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From rdon...@apache.org
Subject cvs commit: jakarta-commons/digester/src/java/org/apache/commons/digester/plugins PluginDeclarationRule.java
Date Sat, 04 Oct 2003 12:29:02 GMT
rdonkin     2003/10/04 05:29:01

  Added:       digester/src/java/org/apache/commons/digester/plugins
                        PluginDeclarationRule.java
  Log:
  Added plugins module. Submitted by Simon Kitching.
  
  Revision  Changes    Path
  1.1                  jakarta-commons/digester/src/java/org/apache/commons/digester/plugins/PluginDeclarationRule.java
  
  Index: PluginDeclarationRule.java
  ===================================================================
  /*
   *  ====================================================================
   *
   *  The Apache Software License, Version 1.1
   *
   *  Copyright (c) 1999-2003 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.digester.plugins;
  
  import java.io.File;
  
  import org.apache.commons.digester.Rule;
  import org.apache.commons.digester.Digester;
  import org.apache.commons.beanutils.MethodUtils;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  
  /**
   * A Digester rule which allows the user to pre-declare a class which is to
   * be referenced later at a plugin point by a PluginCreateRule.
   * <p>
   * Normally, a PluginDeclarationRule is added to a Digester instance with
   * the pattern "{root}/plugin" or "* /plugin" where {root} is the name of 
   * the root tag in the input document.
   *
   * @author Simon Kitching
   */
  
  public class PluginDeclarationRule extends Rule {
      private static Log log = LogFactory.getLog(PluginDeclarationRule.class);
  
      //------------------- constructors ---------------------------------------
  
      /** constructor  */
      public PluginDeclarationRule() {
          super();
      }
  
      //------------------- methods --------------------------------------------
  
      /**
       * Invoked upon reading a tag defining a plugin declaration. The tag
       * must have the following mandatory attributes:
       * <ul>
       *   <li> id </li>
       *   <li> class </li>
       * </ul>
       *
       *@param namespace The xml namespace in which the xml element which
       * triggered this rule resides.
       *@param name The name of the xml element which triggered this rule.
       *@param attributes The set of attributes on the xml element which
       * triggered this rule.
       *@exception java.lang.Exception
       */
  
      public void begin(
              String namespace,
              String name,
              org.xml.sax.Attributes attributes)
               throws java.lang.Exception {
          String id = attributes.getValue("id");
          String pluginClassName = attributes.getValue("class");
          String ruleMethodName = attributes.getValue("method");
          String ruleClassName = attributes.getValue("ruleclass");
          String ruleResource = attributes.getValue("resource");
          String ruleFile = attributes.getValue("file");
          String autoSetPropertiesStr = attributes.getValue("setprops");
  
          if (log.isDebugEnabled()) {
              log.debug(
                  "mapping id [" + id + "] -> [" + pluginClassName + "]");
          }
  
          if (id == null) {
              throw new ClassNotFoundException(
                      "mandatory attribute id not present on tag"
                       + " <" + name + ">");
          }
  
          if (pluginClassName == null) {
              throw new ClassNotFoundException(
                      "mandatory attribute class not present on tag"
                       + " <" + name + ">");
          }
  
          Declaration newDecl = new Declaration(pluginClassName);
          newDecl.setId(id);
          
          if (ruleMethodName != null) {
              newDecl.setRuleMethod(ruleMethodName);
          }
          
          if (ruleClassName != null) {
              Class ruleClass;
              try {
                  ruleClass = digester.getClassLoader().loadClass(ruleClassName);
              }
              catch(ClassNotFoundException cnfe) {
                  throw new ClassNotFoundException(
                      "Rule class [" + ruleClassName + "] not found.");
              }
              newDecl.setRuleClass(ruleClass);
          }
          
          if (ruleResource != null) {
              newDecl.setRuleResource(ruleResource);
          }
          
          if (ruleFile != null) {
              newDecl.setRuleFile(new File(ruleFile));
          }
          
          if (autoSetPropertiesStr != null) {
              newDecl.setAutoSetProperties(
                  Boolean.valueOf(autoSetPropertiesStr).booleanValue());
          }
          
          newDecl.init(digester);
  
          PluginRules rc = (PluginRules) digester.getRules();
          PluginManager pm = rc.getPluginManager();
          Declaration oldDecl = pm.getDeclarationById(id);
          if (oldDecl != null) {
              if (oldDecl.isEquivalent(newDecl)) {
                  // this is a redeclaration of the same plugin mapping.
                  // this could happen when using xml Entities to include
                  // external files into the main config file, or to include
                  // the same external file at multiple locations within a
                  // parent document. if the declaration is identical,
                  // then we just ignore it.
                  log.debug("plugin redeclaration is identical: ignoring");
                  return;
              } else {
                  throw new Exception("Plugin id [" + id + "] is not unique");
              }
          }
  
          // check whether this class has already been mapped to a different
          // name. It might be nice someday to allow this but lets keep it
          // simple for now.
          if (pm.getDeclarationByClass(pluginClassName) != null) {
              throw new Exception(
                      "Plugin id [" + id + "] maps to class [" + pluginClassName + "]"
                       + " which has already been mapped by some other id.");
          }
  
          pm.addDeclaration(newDecl);
      }
  }
  
  
  
  

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