Use Compiled Java Codes"
m ((via JWB)) |
m (replace tt with code (via JWB)) |
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== Event Handler Is zscript == | == Event Handler Is zscript == | ||
− | In addition to the < | + | In addition to the <code>zscript</code> element, [[ZK Component Reference/Common Operations/Event Handling/Event Listening#Declare_an_Event_Handler_in_a_ZUL_page | the event handler declared in a ZUL page]] is also interpreted at the runtime. For example, |
<syntaxhighlight line lang="xml"> | <syntaxhighlight line lang="xml"> | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
− | where < | + | where <code>doSomething()</code> is interpreted as <code>zscript</code>. Thus, for better performance, they should be replaced too. |
==Turn off the use of zscript== | ==Turn off the use of zscript== | ||
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= Use the deferred Attribute = | = Use the deferred Attribute = | ||
− | If you still need to write zscript codes, you can specify the < | + | If you still need to write zscript codes, you can specify the <code>deferred</code> attribute to defer the evaluation of zscript codes as follows. |
<syntaxhighlight line lang="xml" > | <syntaxhighlight line lang="xml" > | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
− | By specifying the < | + | By specifying the <code>deferred</code> attribute, the zscript codes it contains will not be evaluated when ZK renders a page. It means that the interpreter won't be loaded when ZK renders a page. This saves memory and speeds up page rendering. |
In the following example, the interpreter is loaded only when the button is clicked: | In the following example, the interpreter is loaded only when the button is clicked: | ||
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== The deferred Attribute and the onCreate Event == | == The deferred Attribute and the onCreate Event == | ||
− | It is worth to notice that, if the < | + | It is worth to notice that, if the <code>onCreate</code> event listener is written in zscript, the deferred option mentioned in the previous section becomes ''useless''. It is because the <code>onCreate</code> event is sent when the page is loaded. In other words, all deferred zscript will be evaluated when the page is loaded if the <code>onCreate</code> event listener is written in zscript as shown below. |
<syntaxhighlight line lang="xml" > | <syntaxhighlight line lang="xml" > | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
− | Then, prepare < | + | Then, prepare <code>MyWindow.java</code> as shown below. |
<syntaxhighlight line lang="java" > | <syntaxhighlight line lang="java" > | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
− | If you prefer to do the initialization right after the component (and all its children) is created, you can implement the <javadoc type="interface">org.zkoss.zk.ui.ext.AfterCompose</javadoc> interface as shown below. Note: the < | + | If you prefer to do the initialization right after the component (and all its children) is created, you can implement the <javadoc type="interface">org.zkoss.zk.ui.ext.AfterCompose</javadoc> interface as shown below. Note: the <code>afterCompose</code> method of the <code>AfterCompose</code> interface is evaluated at the Component Creation phase, while the <code>onCreate</code> event is evaluated in the Event Processing Phase. |
<syntaxhighlight line lang="java" > | <syntaxhighlight line lang="java" > | ||
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= Use the forward Attribute = | = Use the forward Attribute = | ||
− | To simplify the event flow, ZK components usually send the events to the component itself, rather than the parent or other targets. For example, when an user clicks a button, the < | + | To simplify the event flow, ZK components usually send the events to the component itself, rather than the parent or other targets. For example, when an user clicks a button, the <code>onClick</code> event is sent to the button. However, developers may need to forward the event to the window component by the use of the <code>onClick</code> event listener as follows. |
<source lang="xml" > | <source lang="xml" > | ||
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</source> | </source> | ||
− | As suggested in the previous sections, the performance can be improved by ''not'' using zscript at all. Thus, you can rewrite the above code snippet either with < | + | As suggested in the previous sections, the performance can be improved by ''not'' using zscript at all. Thus, you can rewrite the above code snippet either with <code>EventListener</code> or by specifying the <code>forward</code> attribute as follows. |
<source lang="xml" > | <source lang="xml" > |
Revision as of 14:14, 12 January 2022
Not to Use zscript for Better Performance
It is convenient to use zscript in ZUML, but it comes with a price: slower performance. The degradation varies from one application from another. It is suggested to use zsript only for fast prototyping, POC, or small projects. For large website, it is suggested to use ZK MVC/ZK MVVM instead. For example, with ZK MVC
1 <window apply="foo.MyComposer">
2 //omitted
You can handle all events and components in foo.MyComposer
. By the use of auto-wiring, it is straightforward to handle events and components.
Event Handler Is zscript
In addition to the zscript
element, the event handler declared in a ZUL page is also interpreted at the runtime. For example,
1 <button label="OK" onClick="doSomething()"/>
where doSomething()
is interpreted as zscript
. Thus, for better performance, they should be replaced too.
Turn off the use of zscript
Since 5.0.8
If you decide not to use zscript at all, you could turn on the disable-script configuration as follows, such that an exception will be thrown if zscript is used.
<system-config>
<disable-zscript>true</disable-zscript>
</system-config>
Use the deferred Attribute
If you still need to write zscript codes, you can specify the deferred
attribute to defer the evaluation of zscript codes as follows.
1 <zscript deferred="true">
2 </zscript>
By specifying the deferred
attribute, the zscript codes it contains will not be evaluated when ZK renders a page. It means that the interpreter won't be loaded when ZK renders a page. This saves memory and speeds up page rendering.
In the following example, the interpreter is loaded only when the button is clicked:
1 <window id="w">
2 <zscript deferred="true">
3 void addMore() {
4 new Label("More").setParent(w);
5 }
6 </zscript>
7 <button label="Add" onClick="addMore()"/>
8 </window>
The deferred Attribute and the onCreate Event
It is worth to notice that, if the onCreate
event listener is written in zscript, the deferred option mentioned in the previous section becomes useless. It is because the onCreate
event is sent when the page is loaded. In other words, all deferred zscript will be evaluated when the page is loaded if the onCreate
event listener is written in zscript as shown below.
1 <window onCreate="init()">
Rather, it is better to rewrite it as
1 <window use="my.MyWindow">
Then, prepare MyWindow.java
as shown below.
1 package my;
2 public class MyWindow extends Window {
3 public void onCreate() { //to process the onCreate event
4 ...
If you prefer to do the initialization right after the component (and all its children) is created, you can implement the AfterCompose interface as shown below. Note: the afterCompose
method of the AfterCompose
interface is evaluated at the Component Creation phase, while the onCreate
event is evaluated in the Event Processing Phase.
1 package my;
2 public class MyWindow extends Window implements org.zkoss.zk.ui.ext.AfterCompose {
3 public void afterCompose() { //to initialize the window
4 ...
Use the forward Attribute
To simplify the event flow, ZK components usually send the events to the component itself, rather than the parent or other targets. For example, when an user clicks a button, the onClick
event is sent to the button. However, developers may need to forward the event to the window component by the use of the onClick
event listener as follows.
<window id="w" onOK='alert("on OK")'>
<button label="OK" onClick='Events.postEvent("onOK", w, null)'/>
</window>
As suggested in the previous sections, the performance can be improved by not using zscript at all. Thus, you can rewrite the above code snippet either with EventListener
or by specifying the forward
attribute as follows.
<window apply="foo.MyComposer">
<button label="OK" forward="onOK"/>
</window>
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