Overriding Core Classes with Ext Plugins

A supported use case for using Ext plugins in Liferay DXP is overriding its core classes (e.g., portal-impl, portal-kernel, etc.). You can reference the Finding Core Liferay Portal Artifacts section for help distinguishing core classes. Make sure you’ve reviewed the generalized Customization with Ext Plugins section before creating an Ext plugin.

As an example, you’ll create a sample Ext plugin that overwrites the PortalImpl core class residing in the portal-impl.jar. You’ll edit the PortalImpl.getComputerName() method, which returns your server’s node name. The Ext plugin will override the entire PortalImpl class, adding the method modifying the server’s returned node name.

1. Navigate to your Liferay Workspace’s root folder and run the following command:

   blade create -t war-core-ext portal-impl-override
   

   Your Ext plugin is generated and now resides in the workspace’s /ext folder with the name you assigned.

2. Displaying the server node name in your Liferay DXP installation is set to false by default. You’ll need to enable this property. To do this, navigate into your Liferay bundle’s root folder and create a portal-ext.properties file. In that file, insert the following property:

   web.server.display.node=true
   

   Now your server’s node name will be displayed once your Liferay bundle is restarted.

3. In the /extImpl/java folder, create the folder structure matching the class’s folder structure you’d like to override (e.g., com/liferay/portal/util). Then create the new Java class that will override the existing core class; your new class must have the same name as the original.

4. Copy all of the original class’s (e.g., PortalImpl) logic into your new class. Then modify the method you want to customize. For this example, you want to edit the getComputerName() method. Therefore, replace it with the method below:

   @Override
   public String getComputerName() {
       return "sample_portalimpl_ext_installed_successfully_" + _computerName;
   }
   

   The method defined in the new class overrides the PortalImpl.getComputerName() method. The sample_portalimpl_ext_installed_successfully_ String is now prefixed to your server’s node name.

When your Ext plugin is deployed, your new Java class will override the core PortalImpl class.

Awesome! You’ve created an Ext plugin that overrides a core class in Liferay DXP! Follow the instructions in the Deploy the Plugin article to deploy it to your server.