AutowiringRequestProcessor


1   /*
2    * Copyright 2002-2006 the original author or authors.
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.springframework.web.struts;
18  
19  import java.io.IOException  ;
20  
21  import javax.servlet.ServletException  ;
22  import javax.servlet.http.HttpServletRequest  ;
23  import javax.servlet.http.HttpServletResponse  ;
24  
25  import org.apache.struts.action.Action;
26  import org.apache.struts.action.ActionMapping;
27  import org.apache.struts.action.ActionServlet;
28  import org.apache.struts.action.RequestProcessor;
29  import org.apache.struts.config.ModuleConfig;
30  
31  import org.springframework.beans.factory.config.AutowireCapableBeanFactory;
32  import org.springframework.context.ConfigurableApplicationContext;
33  import org.springframework.web.context.WebApplicationContext;
34  
35  /**
36   * Subclass of Struts's default RequestProcessor that autowires Struts Actions
37   * with Spring beans defined in ContextLoaderPlugIn's WebApplicationContext
38   * or - in case of general service layer beans - in the root WebApplicationContext.
39   *
40   * <p>In the Struts config file, you simply continue to specify the original
41   * Action class. The instance created for that class will automatically get
42   * wired with matching service layer beans, that is, bean property setters
43   * will automatically be called if a service layer bean matches the property.
44   *
45   * <pre>
46   * &lt;action path="/login" type="myapp.MyAction"/&gt;</pre>
47   *
48   * There are two autowire modes available: "byType" and "byName". The default
49   * is "byType", matching service layer beans with the Action's bean property
50   * argument types. This behavior can be changed through specifying an "autowire"
51   * init-param for the Struts ActionServlet with the value "byName", which will
52   * match service layer bean names with the Action's bean property <i>names</i>.
53   *
54   * <p>Dependency checking is turned off by default: If no matching service
55   * layer bean can be found, the setter in question will simply not get invoked.
56   * To enforce matching service layer beans, consider specify the "dependencyCheck"
57   * init-param for the Struts ActionServlet with the value "true".
58   *
59   * <p>If you also need the Tiles setup functionality of the original
60   * TilesRequestProcessor, use AutowiringTilesRequestProcessor. As there's just
61   * a single central class to customize in Struts, we have to provide another
62   * subclass here, covering both the Tiles and the Spring delegation aspect.
63   *
64   * <p>The default implementation delegates to the DelegatingActionUtils
65   * class as fas as possible, to reuse as much code as possible despite
66   * the need to provide two RequestProcessor subclasses. If you need to
67   * subclass yet another RequestProcessor, take this class as a template,
68   * delegating to DelegatingActionUtils just like it.
69   *
70   * @author Juergen Hoeller
71   * @since 2.0
72   * @see AutowiringTilesRequestProcessor
73   * @see ContextLoaderPlugIn
74   * @see DelegatingActionUtils
75   */
76  public class AutowiringRequestProcessor extends RequestProcessor {
77  
78      private WebApplicationContext webApplicationContext;
79  
80      private int autowireMode = AutowireCapableBeanFactory.AUTOWIRE_NO;
81  
82      private boolean dependencyCheck = false;
83  
84  
85      public void init(ActionServlet actionServlet, ModuleConfig moduleConfig) throws ServletException   {
86          super.init(actionServlet, moduleConfig);
87          if (actionServlet != null) {
88              this.webApplicationContext = initWebApplicationContext(actionServlet, moduleConfig);
89              this.autowireMode = initAutowireMode(actionServlet, moduleConfig);
90              this.dependencyCheck = initDependencyCheck(actionServlet, moduleConfig);
91          }
92      }
93  
94      /**
95       * Fetch ContextLoaderPlugIn's WebApplicationContext from the ServletContext,
96       * falling back to the root WebApplicationContext. This context is supposed
97       * to contain the service layer beans to wire the Struts Actions with.
98       * @param actionServlet the associated ActionServlet
99       * @param moduleConfig the associated ModuleConfig
100      * @return the WebApplicationContext
101      * @throws IllegalStateException if no WebApplicationContext could be found
102      * @see DelegatingActionUtils#findRequiredWebApplicationContext
103      * @see ContextLoaderPlugIn#SERVLET_CONTEXT_PREFIX
104      */
105     protected WebApplicationContext initWebApplicationContext(
106             ActionServlet actionServlet, ModuleConfig moduleConfig) throws IllegalStateException   {
107 
108         WebApplicationContext wac =
109                 DelegatingActionUtils.findRequiredWebApplicationContext(actionServlet, moduleConfig);
110         if (wac instanceof ConfigurableApplicationContext) {
111             ((ConfigurableApplicationContext) wac).getBeanFactory().ignoreDependencyType(ActionServlet.class);
112         }
113         return wac;
114     }
115 
116     /**
117      * Determine the autowire mode to use for wiring Struts Actions.
118      * <p>The default implementation checks the "autowire" init-param of the
119      * Struts ActionServlet, falling back to "AUTOWIRE_BY_TYPE" as default.
120      * @param actionServlet the associated ActionServlet
121      * @param moduleConfig the associated ModuleConfig
122      * @return the autowire mode to use
123      * @see DelegatingActionUtils#getAutowireMode
124      * @see org.springframework.beans.factory.config.AutowireCapableBeanFactory#autowireBeanProperties
125      * @see org.springframework.beans.factory.config.AutowireCapableBeanFactory#AUTOWIRE_BY_TYPE
126      * @see org.springframework.beans.factory.config.AutowireCapableBeanFactory#AUTOWIRE_BY_NAME
127      */
128     protected int initAutowireMode(ActionServlet actionServlet, ModuleConfig moduleConfig) {
129         return DelegatingActionUtils.getAutowireMode(actionServlet);
130     }
131 
132     /**
133      * Determine whether to apply a dependency check after wiring Struts Actions.
134      * <p>The default implementation checks the "dependencyCheck" init-param of the
135      * Struts ActionServlet, falling back to no dependency check as default.
136      * @param actionServlet the associated ActionServlet
137      * @param moduleConfig the associated ModuleConfig
138      * @return whether to enforce a dependency check or not
139      * @see DelegatingActionUtils#getDependencyCheck
140      * @see org.springframework.beans.factory.config.AutowireCapableBeanFactory#autowireBeanProperties
141      */
142     protected boolean initDependencyCheck(ActionServlet actionServlet, ModuleConfig moduleConfig) {
143         return DelegatingActionUtils.getDependencyCheck(actionServlet);
144     }
145 
146 
147     /**
148      * Return the current Spring WebApplicationContext.
149      */
150     protected final WebApplicationContext getWebApplicationContext() {
151         return this.webApplicationContext;
152     }
153 
154     /**
155      * Return the autowire mode to use for wiring Struts Actions.
156      */
157     protected final int getAutowireMode() {
158         return autowireMode;
159     }
160 
161     /**
162      * Return whether to apply a dependency check after wiring Struts Actions.
163      */
164     protected final boolean getDependencyCheck() {
165         return dependencyCheck;
166     }
167 
168 
169     /**
170      * Extend the base class method to autowire each created Action instance.
171      * @see org.springframework.beans.factory.config.AutowireCapableBeanFactory#autowireBeanProperties
172      */
173     protected Action processActionCreate(
174             HttpServletRequest   request, HttpServletResponse   response, ActionMapping mapping)
175             throws IOException   {
176 
177         Action action = super.processActionCreate(request, response, mapping);
178         getWebApplicationContext().getAutowireCapableBeanFactory().autowireBeanProperties(
179                 action, getAutowireMode(), getDependencyCheck());
180         return action;
181     }
182 
183 }
184
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