1 /*
2 * Copyright 1999-2001,2004 The Apache Software Foundation.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package org.apache.commons.workflow.web;
18
19
20 import java.io.IOException;
21 import java.util.EmptyStackException;
22 import javax.servlet.RequestDispatcher;
23 import javax.servlet.ServletException;
24 import javax.servlet.ServletRequest;
25 import javax.servlet.ServletResponse;
26 import org.apache.commons.workflow.Context;
27 import org.apache.commons.workflow.StepException;
28 import org.apache.commons.workflow.base.BaseStep;
29 import org.apache.commons.workflow.util.WorkflowUtils;
30
31
32 /**
33 * <p>Perform a <code>RequestDispatcher.forward()</code> operation on the
34 * specified context relative path, and tell our <code>Context</code> to
35 * suspend execution until control is returned.</p>
36 *
37 * <p>Supported Attributes:</p>
38 * <ul>
39 * <li><strong>page</strong> - Context relative URL (starting with a slash)
40 * of the application resource to be forwarded to, or omitted to pop a
41 * computed String value from the top of the evaluation stack.</li>
42 * </ul>
43 *
44 * @version $Revision: 155475 $ $Date: 2005-02-26 13:31:11 +0000 (Sat, 26 Feb 2005) $
45 * @author Craig R. McClanahan
46 */
47
48 public class ForwardStep extends BaseStep {
49
50
51 // ----------------------------------------------------------= Constructors
52
53
54 /**
55 * Construct a default instance of this Step.
56 */
57 public ForwardStep() {
58
59 super();
60
61 }
62
63
64 /**
65 * Construct an instance of this Step with the specified identifier.
66 *
67 * @param id Step identifier
68 */
69 public ForwardStep(String id) {
70
71 super();
72 setId(id);
73
74 }
75
76
77 /**
78 * Construct a fully configured instance of this Step.
79 *
80 * @param id Step identifier
81 * @param page Context-relative url
82 */
83 public ForwardStep(String id, String page) {
84
85 super();
86 setId(id);
87 setPage(page);
88
89 }
90
91
92 // ------------------------------------------------------------- Properties
93
94
95 /**
96 * The context-relative URL (starting with '/') of the resource to be
97 * forwarded to.
98 */
99 protected String page = null;
100
101 public String getPage() {
102 return (this.page);
103 }
104
105 public void setPage(String page) {
106 this.page = page;
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 // Get the actual resource reference we will be using
130 String resource = page;
131 if (resource == null) {
132 try {
133 resource = (String) webContext.pop();
134 } catch (EmptyStackException e) {
135 throw new StepException("Evaluation stack is empty", this);
136 }
137 }
138
139 // Create a request dispatcher for this resource
140 RequestDispatcher rd =
141 webContext.getServletContext().getRequestDispatcher(resource);
142 if (rd == null)
143 throw new StepException("No request dispatcher for '" +
144 resource + "'", this);
145 ServletRequest request = webContext.getServletRequest();
146 ServletResponse response = webContext.getServletResponse();
147
148 // Forward to the requested resource
149 try {
150 rd.forward(request, response);
151 } catch (IOException e) {
152 throw new StepException("IOException forwarding to '" +
153 resource + "'", e, this);
154 } catch (ServletException e) {
155 throw new StepException("ServletException forwarding to '" +
156 resource + "'", e, this);
157 }
158
159 // Signal our Context to suspend execution
160 context.setSuspend(true);
161
162 }
163
164
165 /**
166 * Render a string representation of this Step.
167 */
168 public String toString() {
169
170 StringBuffer sb = new StringBuffer("<web:forward");
171 if (getId() != null) {
172 sb.append(" id=\"");
173 sb.append(getId());
174 sb.append("\"");
175 }
176 sb.append(" page=\"");
177 sb.append(getPage());
178 sb.append("\"/>");
179 return (sb.toString());
180
181 }
182
183
184 }