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    1   /*
    2    * $Id: Bean.java 768855 2009-04-27 02:09:35Z wesw $
    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   
   22   package org.apache.struts2.components;
   23   
   24   import java.io.Writer;
   25   
   26   import org.apache.struts2.views.annotations.StrutsTag;
   27   import org.apache.struts2.views.annotations.StrutsTagAttribute;
   28   
   29   import com.opensymphony.xwork2.ObjectFactory;
   30   import com.opensymphony.xwork2.inject.Inject;
   31   import com.opensymphony.xwork2.util.ClassLoaderUtil;
   32   import com.opensymphony.xwork2.util.ValueStack;
   33   import com.opensymphony.xwork2.util.logging.Logger;
   34   import com.opensymphony.xwork2.util.logging.LoggerFactory;
   35   import com.opensymphony.xwork2.util.reflection.ReflectionProvider;
   36   
   37   /**
   38    * <!-- START SNIPPET: javadoc -->
   39    * <p>Instantiates a class that conforms to the JavaBeans specification. This tag has a body which can contain
   40    * a number of {@link Param} elements to set any mutator methods on that class.</p>
   41    * <p/>
   42    * <p>If the var attribute is set on the BeanTag, it will place the instantiated bean into the
   43    * stack's Context.</p>
   44    * <p/>
   45    * <!-- END SNIPPET: javadoc -->
   46    *
   47    *
   48    * <!-- START SNIPPET: params -->
   49    * <ul>
   50    *      <li>var - the stack's context name (if supplied) that the created bean will be store under</li>
   51    *      <li>name* - the class name of the bean to be instantiated (must respect JavaBean specification)</li>
   52    * </ul>
   53    * <!-- END SNIPPET: params -->
   54    *
   55    *
   56    * <p>Examples:</p>
   57    * <p/>
   58    * <pre>
   59    * <!-- START SNIPPET: examples -->
   60    * &lt;-- in freemarker form --&gt;
   61    * [@s.bean name="org.apache.struts2.example.counter.SimpleCounter" var="counter"]
   62    *   [s:param name="foo" value="BAR"/]
   63    *   The value of foo is : [s:property value="foo"/], when inside the bean tag.<br />
   64    * [/s:bean]
   65    *
   66    * &lt;-- in jsp form --&gt;
   67    * &lt;s:bean name="org.apache.struts2.example.counter.SimpleCounter" var="counter"&gt;
   68    *   &lt;s:param name="foo" value="BAR" /&gt;
   69    *   The value of foot is : &lt;s:property value="foo"/&gt;, when inside the bean tag &lt;br /&gt;
   70    * &lt;/s:bean&gt;
   71    * <!-- END SNIPPET: examples -->
   72    * </pre>
   73    * <p/>
   74    *
   75    * <!-- START SNIPPET: examplesdescription -->
   76    * <p>This example instantiates a bean called SimpleCounter and sets the foo property (setFoo('BAR')). The
   77    * SimpleCounter object is then pushed onto the Valuestack, which means that we can call its accessor methods (getFoo())
   78    * with the Property tag and get their values.</p>
   79    * <p/>
   80    * <p>In the above example, the id has been set to a value of <i>counter</i>. This means that the SimpleCounter class
   81    * will be placed into the stack's context. You can access the SimpleCounter class using a Struts tag:</p>
   82    * <p/>
   83    * <pre>
   84    * &lt;-- jsp form --&gt;
   85    * &lt;s:property value="#counter" /&gt;
   86    *
   87    * &lt;-- freemarker form --&gt;
   88    * [s:property value="#counter.foo"/]
   89    * </pre>
   90    * <p/>
   91    * <p>In the property tag example, the <i>#</i> tells Ognl to search the context for the SimpleCounter class which has
   92    * an id(key) of <i>counter</i></p>
   93    * <!-- END SNIPPET: examplesdescription -->
   94    *
   95    * @see Param
   96    */
   97   @StrutsTag(name="bean", tldTagClass="org.apache.struts2.views.jsp.BeanTag",
   98           description="Instantiate a JavaBean and place it in the context")
   99   public class Bean extends ContextBean {
  100       protected static final Logger LOG = LoggerFactory.getLogger(Bean.class);
  101   
  102       protected Object bean;
  103       protected String name;
  104       protected ObjectFactory objectFactory;
  105       protected ReflectionProvider reflectionProvider;
  106   
  107       public Bean(ValueStack stack) {
  108           super(stack);
  109       }
  110       
  111       @Inject
  112       public void setObjectFactory(ObjectFactory objectFactory) {
  113           this.objectFactory = objectFactory;
  114       }
  115       
  116       @Inject
  117       public void setReflectionProvider(ReflectionProvider prov) {
  118           this.reflectionProvider = prov;
  119       }
  120   
  121       public boolean start(Writer writer) {
  122           boolean result = super.start(writer);
  123   
  124           ValueStack stack = getStack();
  125   
  126           try {
  127               String beanName = findString(name, "name", "Bean name is required. Example: com.acme.FooBean");
  128               bean = objectFactory.buildBean(ClassLoaderUtil.loadClass(beanName, getClass()), stack.getContext());
  129           } catch (Exception e) {
  130               LOG.error("Could not instantiate bean", e);
  131   
  132               return false;
  133           }
  134   
  135           // push bean on stack
  136           stack.push(bean);
  137   
  138           // store for reference later
  139           putInContext(bean);
  140   
  141           return result;
  142       }
  143   
  144       public boolean end(Writer writer, String body) {
  145           ValueStack stack = getStack();
  146           stack.pop();
  147   
  148           return super.end(writer, body);
  149       }
  150   
  151       public void addParameter(String key, Object value) {
  152           reflectionProvider.setProperty(key, value, bean, getStack().getContext());
  153       }
  154   
  155       @StrutsTagAttribute(description="The class name of the bean to be instantiated (must respect JavaBean specification)",
  156                           required=true)
  157       public void setName(String name) {
  158           this.name = name;
  159       }
  160   }

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