ServletContextAttributeExporter


1   /*
2    * Copyright 2002-2005 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.context.support;
18  
19  import java.util.Iterator  ;
20  import java.util.Map  ;
21  
22  import javax.servlet.ServletContext  ;
23  
24  import org.apache.commons.logging.Log;
25  import org.apache.commons.logging.LogFactory;
26  
27  import org.springframework.web.context.ServletContextAware;
28  
29  /**
30   * Exporter that takes Spring-defined objects and exposes them as
31   * ServletContext attributes. Usually, bean references will be used
32   * to export Spring-defined beans as ServletContext attributes.
33   *
34   * <p>Useful to make Spring-defined beans available to code that is
35   * not aware of Spring at all, but rather just of the Servlet API.
36   * Client code can then use plain ServletContext attribute lookups
37   * to access those objects, despite them being defined in a Spring
38   * application context.
39   *
40   * <p>Alternatively, consider using the WebApplicationContextUtils
41   * class to access Spring-defined beans via the WebApplicationContext
42   * interface. This makes client code aware of Spring API, of course.
43   *
44   * @author Juergen Hoeller
45   * @since 1.1.4
46   * @see javax.servlet.ServletContext#getAttribute
47   * @see WebApplicationContextUtils#getWebApplicationContext
48   */
49  public class ServletContextAttributeExporter implements ServletContextAware {
50  
51      protected final Log logger = LogFactory.getLog(getClass());
52  
53      private Map   attributes;
54  
55      /**
56       * Set the ServletContext attributes to expose as key-value pairs.
57       * Each key will be considered a ServletContext attributes key,
58       * and each value will be used as corresponding attribute value.
59       * <p>Usually, you will use bean references for the values,
60       * to export Spring-defined beans as ServletContext attributes.
61       * Of course, it is also possible to define plain values to export.
62       * @param attributes Map with String keys and Object values
63       */
64      public void setAttributes(Map   attributes) {
65          this.attributes = attributes;
66      }
67  
68      public void setServletContext(ServletContext   servletContext) {
69          for (Iterator   it = this.attributes.entrySet().iterator(); it.hasNext();) {
70              Map.Entry   entry = (Map.Entry  ) it.next();
71              String   attributeName = (String  ) entry.getKey();
72              if (logger.isWarnEnabled()) {
73                  if (servletContext.getAttribute(attributeName) != null) {
74                      logger.warn("Overwriting existing ServletContext attribute with name '" + attributeName + "'");
75                  }
76              }
77              servletContext.setAttribute(attributeName, entry.getValue());
78              if (logger.isInfoEnabled()) {
79                  logger.info("Exported ServletContext attribute with name '" + attributeName + "'");
80              }
81          }
82      }
83  
84  }
85
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