:
listener -

addChildren

public final void addChildren(MarkupContainer parent,
                              java.lang.Class childCriteria)
Visits all children of the specified parent container and adds them to the target if they are of same type as childCriteria

Parameters:
parent -
childCriteria -

addComponent

public void addComponent(Component component)
Adds a component to the list of components to be rendered

Parameters:
component - component to be rendered

addComponent

public final void addComponent(Component component,
                               java.lang.String markupId)
Adds a component to the list of components to be rendered

Parameters:
markupId - id of client-side dom element that will be updated
component - component to be rendered

addJavascript

public final void addJavascript(java.lang.String javascript)
Deprecated. use appendJavascript(String javascript) instead

Adds javascript that will be evaluated on the client side after components are replaced

Parameters:
javascript -

focusComponent

public final void focusComponent(Component component)
Sets the focus in the browser to the given component. The markup id must be set. If the component is null the focus will not be set to any component.

Parameters:
component - The component to get the focus or null.

appendJavascript

public final void appendJavascript(java.lang.String javascript)
Adds javascript that will be evaluated on the client side after components are replaced

Parameters:
javascript -

detach

public void detach(RequestCycle requestCycle)
Description copied from interface: IRequestTarget
This method is called at the end of a request cycle to indicate that processing is done and that cleaning up of the subject(s) of this target may be done.

Specified by:
detach in interface IRequestTarget
Parameters:
requestCycle - the current request cycle
See Also:
IRequestTarget.detach(org.apache.wicket.RequestCycle)

equals

public boolean equals(java.lang.Object obj)
Overrides:
equals in class java.lang.Object
See Also:
Object.equals(java.lang.Object)

hashCode

public int hashCode()
Overrides:
hashCode in class java.lang.Object
See Also:
Object.hashCode()

prependJavascript

public final void prependJavascript(java.lang.String javascript)
Adds javascript that will be evaluated on the client side before components are replaced

Parameters:
javascript -

registerRespondListener

public void registerRespondListener(AjaxRequestTarget.ITargetRespondListener listener)
Register the given respond listener. The listener's AjaxRequestTarget.ITargetRespondListener.onTargetRespond(AjaxRequestTarget) method will be invoked when the AjaxRequestTarget starts to respond.

Parameters:
listener -

respond

public final void respond(RequestCycle requestCycle)
Description copied from interface: IRequestTarget
Generates a response.

Specified by:
respond in interface IRequestTarget
Parameters:
requestCycle - the current request cycle
See Also:
IRequestTarget.respond(org.apache.wicket.RequestCycle)

toString

public java.lang.String toString()
Overrides:
toString in class java.lang.Object
See Also:
Object.toString()

encode

protected java.lang.String encode(java.lang.String str)
Encodes a string so it is safe to use inside CDATA blocks

Parameters:
str -
Returns:
encoded string

getEncodingName

protected java.lang.String getEncodingName()
Returns:
name of encoding used to possibly encode the contents of the CDATA blocks

needsEncoding

protected boolean needsEncoding(java.lang.String str)
Parameters:
str -
Returns:
true if string needs to be encoded, false otherwise

getHeaderResponse

public IHeaderResponse getHeaderResponse()
Returns the header response associated with current AjaxRequestTarget. Beware that only renderOnDomReadyJavascript and renderOnLoadJavascript can be called outside the renderHeader(IHeaderResponse response) method. Calls to other render** methods will result in an exception being thrown.

Returns:
header response

get

public static AjaxRequestTarget get()
Static method that returns current AjaxRequestTarget or null of no AjaxRequestTarget is available.

Returns:
AjaxRequestTarget instance if current request is an Ajax request, null otherwise.

getLastFocusedElementId

public java.lang.String getLastFocusedElementId()
Returns the HTML id of the last focused element.

Returns:


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