001    // Copyright 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.hivemind.util;
016    
017    import org.apache.hivemind.ApplicationRuntimeException;
018    import org.apache.hivemind.HiveMind;
019    import org.apache.hivemind.Location;
020    import org.apache.hivemind.internal.Module;
021    
022    /**
023     * Code for creating an instance, possibly setting its {@link org.apache.hivemind.Location}, and
024     * possibly initializing its properties.
025     * 
026     * @author Howard M. Lewis Ship
027     * @since 1.1
028     */
029    public class InstanceCreationUtils
030    {
031        /**
032         * Creates an instance.
033         * 
034         * @param module
035         *            the referencing module, used to resolve partial class names
036         * @param initializer
037         *            The name of the class to instantiate, possibly followed by a list of properties
038         *            and values. I.e. <code>com.examples.MyBean,property=value</code>.
039         * @param location
040         *            The location to assign to the newly created instance, if it implements
041         *            {@link org.apache.hivemind.LocationHolder}. Also the location used to report
042         *            errors creating or configuring the instance.
043         */
044        public static Object createInstance(Module module, String initializer, Location location)
045        {
046            int commax = initializer.indexOf(',');
047    
048            String className = (commax < 0) ? initializer : initializer.substring(0, commax);
049    
050            Class objectClass = module.resolveType(className);
051    
052            try
053            {
054                Object result = objectClass.newInstance();
055    
056                HiveMind.setLocation(result, location);
057    
058                if (commax > 0)
059                    PropertyUtils.configureProperties(result, initializer.substring(commax + 1));
060    
061                return result;
062            }
063            catch (Exception ex)
064            {
065                // JDK 1.4 produces a good message here, but JDK 1.3 does not, so we
066                // create our own.
067    
068                throw new ApplicationRuntimeException(UtilMessages.unableToInstantiateInstanceOfClass(
069                        objectClass,
070                        ex), location, ex);
071            }
072    
073        }
074    }