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.web;
018
019
020 import java.io.IOException;
021 import java.util.EmptyStackException;
022 import javax.servlet.RequestDispatcher;
023 import javax.servlet.ServletException;
024 import javax.servlet.ServletRequest;
025 import javax.servlet.ServletResponse;
026 import org.apache.commons.workflow.Context;
027 import org.apache.commons.workflow.Step;
028 import org.apache.commons.workflow.StepException;
029 import org.apache.commons.workflow.base.BaseStep;
030
031
032 /**
033 * <p>Unconditionally transfer control to the step that is identified by
034 * a request parameter with the specified name.</p>
035 *
036 * <p>Supported Attributes:</p>
037 * <ul>
038 * <li><strong>step</strong> - Name of a request parameter, included on the
039 * current request, that contains the identifier of the Step (within the
040 * current Activity) to which control should be transferred. If not
041 * specified, a request parameter named <code>step</code> is used.</li>
042 * </ul>
043 *
044 * @version $Revision: 155475 $ $Date: 2005-02-26 13:31:11 +0000 (Sat, 26 Feb 2005) $
045 * @author Craig R. McClanahan
046 */
047
048 public class GotoStep extends BaseStep {
049
050
051 // ----------------------------------------------------------= Constructors
052
053
054 /**
055 * Construct a default instance of this Step.
056 */
057 public GotoStep() {
058
059 super();
060
061 }
062
063
064 /**
065 * Construct an instance of this Step with the specified identifier.
066 *
067 * @param id Step identifier
068 */
069 public GotoStep(String id) {
070
071 super();
072 setId(id);
073
074 }
075
076
077 /**
078 * Construct a fully configured instance of this Step.
079 *
080 * @param id Step identifier
081 * @param step Request parameter name containing our step identifier
082 */
083 public GotoStep(String id, String step) {
084
085 super();
086 setId(id);
087 setStep(step);
088
089 }
090
091
092 // ------------------------------------------------------------- Properties
093
094
095 /**
096 * The request parameter containing the identifier of the Step to which
097 * control should be transferred.
098 */
099 protected String step = "step";
100
101 public String getStep() {
102 return (this.step);
103 }
104
105 public void setStep(String step) {
106 this.step = step;
107 }
108
109
110 // --------------------------------------------------------- Public Methods
111
112
113 /**
114 * Perform the executable actions related to this Step, in the context of
115 * the specified Context.
116 *
117 * @param context The Context that is tracking our execution state
118 *
119 * @exception StepException if a processing error has occurred
120 */
121 public void execute(Context context) throws StepException {
122
123 // Make sure our executing Context is a WebContext
124 if (!(context instanceof WebContext))
125 throw new StepException("Execution context is not a WebContext",
126 this);
127 WebContext webContext = (WebContext) context;
128
129 // Locate the step identifier to which we will transfer control
130 ServletRequest request = webContext.getServletRequest();
131 String id = request.getParameter(step);
132 if (id == null)
133 throw new StepException("No request parameter '" + step + "'",
134 this);
135
136
137 // Locate the step to which we will transfer control
138 Step next = getOwner().findStep(id);
139 if (next == null)
140 throw new StepException("Cannot find step '" + id + "'", this);
141
142 // Tell our Context to transfer control
143 context.setNextStep(next);
144
145 }
146
147
148 /**
149 * Render a string representation of this Step.
150 */
151 public String toString() {
152
153 StringBuffer sb = new StringBuffer("<web:goto");
154 if (getId() != null) {
155 sb.append(" id=\"");
156 sb.append(getId());
157 sb.append("\"");
158 }
159 sb.append(" step=\"");
160 sb.append(getStep());
161 sb.append("\"/>");
162 return (sb.toString());
163
164 }
165
166
167 }