001    /*
002     * Copyright 1999-2001,2004 The Apache Software Foundation.
003     * 
004     * Licensed under the Apache License, Version 2.0 (the "License");
005     * you may not use this file except in compliance with the License.
006     * You may obtain a copy of the License at
007     * 
008     *      http://www.apache.org/licenses/LICENSE-2.0
009     * 
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed under the License is distributed on an "AS IS" BASIS,
012     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013     * See the License for the specific language governing permissions and
014     * limitations under the License.
015     */ 
016    
017    package org.apache.commons.workflow.io;
018    
019    
020    import org.apache.commons.workflow.Context;
021    import org.apache.commons.workflow.Descriptor;
022    import org.apache.commons.workflow.StepException;
023    import org.apache.commons.workflow.base.DescriptorStep;
024    
025    
026    /**
027     * <p>For each associated <code>Descriptor</code>, print the value of the
028     * specified Java object to standard output.</p>
029     *
030     * <p><strong>WARNING</strong> - This will probably be
031     * replaced later by a more general purpose input/output mechanism.</p>
032     *
033     * @version $Revision: 155475 $ $Date: 2005-02-26 13:31:11 +0000 (Sat, 26 Feb 2005) $
034     * @author Craig R. McClanahan
035     */
036    
037    public class DisplayStep extends DescriptorStep {
038    
039    
040        // ----------------------------------------------------------= Constructors
041    
042    
043        /**
044         * Construct a default instance of this Step.
045         */
046        public DisplayStep() {
047    
048            super();
049    
050        }
051    
052    
053        /**
054         * Construct an instance of this Step with the specified identifier.
055         *
056         * @param id Step identifier
057         */
058        public DisplayStep(String id) {
059    
060            super();
061            setId(id);
062    
063        }
064    
065    
066        /**
067         * Construct an instance of this Step with the specified identifier
068         * and associated Descriptor.
069         *
070         * @param id Step identifier
071         * @param descriptor Initial descriptor
072         */
073        public DisplayStep(String id, Descriptor descriptor) {
074    
075            super();
076            setId(id);
077            addDescriptor(descriptor);
078    
079        }
080    
081    
082        // --------------------------------------------------------- Public Methods
083    
084    
085        /**
086         * Perform the executable actions related to this Step, in the context of
087         * the specified Context.
088         *
089         * @param context The Context that is tracking our execution state
090         *
091         * @exception StepException if a processing error has occurred
092         */
093        public void execute(Context context) throws StepException {
094    
095            // Process all associated descriptors
096            Descriptor descriptors[] = findDescriptors();
097            for (int i = 0; i < descriptors.length; i++) {
098                Object value = descriptors[i].get(context);
099                if (value == null)
100                    throw new StepException
101                        ("Cannot retrieve object for " + descriptors[i], this);
102                System.out.println(value);
103            }
104    
105        }
106    
107    
108    }