1 /*
2 * $Id: EventDispatchAction.java 471754 2006-11-06 14:55:09Z husted $
3 *
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21 package org.apache.struts.actions;
22
23 import java.util.StringTokenizer;
24
25 import javax.servlet.ServletException;
26 import javax.servlet.http.HttpServletRequest;
27 import javax.servlet.http.HttpServletResponse;
28
29 import org.apache.commons.logging.Log;
30 import org.apache.commons.logging.LogFactory;
31 import org.apache.struts.action.ActionForm;
32 import org.apache.struts.action.ActionMapping;
33 import org.apache.struts.action.ActionForward;
34
35 /**
36 * <p>An <strong>Action</strong> that dispatches to to one of the public methods
37 * that are named in the <code>parameter</code> attribute of the corresponding
38 * ActionMapping and matches a submission parameter. This is useful for
39 * developers who prefer to use many submit buttons, images, or submit links
40 * on a single form and whose related actions exist in a single Action class.</p>
41 *
42 * <p>The method(s) must have the same signature (other than method name) of the
43 * standard Action.execute method.</p>
44 *
45 * <p>To configure the use of this action in your
46 * <code>struts-config.xml</code> file, create an entry like this:</p>
47 *
48 * <pre><code>
49 * <action path="/saveSubscription"
50 * type="org.example.SubscriptionAction"
51 * name="subscriptionForm"
52 * scope="request"
53 * input="/subscription.jsp"
54 * parameter="save,back,recalc=recalculate,default=save"/>
55 * </code></pre>
56 *
57 * <p>where <code>parameter</code> contains three possible methods and one
58 * default method if nothing matches (such as the user pressing the enter key).</p>
59 *
60 * <p>For utility purposes, you can use the <code>key=value</code> notation to
61 * alias methods so that they are exposed as different form element names, in the
62 * event of a naming conflict or otherwise. In this example, the <em>recalc</em>
63 * button (via a request parameter) will invoke the <code>recalculate</code>
64 * method. The security-minded person may find this feature valuable to
65 * obfuscate and not expose the methods.</p>
66 *
67 * <p>The <em>default</em> key is purely optional. If this is not specified
68 * and no parameters match the list of method keys, <code>null</code> is
69 * returned which means the <code>unspecified</code> method will be invoked.</p>
70 *
71 * <p>The order of the parameters are guaranteed to be iterated in the order
72 * specified. If multiple buttons were accidently submitted, the first match in
73 * the list will be dispatched.</p>
74 *
75 * @since Struts 1.2.9
76 */
77 public class EventDispatchAction extends DispatchAction {
78
79 /**
80 * Commons Logging instance.
81 */
82 private static final Log LOG = LogFactory.getLog(EventDispatchAction.class);
83
84 /**
85 * The method key, if present, to use if other specified method keys
86 * do not match a request parameter.
87 */
88 private static final String DEFAULT_METHOD_KEY = "default";
89
90 // --------------------------------------------------------- Protected Methods
91
92 /**
93 * Method which is dispatched to when there is no value for specified
94 * request parameter included in the request. Subclasses of
95 * <code>DispatchAction</code> should override this method if they wish to
96 * provide default behavior different than throwing a ServletException.
97 *
98 * @param mapping The ActionMapping used to select this instance
99 * @param form The optional ActionForm bean for this request (if any)
100 * @param request The non-HTTP request we are processing
101 * @param response The non-HTTP response we are creating
102 * @return The forward to which control should be transferred, or
103 * <code>null</code> if the response has been completed.
104 * @throws Exception if the application business logic throws an
105 * exception.
106 */
107 protected ActionForward unspecified(ActionMapping mapping, ActionForm form,
108 HttpServletRequest request, HttpServletResponse response)
109 throws Exception {
110 String message =
111 messages.getMessage("event.parameter", mapping.getPath(),
112 mapping.getParameter());
113
114 LOG.error(message + " " + mapping.getParameter());
115
116 throw new ServletException(message);
117 }
118
119 /**
120 * Returns the method name, given a parameter's value.
121 *
122 * @param mapping The ActionMapping used to select this instance
123 * @param form The optional ActionForm bean for this request (if
124 * any)
125 * @param request The HTTP request we are processing
126 * @param response The HTTP response we are creating
127 * @param parameter The <code>ActionMapping</code> parameter's name
128 * @return The method's name.
129 * @throws Exception if an error occurs.
130 */
131 protected String getMethodName(ActionMapping mapping, ActionForm form,
132 HttpServletRequest request, HttpServletResponse response,
133 String parameter) throws Exception {
134
135 StringTokenizer st = new StringTokenizer(parameter, ",");
136 String defaultMethodName = null;
137
138 while (st.hasMoreTokens()) {
139 String methodKey = st.nextToken().trim();
140 String methodName = methodKey;
141
142 // The key can either be a direct method name or an alias
143 // to a method as indicated by a "key=value" signature
144 int equals = methodKey.indexOf('=');
145 if (equals > -1) {
146 methodName = methodKey.substring(equals + 1).trim();
147 methodKey = methodKey.substring(0, equals).trim();
148 }
149
150 // Set the default if it passes by
151 if (methodKey.equals(DEFAULT_METHOD_KEY)) {
152 defaultMethodName = methodName;
153 }
154
155 // If the method key exists as a standalone parameter or with
156 // the image suffixes (.x/.y), the method name has been found.
157 if ((request.getParameter(methodKey) != null)
158 || (request.getParameter(methodKey + ".x") != null)) {
159 return methodName;
160 }
161 }
162
163 return defaultMethodName;
164 }
165 }