All the functionality provided by Liferay is enclosed in a layer of services that are accessed by the controller layer in portlets. This is a standard architecture, and it lets you change how a core portlet of Liferay behaves without changing the portlet itself; you’re customizing the backend services that the portlet uses. You can leverage this architecture to customize portal service behavior, and hook plugins are your tool for doing so.

Liferay generates dummy wrapper classes for all its services. For example, UserLocalServiceWrapper is created as a wrapper for UserLocalService, a service for adding, removing, and retrieving user accounts. To modify the functionality of UserLocalService from our hook, create a class that extends UserLocalServiceWrapper, override the methods you want to modify, and instruct Liferay to use your service class instead of the original.

  1. Inside example-hook/docroot/WEB-INF/src/com/liferay/sample/hook create a new file called with the following content:

    package com.liferay.sample.hook;
    import com.liferay.portal.kernel.exception.PortalException;
    import com.liferay.portal.kernel.exception.SystemException;
    import com.liferay.portal.model.User;
    import com.liferay.portal.service.UserLocalService;
    import com.liferay.portal.service.UserLocalServiceWrapper;
    public class MyUserLocalServiceImpl extends UserLocalServiceWrapper {
        public MyUserLocalServiceImpl(UserLocalService userLocalService) {
        public User getUserById(long userId)
            throws PortalException, SystemException {
                "## MyUserLocalServiceImpl.getUserById(" + userId + ")");
            return super.getUserById(userId);
  2. Edit liferay-hook.xml, located in the example-hook/docroot/WEB-INF directory, by adding the following after </custom-jsp-dir>:


Redeploy your hook and refresh your browser. In the terminal window running Liferay, you should see ## MyUserLocalServiceImpl.getUserById(…) messages displayed by your hook.

There are other Liferay services that you may need to extend to meet advanced requirements:

  • OrganizationLocalService: Adds, deletes and retrieves organizations. Also assigns users to organizations and retrieves the list of organizations of a given user.
  • GroupLocalService: Adds, deletes and retrieves sites.
  • LayoutLocalService: Adds, deletes, retrieves and manages pages of sites, organizations and users.

For a complete list of available services and their methods check the Liferay Portal 6.1 Javadocs or access the Javadocs for your version of Liferay at and selecting the javadocs link.

Now that you know how to override a portal service, let’s go a bit deeper and override a file.

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