intellij-sdk-code-samples/basics/plugin_structure/plugin_extension_points.md

title
Plugin Extension Points

Note

See Plugin Extensions for using extension points in your plugin.

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.

<extensionPoints>
  <extensionPoint name="myExtensionPoint1" beanClass="com.myplugin.MyBeanClass">
  <extensionPoint name="myExtensionPoint2" interface="com.myplugin.MyInterface">
</extensionPoints>

• The beanClass attribute sets a bean class that specifies one or several properties annotated with the @Attribute annotation.
• The interface attribute sets an interface the plugin that contributes to the extension point must implement.

The plugin that contributes to the extension point will read those properties from the plugin.xml file.

To clarify this, consider the following sample MyBeanClass bean class used in the above plugin.xml file:

public class MyBeanClass 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.

Tip

See Extension properties code insight on how to provide smart completion/validation.