usercontainer.java

A Java web application, based on Struts and Hibernate, that serves as an online running log. Users m

/* @LICENSE_COPYRIGHT@ */
package net.sf.irunninglog.servlet;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionBindingEvent;
import javax.servlet.http.HttpSessionBindingListener;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import net.sf.irunninglog.service.ICRUDService;
import net.sf.irunninglog.service.IQueryService;
import net.sf.irunninglog.service.ServiceFactory;

/**
 * Utility object used to wrap any resources that might otherwise be stored in
 * the user's session.  This class provides a single access point for these
 * resources, and eliminated the need for other application components to
 * interact directly with a user's session.  The container for the current user
 * may be obtained from a request by calling the
 * <code>getUserContainer(HttpServletRequest)</code> method.
 *
 * <p/>
 *
 * As this class is mainly used to wrap access to the user's session, The
 * internal methods for initialzing and cleaning up resources are tied to the
 * events that bind the container to the session.  This class implements the
 * <code>HttpSessionBindingListener</code> to listen for these events and
 * respond appropriately by initializing/cleaning up any resources.
 *
 * <p/>
 *
 * @author <a href="mailto:[e-mail]">Allan Lewis</a>
 * @version $Revision: 1.1.1.1 $ $Date: 2005/06/23 01:48:59 $
 * @since iRunningLog 1.0
 * @see #getUserContainer(HttpServletRequest)
 * @see #valueBound(HttpSessionBindingEvent)
 * @see #valueUnbound(HttpSessionBindingEvent)
 */
public final class UserContainer implements HttpSessionBindingListener {

    /** <code>Log</code> instance for this class. */
    private static final Log LOG = LogFactory.getLog(UserContainer.class);

    /** The service implementation used to handle CRUD requests. */
    private ICRUDService mCRUDService;
    /** The service implementation used to handle query requests. */
    private IQueryService mQueryService;
    /** The current user's session. */
    private HttpSession mSession;
    /** The user name of the user whose session holds this container. */
    private String mUserName;

    /** Context under which the container is bound in the user's session. */
    private static final String SESSION_CONTEXT = "UserContainer";

    /**
     * Get the container for the current user based on the user's request.
     * This will obtain the current container from the session (creating and
     * binding it to the session if needed).
     *
     * @param request The request (containing the user's session) being
     *                processed
     * @return The container bound to the current user's session
     */
    public static UserContainer getUserContainer(HttpServletRequest request) {
        HttpSession session = request.getSession(false);

        if (session == null) {
            LOG.error("The request does not contain a valid session");
            throw new IllegalArgumentException("The request does not contain a"
                                               + " valid session");
        }

        UserContainer container =
            (UserContainer) session.getAttribute(SESSION_CONTEXT);

        if (container == null) {
            container = new UserContainer(request);

            if (LOG.isDebugEnabled()) {
                LOG.debug("getUserContainer: Created a new container for '"
                          + container.getUserName() + "'");
            }

            session.setAttribute(SESSION_CONTEXT, container);
        }

        return container;
    }

    /**
     * Create a new container object, using a given request.
     *
     * @param request The request containing the current user's user name
     */
    private UserContainer(HttpServletRequest request) {
        super();

        if (request == null || request.getUserPrincipal() == null
            || request.getUserPrincipal().getName() == null) {

            LOG.error("Cannot create a UserContainer without a valid principal"
                      + " name");
            throw new NullPointerException("Cannot create a UserContainer "
                                           + "without a valid principal name");
        }

        mUserName = request.getUserPrincipal().getName();
        mSession = request.getSession(false);
    }

    /**
     * Get the service object used to handle any CRUD (create, read, update,
     * delete) actions.
     *
     * @return The service implementation used to perform CRUD actions
     */
    public ICRUDService getCRUDService() {
        return mCRUDService;
    }

    /**
     * Get the service object used to handle any query actions.
     *
     * @return The service implementation used to perform query actions
     */
    public IQueryService getQueryService() {
        return mQueryService;
    }

    /**
     * Get the current user's user name.  This will return the user name of the
     * user who created this container (and in whose session this container
     * is bound).
     *
     * @return The current user name
     */
    public String getUserName() {
        return mUserName;
    }

    /**
     * Log the current user out of the application.  This will invalidate the
     * user's session and make it impossible for the user to interact with the
     * applicaiton without logging in again.
     */
    public void logout() {
        if (LOG.isDebugEnabled()) {
            LOG.debug("logout: Logging '" + getUserName()
                      + "' out of the application");
        }

        mSession.invalidate();
    }

    /**
     * Perform any needed work when the container is bound to a session.
     * Any resources needed by the container should be created/initialized
     * here.
     *
     * @param event The event indicating that the container was
     *              bound to a session
     */
    public void valueBound(HttpSessionBindingEvent event) {
        if (LOG.isDebugEnabled()) {
            LOG.debug("valueBound: Container for '" + mUserName
                      + "' bound into session");
        }

        init();
    }

    /**
     * Create and initialize any resources used by this container.
     */
    private void init() {
        if (LOG.isDebugEnabled()) {
            LOG.debug("init: Initializing container for '" + mUserName
                      + "'");
        }

        String serviceName = ICRUDService.SERVICE_NAME;
        mCRUDService =
            (ICRUDService) ServiceFactory.newService(serviceName);

        if (LOG.isDebugEnabled()) {
            LOG.debug("init: Created CRUD Service " + mCRUDService);
        }

        serviceName = IQueryService.SERVICE_NAME;
        mQueryService =
            (IQueryService) ServiceFactory.newService(serviceName);

        if (LOG.isDebugEnabled()) {
            LOG.debug("init: Created Query Service " + mQueryService);
        }
    }

    /**
     * Perform any needed work when the container is unbound from a session.
     * This should handle the work of cleaning up any resources used by the
     * container.
     *
     * @param event The event indicating that the container was
     *              unbound from a session
     */
    public void valueUnbound(HttpSessionBindingEvent event) {
        if (LOG.isDebugEnabled()) {
            LOG.debug("valueUnbound: Container for '" + mUserName
                      + "' unbound from session");
        }

        cleanup();
    }

    /**
     * Cleanup any resources used by this container.
     */
    private void cleanup() {
        if (LOG.isDebugEnabled()) {
            LOG.debug("cleanup: Cleaning up container for '" + mUserName + "'");
        }

        mCRUDService = null;
        mQueryService = null;
    }

    /**
     * Custom toString override to provide a meaningful <code>String</code>
     * representation of this object.
     *
     * @return A <code>String</code> representation of this object
     */
    public String toString() {
        StringBuffer buff = new StringBuffer();

        buff.append(getClass());
        buff.append("[userName='");
        buff.append(getUserName());
        buff.append("' CRUDService=");
        buff.append(mCRUDService);
        buff.append(" QueryService=");
        buff.append(mQueryService);
        buff.append(" session=");
        buff.append(mSession);
        buff.append("]");

        return buff.toString();
    }

}