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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.servlet;
22  
23  import java.lang.reflect.Method;
24  
25  import jakarta.servlet.http.HttpServletRequest;
26  import jakarta.servlet.http.HttpServletResponse;
27  
28  import org.apache.struts.action.Action;
29  import org.apache.struts.action.ActionForm;
30  import org.apache.struts.action.ActionMapping;
31  import org.apache.struts.chain.contexts.ActionContext;
32  import org.apache.struts.chain.contexts.ServletActionContext;
33  import org.apache.struts.config.ActionConfig;
34  import org.apache.struts.dispatcher.AbstractMethodResolver;
35  
36  /**
37   * This class helps resolve methods with servlet-based signatures. The following
38   * examples illustrate the method signatures supported:
39   * <ul>
40   * <li><code><i>return_type</i> execute()</code></li>
41   * <li><code><i>return_type</i> execute(ActionContext context)</code></li>
42   * <li><code><i>return_type</i> execute(ServletActionContext context)</code></li>
43   * <li><code><i>return_type</i> execute(ActionMapping mapping, ActionForm form,
44   HttpServletRequest request, HttpServletResponse response)</code></li>
45   * </ul>
46   *
47   * @version $Rev$
48   * @since Struts 1.4
49   */
50  public class ServletMethodResolver extends AbstractMethodResolver {
51      private static final long serialVersionUID = -4372320855532463910L;
52  
53      /**
54       * The set of argument type classes for the classic reflected method call.
55       * These are the same for all calls, so calculate them only once.
56       *
57       * @see org.apache.struts.action.Action#execute(ActionMapping, ActionForm,
58       *      jakarta.servlet.ServletRequest, jakarta.servlet.ServletResponse)
59       */
60      private static final Class<?>[] CLASSIC_EXECUTE_SIGNATURE = { ActionMapping.class, ActionForm.class,
61              HttpServletRequest.class, HttpServletResponse.class };
62  
63      public Object[] buildArguments(ActionContext context, Method method) {
64          Object[] args = super.buildArguments(context, method);
65          if (args == null) {
66              Class<?>[] parameterTypes = method.getParameterTypes();
67              switch (parameterTypes.length) {
68              case 4:
69                  return buildClassicArguments((ServletActionContext) context);
70              default:
71                  break;
72              }
73          }
74          return args;
75      }
76  
77      /**
78       * Constructs the arguments to invoke the classic <code>execute</code>
79       * servlet signature from the specified context.
80       *
81       * @param context the current context
82       * @return the arguments array
83       * @throws NullPointerException if context is <code>null</code>
84       * @see #resolveClassicMethod(ActionContext, String)
85       */
86      protected final Object[] buildClassicArguments(ServletActionContext context) {
87          ActionConfig mapping = context.getActionConfig();
88          ActionForm form = context.getActionForm();
89          HttpServletRequest request = context.getRequest();
90          HttpServletResponse response = context.getResponse();
91          return new Object[] { mapping, form, request, response };
92      }
93  
94      /**
95       * Obtains the method instance with the classic <code>execute</code>
96       * servlet signature.
97       *
98       * @param context the current context
99       * @param methodName the method name to introspect
100      * @return the found method in the action
101      * @throws NullPointerException if context is <code>null</code>
102      * @throws NoSuchMethodException if the method does not exist
103      * @see #buildClassicArguments(ServletActionContext)
104      * @see org.apache.struts.action.Action#execute(ActionMapping, ActionForm,
105      *      jakarta.servlet.ServletRequest, jakarta.servlet.ServletResponse)
106      */
107     protected final Method resolveClassicMethod(ActionContext context, String methodName) throws NoSuchMethodException {
108         Class<? extends Action> actionClass = context.getAction().getClass();
109         return actionClass.getMethod(methodName, CLASSIC_EXECUTE_SIGNATURE);
110     }
111 
112     public Method resolveMethod(ActionContext context, String methodName) throws NoSuchMethodException {
113         // First try to resolve anything the superclass supports
114         try {
115             return super.resolveMethod(context, methodName);
116         } catch (NoSuchMethodException e) {
117             // continue
118         }
119 
120         // Can the method accept the servlet action context?
121         if (context instanceof ServletActionContext) {
122             try {
123                 Class<? extends Action> actionClass = context.getAction().getClass();
124                 return actionClass.getMethod(methodName, ServletActionContext.class);
125             } catch (NoSuchMethodException e) {
126                 // continue
127             }
128         }
129 
130         // Lastly, try the classical argument listing
131         return resolveClassicMethod(context, methodName);
132     }
133 }