001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry.util;
016    
017    import org.apache.hivemind.util.Defense;
018    
019    import java.util.Arrays;
020    import java.util.HashMap;
021    import java.util.Map;
022    import java.util.TreeMap;
023    
024    /**
025     * A wrapper around a Map that stores query parameter values. Map keys are
026     * strings. Map values can be simple strings or array of string (or null).
027     * 
028     * @author Howard M. Lewis Ship
029     * @since 4.0
030     */
031    public class QueryParameterMap
032    {
033        private final Map _parameters;
034    
035        public QueryParameterMap()
036        {
037            this(new HashMap());
038        }
039    
040        /**
041         * Constructor around an existing Map whose keys and values are expected to
042         * conform expected use (keys are strings, values are null, string or string
043         * array). The map passed in is retained ( not copied).
044         */
045    
046        public QueryParameterMap(Map parameterMap)
047        {
048            Defense.notNull(parameterMap, "parameterMap");
049    
050            _parameters = parameterMap;
051        }
052    
053        /**
054         * Replaces the parameter value for the given name wit the new value (which
055         * may be null).
056         */
057    
058        public void setParameterValue(String name, String value)
059        {
060            Defense.notNull(name, "name");
061    
062            _parameters.put(name, value);
063        }
064    
065        /**
066         * Replaces the parameter value for the given name wit the new list of
067         * values (which may be empty or null).
068         */
069    
070        public void setParameterValues(String name, String[] values)
071        {
072            Defense.notNull(name, "name");
073    
074            _parameters.put(name, values);
075        }
076    
077        /**
078         * Gets a query parameter value. If an array of values was stored, this
079         * returns the first value. May return null.
080         */
081    
082        public String getParameterValue(String name)
083        {
084            Defense.notNull(name, "name");
085    
086            Object values = _parameters.get(name);
087    
088            if (values == null || values instanceof String) return (String) values;
089    
090            String[] array = (String[]) values;
091    
092            return array[0];
093        }
094    
095        /**
096         * Returns the array of values for the specified parameter. If only a lone
097         * value was stored (via {@link #setParameterValue(String, String)}, then
098         * the value is wrapped as a string array and returned.
099         */
100        public String[] getParameterValues(String name)
101        {
102            Defense.notNull(name, "name");
103    
104            Object values = _parameters.get(name);
105    
106            if (values == null || values instanceof String[])
107                return (String[]) values;
108    
109            String loneValue = (String) values;
110    
111            return new String[] { loneValue };
112        }
113    
114        /**
115         * Returns the names of all parameters, sorted alphabetically.
116         */
117        public String[] getParameterNames()
118        {
119            int count = _parameters.size();
120    
121            String[] result = (String[]) _parameters.keySet().toArray(new String[count]);
122    
123            if (!TreeMap.class.isInstance(_parameters))
124                Arrays.sort(result);
125    
126            return result;
127        }
128    }