It are in essence taghandlers. I.e. classes extending from TagHandler.
Here's a Hello World taghandler.
com.example.HelloTagHandler
public class HelloTagHandler extends TagHandler {
public HelloTagHandler(TagConfig config) {
super(config);
}
@Override
public void apply(FaceletContext context, UIComponent parent) throws IOException {
// Do your job here. This example dynamically adds another component to the parent.
if (ComponentHandler.isNew(parent)) {
UIOutput child = new HtmlOutputText();
child.setValue("Hello World");
parent.getChildren().add(child);
}
nextHandler.apply(context, parent); // Delegate job further to first next tag in tree hierarchy.
}
}
/WEB-INF/my.taglib.xml
<?xml version="1.0" encoding="UTF-8"?>
<facelet-taglib
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-facelettaglibrary_2_0.xsd"
version="2.0"
>
<namespace>http://example.com/my</namespace>
<tag>
<tag-name>hello</tag-name>
<handler-class>com.example.HelloTagHandler</handler-class>
</tag>
</facelet-taglib>
/WEB-INF/web.xml (note: this part is not mandatory when my.taglib.xml is in /META-INF folder of a JAR file inside /WEB-INF/lib like as with JSF component libraries):
<context-param>
<param-name>javax.faces.FACELETS_LIBRARIES</param-name>
<param-value>/WEB-INF/my.taglib.xml</param-value>
</context-param>
Usage in /some.xhtml
<html ... xmlns:my="http://example.com/my">
...
<my:hello />
To see the source code of Mojarra implementation of <ui:composition> and <ui:include>, click the links.
See also:
与恶龙缠斗过久,自身亦成为恶龙；凝视深渊过久,深渊将回以凝视…
