4b7a0fae34
- Replace documentation on writing components with documentation on migrating away from components - Split documentation on extensions and extension points (extensions are always needed and EPs are quite uncommon) - Add documentation on listeners - Remove application and project components in sample plugins whenever possible
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| Plugin Extension Points |
By defining extension points in your plugin, you can allow other plugins to extend the functionality of your plugin. There are two types of extension points:
- Interface extension points allow other plugins to extend your plugins with code. When you define an interface extension point, you specify an interface, and other plugins will provide classes implementing that interface. You'll then be able to invoke methods on those interfaces.
- Bean extension points allow other plugins to extend your plugins with data. You specify the fully qualified name of an extension class, and other plugins will provide data which will be turned into instances of that class.
How to declare extension points
You can declare extensions and extension points in the plugin configuration file plugin.xml, within the <extensions> and <extensionPoints> sections, respectively.
To declare extension points in your plugin, add an <extensionPoints> section to your plugin.xml. Then insert a child element <extensionPoint> that defines the extension point name and the name of a bean class or an interface that is allowed to extend the plugin functionality in the name, beanClass and interface attributes, respectively.
To clarify this procedure, consider the following sample section of the plugin.xml file:
<extensionPoints>
<extensionPoint name="MyExtensionPoint1" beanClass="MyPlugin.MyBeanClass1">
<extensionPoint name="MyExtensionPoint2" interface="MyPlugin.MyInterface">
</extensionPoints>
- The
interfaceattribute sets an interface the plugin that contributes to the extension point must implement. - The
beanClassattribute sets a bean class that specifies one or several properties annotated with the@Attributeannotation.
The plugin that contributes to the extension point will read those properties from the plugin.xml file.
To clarify this, consider the following sample MyBeanClass1 bean class used in the above plugin.xml file:
public class MyBeanClass1 extends AbstractExtensionPointBean {
@Attribute("key")
public String key;
@Attribute("implementationClass")
public String implementationClass;
public String getKey() {
return key;
}
public String getClass() {
return implementationClass;
}
}
To declare an extension designed to access the MyExtensionPoint1 extension point, your plugin.xml file must contain the <MyExtensionPoint1> tag with the key and implementationClass attributes set to appropriate values (see sample below).