EDIT

package eu.etaxonomy.vaadin.mvp;

import java.io.Serializable;

import org.apache.log4j.Logger;

import org.springframework.beans.factory.annotation.Autowired;

import org.springframework.beans.factory.annotation.Qualifier;

import org.springframework.transaction.TransactionStatus;

import com.vaadin.spring.annotation.SpringComponent;

import com.vaadin.spring.annotation.ViewScope;

import eu.etaxonomy.cdm.api.application.CdmRepository;

import eu.etaxonomy.vaadin.ui.navigation.NavigationManager;

/**

 * AbstractPresenter is the base class of all presenter components. Presenter's

 * role is to govern the view and control the complex UI logic based on

 * notifications presenter receives from its view.

 *

 * @author Peter / Vaadin

 *

 * @param <V>

 *            type of the view this presenter governs

 */

@SpringComponent

@ViewScope

public abstract class AbstractPresenter<V extends ApplicationView> implements Serializable {

    private static final long serialVersionUID = 5260910510283481832L;

    public static final Logger logger = Logger.getLogger(AbstractPresenter.class);

	private V view;

	protected V getView() {

	    if(view == null){

            Logger.getLogger(this.getClass()).warn("CDM-VAADIN#6562: presenter " + toString() + " without view.");

        }

		return view;

	}

	@Autowired

	@Qualifier("cdmRepository")

	private CdmRepository repo;

	@Autowired

	private NavigationManager navigationManager;

	/**

	 * @return the repo

	 */

	public CdmRepository getRepo() {

	    return repo;

	}

	/**

	 * Notifies the presenter that its view is initialized so that presenter can

	 * start its own initialization if required.

	 *

	 * @param view

	 */

	protected final void init(V view) {

	    logger.trace("Presenter init");

		this.view = view;

		onPresenterReady();

	}

	/**

	 * Extending classes should overwrite this method in order to perform logic

	 * after presenter has finished initializing.

	 */

	protected void onPresenterReady() {

	    logger.trace("Presenter ready");

	}

	public final void onViewEnter() {

	    logger.trace("View entered");

	    TransactionStatus tx = getRepo().startTransaction();

	    handleViewEntered();

	    getRepo().commitTransaction(tx);

	}

	public final void onViewExit() {

	    handleViewExit();

	}

	/**

	 * Extending classes should overwrite this method to react to the event when

	 * user has navigated into the view that this presenter governs.

	 */

	public void handleViewEntered() {

	}

    /**

     * Extending classes may overwrite this method to react to

     * the event when user leaves the view that this presenter

     * governs.

     */

    public void handleViewExit() {

    }

    /**

     * @return the navigationManager

     */

    public NavigationManager getNavigationManager() {

        return navigationManager;

    }

}