commons-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From jstrac...@apache.org
Subject cvs commit: jakarta-commons-sandbox/jelly/src/java/org/apache/commons/jelly/tags/core UseBeanTag.java CoreTagLibrary.java
Date Tue, 24 Sep 2002 11:38:53 GMT
jstrachan    2002/09/24 04:38:53

  Modified:    jelly/src/java/org/apache/commons/jelly/tags/core
                        CoreTagLibrary.java
  Added:       jelly/src/java/org/apache/commons/jelly/tags/core
                        UseBeanTag.java
  Log:
  Added a <j:useBean> tag to both mimick the similar JSP tag but also to combine it
with the <j:setProperties> tag so that a fully configured bean can be created easily
by a single tag.
  
  <j:useBean var="foo" class="com.acme.MyCustomer" name="James" location="London" role="Hacker"/>
  
  Where the above will create a new variable called 'foo' of type com.acme.MyCustomer and
then will set the name, location and role properties to the values given.
  
  This tag is also useful as a base class for constructing arbitrary objects of certain kinds
that can be configured and used in some script - such as to plug in arbitrary Actions into
a workflow style script or in a simple testing framework etc.
  
  Revision  Changes    Path
  1.16      +6 -5      jakarta-commons-sandbox/jelly/src/java/org/apache/commons/jelly/tags/core/CoreTagLibrary.java
  
  Index: CoreTagLibrary.java
  ===================================================================
  RCS file: /home/cvs/jakarta-commons-sandbox/jelly/src/java/org/apache/commons/jelly/tags/core/CoreTagLibrary.java,v
  retrieving revision 1.15
  retrieving revision 1.16
  diff -u -r1.15 -r1.16
  --- CoreTagLibrary.java	24 Sep 2002 10:55:59 -0000	1.15
  +++ CoreTagLibrary.java	24 Sep 2002 11:38:53 -0000	1.16
  @@ -100,6 +100,7 @@
           registerTag("expr", ExprTag.class);
           registerTag("new", NewTag.class);
           registerTag("setProperties", SetPropertiesTag.class);
  +        registerTag("useBean", UseBeanTag.class);
           registerTag("whitespace", WhitespaceTag.class);
           registerTag("thread", ThreadTag.class);
           registerTag("file", FileTag.class);
  
  
  
  1.1                  jakarta-commons-sandbox/jelly/src/java/org/apache/commons/jelly/tags/core/UseBeanTag.java
  
  Index: UseBeanTag.java
  ===================================================================
  /*
   * 
   * ====================================================================
   *
   * The Apache Software License, Version 1.1
   *
   * Copyright (c) 1999-2002 The Apache Software Foundation.  All rights
   * reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   *
   * 3. The end-user documentation included with the redistribution, if
   *    any, must include the following acknowlegement:
   *       "This product includes software developed by the
   *        Apache Software Foundation (http://www.apache.org/)."
   *    Alternately, this acknowlegement may appear in the software itself,
   *    if and wherever such third-party acknowlegements normally appear.
   *
   * 4. The names "The Jakarta Project", "Commons", and "Apache Software
   *    Foundation" must not be used to endorse or promote products derived
   *    from this software without prior written permission. For written
   *    permission, please contact apache@apache.org.
   *
   * 5. Products derived from this software may not be called "Apache"
   *    nor may "Apache" appear in their names without prior written
   *    permission of the Apache Group.
   *
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
   * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
   * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
   * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
   * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   */
  package org.apache.commons.jelly.tags.core;
  
  import java.util.Map;
  
  import org.apache.commons.beanutils.BeanUtils;
  
  import org.apache.commons.jelly.MissingAttributeException;
  import org.apache.commons.jelly.MapTagSupport;
  import org.apache.commons.jelly.XMLOutput;
  
  /** 
   * A tag which instantiates an instance of the given class
   * and then sets the properties on the bean.
   * The class can be specified via a {@link java.lang.Class} instance or
   * a String which will be used to load the class using either the current
   * thread's context class loader or the class loader used to load this
   * Jelly library.
   * 
   * This tag can be used it as follows, 
   * <pre>
   * &lt;j:useBean var="person" class="com.acme.Person" name="James" location="${loc}"/&gt;
   * &lt;j:useBean var="order" class="${orderClass}" amount="12" price="123.456"/&gt;
   * </pre>
   * 
   * @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
   * @version $Revision: 1.3 $
   */
  public class UseBeanTag extends MapTagSupport  {
  
      public UseBeanTag(){
      }
  
      // Tag interface
      //-------------------------------------------------------------------------        
           
      public void doTag(XMLOutput output) throws Exception {
          Map attributes = getAttributes();
          String var = (String) attributes.get( "var" );
          Object classObject = attributes.remove( "class" );
          if ( classObject == null ) {
              throw new MissingAttributeException("class");
          }
          Class theClass = convertToClass(classObject);
          Object bean = newInstance(theClass, attributes);
          setBeanProperties(bean, attributes);
          processBean(var, bean);
      }
  
      // Implementation methods
      //-------------------------------------------------------------------------        
           
  
      /**
       * Attempts to convert the given object to a Class instance.
       * If the classObject is already a Class it will be returned 
       * otherwise it will be converted to a String and loaded
       * using the default class loading mechanism.
       */
      protected Class convertToClass(Object classObject) throws Exception {
          if (classObject instanceof Class) {
              return (Class) classObject;
          }
          else {
              String className = classObject.toString();
              return loadClass(className);
          }
      }
  
      /**
       * Loads the given class using the default class loading mechanism
       * which is to try use the current Thread's context class loader first
       * otherise use the class loader which loaded this class.
       */    
      protected Class loadClass(String className) throws Exception {
          try {
              return Thread.currentThread().getContextClassLoader().loadClass(className);
          }
          catch (Exception e) {
              return getClass().getClassLoader().loadClass(className);
          }
      }
      
      /**
       * Creates a new instance of the given class, which by default will invoke the
       * default constructor.
       * Derived tags could do something different here.
       */
      protected Object newInstance(Class theClass, Map attributes) throws Exception {
          return theClass.newInstance();
      }
      
      /**
       * Sets the properties on the bean. Derived tags could implement some custom 
       * type conversion etc.
       */
      protected void setBeanProperties(Object bean, Map attributes) throws Exception {
          BeanUtils.populate(bean, attributes);
      }
  
      /**
       * By default this will export the bean using the given variable if it is defined.
       * This Strategy method allows derived tags to process the beans in different ways
       * such as to register this bean with its parent tag etc.
       */
      protected void processBean(String var, Object bean) throws Exception {
          if (var != null) {
              context.setVariable(var, bean);
          }
      }
  }
  
  
  

--
To unsubscribe, e-mail:   <mailto:commons-dev-unsubscribe@jakarta.apache.org>
For additional commands, e-mail: <mailto:commons-dev-help@jakarta.apache.org>


Mime
View raw message