1 /*
2 * $Id$
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.dispatcher;
22
23 import org.apache.struts.action.ActionMapping;
24 import org.apache.struts.chain.contexts.ActionContext;
25
26 import java.util.StringTokenizer;
27
28 /**
29 * This abstract class is a template for choosing the target method that is
30 * named in the list-encoded <code>parameter</code> attribute of the
31 * {@link ActionMapping} that matches a submission parameter. This is useful for
32 * developers who prefer to use many submit buttons, images, or submit links on
33 * a single form and whose related actions exist in a single action.
34 * <p>
35 * For utility purposes, you can use the <code>key=value</code> notation to
36 * alias methods so that they are exposed as different form element names, in
37 * the event of a naming conflict or otherwise. In this example, the
38 * <em>recalc</em> button (via a submission parameter) will invoke the
39 * <code>recalculate</code> method. The security-minded person may find this
40 * feature valuable to obfuscate and not expose the methods.
41 * <p>
42 * The <em>default</em> key is purely optional, but encouraged when nothing
43 * matches (such as the user pressing the enter key). If this is not specified
44 * and no parameters match the list of method keys, the method resolution
45 * returns <code>null</code>.
46 * <p>
47 * The order of the parameters are guaranteed to be iterated in the order
48 * specified. If multiple buttons were accidently submitted, the first match in
49 * the list will be dispatched.
50 *
51 * @version $Rev$
52 * @since Struts 1.4
53 */
54 public abstract class AbstractEventMappingDispatcher extends AbstractMappingDispatcher {
55 private static final long serialVersionUID = -8559616664806617100L;
56
57 /**
58 * The method key, if present, to use if other specified method keys do not
59 * match a request parameter.
60 */
61 protected static final String DEFAULT_METHOD_KEY = "default";
62
63 /**
64 * Constructs a new dispatcher with the specified method resolver.
65 *
66 * @param methodResolver the method resolver
67 */
68 public AbstractEventMappingDispatcher(MethodResolver methodResolver) {
69 super(methodResolver);
70 }
71
72 /**
73 * Determines whether the specified method key is a submission parameter.
74 *
75 * @param context the current action context
76 * @param methodKey the method key
77 * @return <code>true</code> if match; otherwise <code>false</code>
78 * @see #resolveMethodName(ActionContext)
79 */
80 protected abstract boolean isSubmissionParameter(ActionContext context, String methodKey);
81
82 protected final String resolveMethodName(ActionContext context) {
83 // Obtain the mapping parameter
84 String mappingParameter = super.resolveMethodName(context);
85 if (mappingParameter == null) {
86 return null;
87 }
88
89 // Parse it as a comma-separated list
90 StringTokenizer st = new StringTokenizer(mappingParameter, ",");
91 String defaultMethodName = null;
92
93 while (st.hasMoreTokens()) {
94 String methodKey = st.nextToken().trim();
95 String methodName = methodKey;
96
97 // The key can either be a direct method name or an alias
98 // to a method as indicated by a "key=value" signature
99 int equals = methodKey.indexOf('=');
100 if (equals > -1) {
101 methodName = methodKey.substring(equals + 1).trim();
102 methodKey = methodKey.substring(0, equals).trim();
103 }
104
105 // Set the default if it passes by
106 if (methodKey.equals(DEFAULT_METHOD_KEY)) {
107 defaultMethodName = methodName;
108 }
109
110 // Is it a match?
111 if (isSubmissionParameter(context, methodKey)) {
112 return methodName;
113 }
114 }
115
116 return defaultMethodName;
117 }
118
119 }