Source Code Cross Referenced for RegexpRequestParameterSelector.java in  » Content-Management-System » apache-lenya-2.0 » org » apache » cocoon » selection » Java Source Code / Java DocumentationJava Source Code and Java Documentation

001:        /*
002:         * Licensed to the Apache Software Foundation (ASF) under one or more
003:         * contributor license agreements.  See the NOTICE file distributed with
004:         * this work for additional information regarding copyright ownership.
005:         * The ASF licenses this file to You under the Apache License, Version 2.0
006:         * (the "License"); you may not use this file except in compliance with
007:         * the License.  You may obtain a copy of the License at
008:         * 
009:         *      http://www.apache.org/licenses/LICENSE-2.0
010:         * 
011:         * Unless required by applicable law or agreed to in writing, software
012:         * distributed under the License is distributed on an "AS IS" BASIS,
013:         * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014:         * See the License for the specific language governing permissions and
015:         * limitations under the License.
016:         */
017:        package org.apache.cocoon.selection;
018:
019:        import java.util.Map;
020:
021:        import org.apache.avalon.framework.configuration.Configuration;
022:        import org.apache.avalon.framework.configuration.ConfigurationException;
023:        import org.apache.avalon.framework.parameters.Parameters;
024:        import org.apache.cocoon.environment.ObjectModelHelper;
025:
026:        /**
027:         * <p>The {@link RegexpRequestParameterSelector} class defines a selector matching
028:         * specific request parameters to configured regular-expression patterns.</p> 
029:         *
030:         * <p>The configuration of an {@link RegexpRequestParameterSelector} follows exactly
031:         * what has been outlined in {@link AbstractRegexpSelector} regarting regular
032:         * expression patterns, and additionally it requires an extra configuration element
033:         * specifying the request parameter whose value needs to be matched:</p>
034:         * 
035:         * <pre>
036:         * &lt;map:components&gt;
037:         *   ...
038:         *   &lt;map:selectors default="..."&gt;
039:         *     &lt;map:selector name="..." src="org.apache.cocoon.selection...."&gt;
040:         *       &lt;pattern name="empty"&gt;^$&lt;/pattern&gt;
041:         *       &lt;pattern name="number"&gt;^[0-9]+$&lt;/pattern&gt;
042:         *       &lt;pattern name="string"&gt;^.+$&lt;/pattern&gt;
043:         *       &lt;parameter-name&gt;...&lt;/parameter-name&gt;
044:         *     &lt;/map:selector&gt;
045:         *  &lt;/map:selectors&gt;
046:         * &lt;/map:components&gt;
047:         * </pre>
048:         * 
049:         * <p>If not configured, or if it needs to be overriddent, the parameter name can
050:         * also be specified as a <code>&lt;map:parameter&nbsp;.../&gt;</code> inside the
051:         * pipeline itself.</p>
052:         * 
053:         * @version CVS $Id: RegexpRequestParameterSelector.java 30941 2004-07-29 19:56:58Z vgritsenko $
054:         * @author <a href="mailto:pier@apache.org">Pier Fumagalli</a>
055:         */
056:        public class RegexpRequestParameterSelector extends
057:                AbstractRegexpSelector {
058:
059:            /** <p>The name of the parameter to work on.</p> */
060:            protected String parameterName;
061:
062:            /**
063:             * <p>Create a new {@link RegexpRequestParameterSelector} instance.</p>
064:             */
065:            public RegexpRequestParameterSelector() {
066:                super ();
067:            }
068:
069:            /**
070:             * <p>Configure this instance parsing all regular expression patterns and
071:             * storing the parameter name upon which selection occurs.</p>
072:             * 
073:             * @param configuration the {@link Configuration} instance where configured
074:             *                      patterns are defined.
075:             * @throws ConfigurationException if one of the regular-expression to configure
076:             *                                could not be compiled.
077:             */
078:            public void configure(Configuration configuration)
079:                    throws ConfigurationException {
080:                super .configure(configuration);
081:                this .parameterName = configuration.getChild("parameter-name")
082:                        .getValue(null);
083:            }
084:
085:            /**
086:             * <p>Return the value of the parameter identified by the configured parameter
087:             * name, if any.</p>
088:             * 
089:             * @param objectModel the Cocoon object model.
090:             * @param parameters the {@link Parameters} associated with the pipeline.
091:             * @return the value of the configured request parameter or <b>null</b>.
092:             */
093:            public Object getSelectorContext(Map objectModel,
094:                    Parameters parameters) {
095:                String name = parameters.getParameter("parameter-name",
096:                        this .parameterName);
097:                if (name == null) {
098:                    this .getLogger()
099:                            .warn("No parameter name given -- failing.");
100:                    return null;
101:                }
102:                return ObjectModelHelper.getRequest(objectModel).getParameter(
103:                        name);
104:            }
105:        }