Class Composition
- java.lang.Object
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- org.zkoss.zk.ui.util.Composition
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- All Implemented Interfaces:
Initiator
,InitiatorExt
public class Composition extends java.lang.Object implements Initiator, InitiatorExt
Composition manager that compose the given components into a whole page per the "insert" components and "define" components annotations. The "define" components will attach itself on to the "insert" component with the same annotated joinId. That is, the "insert" component is the parent component of the "define" components with the same annotated joinId. Note that "insert" components can NOT have duplicate joinId in a page while "define" components can because you can have multiple child components but you cannot have multiple parent components. Also note that a "define" components must be a root component of the page.
This Composition manager is useful when you need to do layout injection or you want to design a common page template across multiple pages.
- You first design a template with "insert" components telling where the insert points are. Each insert component has to be given a distinguish joinId in a page(e.g. <window self="@{insert(content)}"/> here the "content" is the joinId).
- Then in the real page, you have root "define" components telling which "define" components are to be attach onto the "insert" component with the same joinId (e.g. <label self="@{define(content)}"; here the "content" is the joinId).
- This Composition class is designed as a page
Initiator
and aInitiatorExt
, so you have to specify in the real page as following to use it.<?init class="org.zkoss.zk.ui.util.Composition" [arg0="TEMPLATE1"[, arg1="TEMPLATE2"]...]?> ...
Where the arg0 ~ argx you can give zul template uri. This implementation use Excecutions.createComponents() to create them and then do the real composition in theInitiatorExt.doAfterCompose(Page, Component[])
. - If more than one "define" components have the same joinId, they are attached onto the "insert" component in the sequence of the definition.
- If a "define" component cannot find the corresponding "insert" component, it will be simply detached from the page.
- Also you can prepare a parent component and pass it in via Execution.getCurrent().setAttribute(Composition.PARENT, parent) then this implementation will attach finally composed root components as the children of the provided parent.
- If you did not provide the parent component, the finally composed root components are attached directly to the current page.
- Since:
- 3.5.2
- Author:
- henrichen
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Field Summary
Fields Modifier and Type Field Description static java.lang.String
PARENT
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Constructor Summary
Constructors Constructor Description Composition()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
doAfterCompose(Page page, Component[] comps)
Called after all components are created (a.k.a., composed), and before any event is processed.boolean
doCatch(java.lang.Throwable ex)
Called when an exception occurs during the evaluation of the page.void
doFinally()
Do the cleanup after the page has been evaluated.void
doInit(Page page, java.util.Map<java.lang.String,java.lang.Object> args)
Does the initializes before the page is evaluated.
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Field Detail
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PARENT
public static final java.lang.String PARENT
- See Also:
- Constant Field Values
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Method Detail
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doCatch
public boolean doCatch(java.lang.Throwable ex) throws java.lang.Exception
Description copied from interface:InitiatorExt
Called when an exception occurs during the evaluation of the page.If you don't want to handle the exception, simply returns false.
boolean doCatch(Throwable ex) {return false;}
An exception thrown in this method is simply logged. It has no effect on the execution. If you want to ignore the exception, just return true.
Notice: this method won't be called if the exception occurs in
Initiator.doInit(org.zkoss.zk.ui.Page, java.util.Map<java.lang.String, java.lang.Object>)
.- Specified by:
doCatch
in interfaceInitiatorExt
- Parameters:
ex
- the exception being thrown- Returns:
- whether to ignore the exception. If false is returned, the exception will be re-thrown. Note: once an initiator's doCatch returns true, the exception will be ignored and it means doCatch of the following initiators won't be called. Prior to ZK 3.0.0, void is returned and it means always re-thrown
- Throws:
java.lang.Exception
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doFinally
public void doFinally() throws java.lang.Exception
Description copied from interface:InitiatorExt
Do the cleanup after the page has been evaluated. It won't be called ifInitiator.doInit(org.zkoss.zk.ui.Page, java.util.Map<java.lang.String, java.lang.Object>)
throws an exception. However,it is always called no matter whetherInitiatorExt.doCatch(java.lang.Throwable)
is called.An exception thrown in this method is simply logged. It has no effect on the execution.
- Specified by:
doFinally
in interfaceInitiatorExt
- Throws:
java.lang.Exception
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doInit
public void doInit(Page page, java.util.Map<java.lang.String,java.lang.Object> args) throws java.lang.Exception
Description copied from interface:Initiator
Does the initializes before the page is evaluated.Note: when it is called,
Page.getDesktop()
,Page.getId()
andPage.getTitle()
all return null, since the page is not initialized yet. To get the current desktop, you have to useExecution.getDesktop()
(fromExecutions.getCurrent()
) instead. On the other hand, you can set the page's ID, title or style in this method (to override the declarations in the page definition) byPage.setId(java.lang.String)
,Page.setTitle(java.lang.String)
andPage.setStyle(java.lang.String)
. In additions,Page.getRequestPath()
andPage.getAttribute(java.lang.String, int)
are all available.- Specified by:
doInit
in interfaceInitiator
- Parameters:
page
- the page being evaluatedargs
- a map of arguments. Prior to 3.6.2, it is an array. To upgrade, use args.get("arg0") instead of args[0], args.get("arg1") instead of args[1] and so on. Of course, it is better to have a more meaningful name for each argument. If no argument is specified, args is an empty map (never null).- Throws:
java.lang.Exception
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doAfterCompose
public void doAfterCompose(Page page, Component[] comps) throws java.lang.Exception
Description copied from interface:InitiatorExt
Called after all components are created (a.k.a., composed), and before any event is processed.It won't be called if an un-caught exception occurs when creating components.
- Specified by:
doAfterCompose
in interfaceInitiatorExt
- Parameters:
page
- the page that new components are attached to. It is the same asInitiator.doInit(org.zkoss.zk.ui.Page, java.util.Map<java.lang.String, java.lang.Object>)
's page argument.comps
- the root components being created (never null, but the length might be zero). Note: It is not necessary the same asPage.getRoots()
, since this method might be called thruExecutions.createComponents(java.lang.String, org.zkoss.zk.ui.Component, java.util.Map<?, ?>)
.- Throws:
java.lang.Exception
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