com.github.wolfie.sessionguard.SessionGuard.java Source code

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Here is the source code for com.github.wolfie.sessionguard.SessionGuard.java

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// Copyright 2010 Henrik Paul
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.github.wolfie.sessionguard;

import java.util.Map;

import com.github.wolfie.sessionguard.client.ui.VSessionGuard;
import com.github.wolfie.sessionguard.exception.NonPositiveTimeSpanException;
import com.vaadin.Application;
import com.vaadin.service.ApplicationContext;
import com.vaadin.terminal.PaintException;
import com.vaadin.terminal.PaintTarget;
import com.vaadin.terminal.gwt.server.WebApplicationContext;
import com.vaadin.ui.AbstractComponent;

/**
 * Server side component for the VSessionGuard widget.
 */
@com.vaadin.ui.ClientWidget(com.github.wolfie.sessionguard.client.ui.VSessionGuard.class)
public class SessionGuard extends AbstractComponent {

    private static final long serialVersionUID = -8232615940183467323L;

    private int sessionTimeout = -2;
    private int timeoutWarningPeriodMinutes = 0;
    private String timeoutWarningXHTML = "It seems like you have been inactive for a while.<br/>"
            + "Please note that your session will end in _ minutes, unless you do something.";
    private boolean keepalive = false;

    @Override
    public void paintContent(final PaintTarget target) throws PaintException {
        target.addAttribute(VSessionGuard.A_TIMEOUT_SECS_INT, sessionTimeout);
        target.addAttribute(VSessionGuard.A_WARNING_PERIOD_MINS_INT, timeoutWarningPeriodMinutes);
        target.addAttribute(VSessionGuard.A_TIMEOUT_MSG_XHTML_STRING, timeoutWarningXHTML);
        target.addAttribute(VSessionGuard.A_KEEPALIVE_BOOL, keepalive);
        target.addVariable(this, VSessionGuard.V_PING_BOOL, false);
    }

    /**
     * {@inheritDoc}
     * 
     * @throws ClassCastException
     *           if <code>getApplication().getContext()</code> doesn't return an
     *           object instance of {@link WebApplicationContext}.
     */
    @Override
    public void attach() {
        super.attach();

        final Application application = getApplication();
        if (application != null) {

            final ApplicationContext context = application.getContext();
            if (context instanceof WebApplicationContext) {
                final WebApplicationContext webContext = (WebApplicationContext) context;
                sessionTimeout = webContext.getHttpSession().getMaxInactiveInterval();
            } else {
                throw new ClassCastException(
                        getClass() + " must be used in a " + WebApplicationContext.class.getName()
                                + ", currently trying to be used in a " + context.getClass().getName() + ".");
            }
        }
    }

    public boolean isKeptAlive() {
        return keepalive;
    }

    /**
     * <p>
     * Should the session be artificially kept alive by the {@link SessionGuard}.
     * If keep alive is enabled, no warning message will be presented.
     * </p>
     * <p>
     * By default, the session is not being kept alive.
     * </p>
     * <p>
     * <em>Note:</em> If you need to set this permanently for your application,
     * consider setting the <tt>session-timeout</tt> setting in your
     * <tt>web.xml</tt> instead.
     * 
     * @param keepAlive
     *          <tt>true</tt> if you want the {@link SessionGuard} to prevent the
     *          session to time out. <tt>false</tt> if you want to disable this
     *          feature.
     */
    public void setKeepalive(final boolean keepAlive) {
        keepalive = keepAlive;
        requestRepaint();
    }

    /**
     * <p>
     * The amount of time left in the session lifetime, until the warning message
     * will be presented.
     * </p>
     * <p>
     * If {@link #isKeptAlive()} returns <tt>true</tt>, or given warning period is
     * longer than the context's current session lifetime, no message will be
     * presented.
     * </p>
     * 
     * @param minutes
     *          The amount of time in minutes.
     * @throws NonPositiveTimeSpanException
     *           if <tt>minutes</tt> is zero or less.
     */
    public void setTimeoutWarningPeriod(final int minutes) {
        if (minutes > 0) {
            timeoutWarningPeriodMinutes = minutes;
            requestRepaint();
        } else {
            throw new NonPositiveTimeSpanException("'minutes' must be greater than zero");
        }
    }

    /**
     * @return The amount of minutes before session timeout that the warning is
     *         displayed.
     */
    public int getTimeoutWarningPeriod() {
        return timeoutWarningPeriodMinutes;
    }

    /**
     * <p>
     * Set a custom session timeout warning message
     * </p>
     * <p>
     * If {@link #isKeptAlive()} returns <tt>true</tt>, no message will be
     * presented.
     * </p>
     * 
     * @param timeoutWarningXHTML
     *          The warning message in XHTML-format. Use the underscore character
     *          '_' as a placeholder for remaining minutes in the session.
     * @throws NullPointerException
     *           if <tt>timeoutWarningHTML</tt> is <tt>null</tt>
     */
    public void setTimeoutWarningXHTML(final String timeoutWarningXHTML) {
        if (timeoutWarningXHTML != null) {
            this.timeoutWarningXHTML = timeoutWarningXHTML;
            requestRepaint();
        } else {
            throw new NullPointerException("timeoutWarningXHTML was null");
        }
    }

    /**
     * Get the currently used warning message
     * 
     * @return The current warning message in XHTML-format.
     */
    public String getTimeoutWarningXHTML() {
        return timeoutWarningXHTML;
    }

    @Override
    public void changeVariables(final Object source, final Map<String, Object> variables) {
        /*
         * Always ping back when something happens on the client side, to let
         * VSessionGuard know that something has happened, and so that it resets its
         * timer.
         */
        requestRepaint();
    }
}