001package org.apache.turbine.modules.screens;
002
003/*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements.  See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership.  The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License.  You may obtain a copy of the License at
011 *
012 *   http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied.  See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022
023import org.apache.turbine.pipeline.PipelineData;
024import org.apache.velocity.context.Context;
025
026/**
027 * VelocitySecureScreen
028 *
029 * Always performs a Security Check that you've defined before
030 * executing the doBuildTemplate().  You should extend this class and
031 * add the specific security check needed.  If you have a number of
032 * screens that need to perform the same check, you could make a base
033 * screen by extending this class and implementing the isAuthorized().
034 * Then each screen that needs to perform the same check could extend
035 * your base screen.
036 *
037 * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
038 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a>
039 * @version $Id$
040 */
041public abstract class VelocitySecureScreen
042        extends VelocityScreen
043{
044    /**
045     * Implement this to add information to the context.
046     *
047     * @param pipelineData Turbine information.
048     * @param context Context for web pages.
049     * @throws Exception a generic exception.
050     */
051    @Override
052    protected abstract void doBuildTemplate(PipelineData pipelineData,
053                                            Context context)
054            throws Exception;
055
056    /**
057     * This method overrides the method in VelocityScreen to
058     * perform a security check first.
059     *
060     * @param pipelineData Turbine information.
061     * @throws Exception a generic exception.
062     */
063    @Override
064    protected void doBuildTemplate(PipelineData pipelineData)
065        throws Exception
066    {
067        if (isAuthorized(pipelineData))
068        {
069            doBuildTemplate(pipelineData, velocity.getContext(pipelineData));
070        }
071    }
072
073    /**
074     * Implement this method to perform the security check needed.
075     * You should set the template in this method that you want the
076     * user to be sent to if they're unauthorized.  See the
077     * VelocitySecurityCheck utility.
078     *
079     * @param pipelineData Turbine information.
080     * @return True if the user is authorized to access the screen.
081     * @throws Exception a generic exception.
082     */
083    protected abstract boolean isAuthorized(PipelineData pipelineData)
084            throws Exception;
085}