EDIT

package eu.etaxonomy.cdm.vaadin.util;

import java.sql.Connection;

import java.sql.DatabaseMetaData;

import java.sql.SQLException;

import javax.servlet.ServletContext;

import javax.sql.DataSource;

import org.springframework.context.ApplicationContext;

import org.springframework.web.context.support.WebApplicationContextUtils;

import com.vaadin.data.util.sqlcontainer.connection.J2EEConnectionPool;

import com.vaadin.data.util.sqlcontainer.connection.JDBCConnectionPool;

import com.vaadin.server.VaadinServlet;

import eu.etaxonomy.cdm.api.service.ITaxonNodeService;

/**

 * This helper was related to the problem that in the Vaadin framework it was

 * not possible to autowire beans from the underlying application context

 * as Vaadin preventes this possibility. To overcome this problem, this singleton

 * helper class has been written to retrieve the beans given the bean name.

 * <p>

 * Now that <code>vaadin-spring</code> is being used this class is in principle

 * no longer needed. It never the less been kept for some time to continue

 * provide the J2EEConnectionPool. Once a clear concept exist about to handle and

 * inject it in a proper way this class can be removed completely.

 *

 * @author c.mathew

 *

 * TODO This class may no longer needed in a couple of cases since <code>vaadin-spring</code>

 * is being used and spring beans can be injected now.

 *

 */

public class CdmSpringContextHelper {

    private final ApplicationContext context;

    private final DataSource dataSource;

    private final JDBCConnectionPool connPool;

    private static CdmSpringContextHelper contextHelper;

    private static DatabaseMetaData databaseMetaData;

    private CdmSpringContextHelper(ServletContext servletContext) throws SQLException {

        context = WebApplicationContextUtils.

                getRequiredWebApplicationContext(servletContext);

        dataSource = (DataSource)getBean("dataSource");

        connPool = new J2EEConnectionPool(dataSource);

    }

    public static CdmSpringContextHelper getCurrent() {

        if(VaadinServlet.getCurrent() == null || VaadinServlet.getCurrent().getServletContext() == null) {

            throw new RuntimeException("Vaadin Servlet or Vaadin Servlet Context not initialized");

        }

        if(contextHelper == null) {

            ServletContext sc = VaadinServlet.getCurrent().getServletContext();

            try {

                contextHelper = new CdmSpringContextHelper(sc);

            } catch (SQLException e) {

                // TODO Auto-generated catch block

                e.printStackTrace();

            }

        }

        return contextHelper;

    }

    private Object getBean(final String beanRef) {

        return context.getBean(beanRef);

    }

    private Object getBean(Class clazz) {

        return context.getBean(clazz);

    }

    public DataSource getDataSource() {

        return dataSource;

    }

    public JDBCConnectionPool getConnectionPool() {

        return connPool;

    }

//    public static JDBCConnectionPool createConnectionPool() {

//        return new J2EEConnectionPool(getCurrent().getDataSource());

//    }

//    public static JDBCConnectionPool getConnectionPool() {

//        return new J2EEConnectionPool(getCurrent().getDataSource());

//    }

    public static Connection getConnection() throws SQLException {

        return getCurrent().getDataSource().getConnection();

    }

    public static DatabaseMetaData getDatabaseMetaData() throws SQLException {

        if(databaseMetaData == null) {

            Connection conn = getConnection();

            databaseMetaData = conn.getMetaData();

            conn.close();

        }

        return databaseMetaData;

    }

    @Deprecated

    public static ITaxonNodeService getTaxonNodeService() {

        return (ITaxonNodeService)getCurrent().getBean(ITaxonNodeService.class);

    }

}