reloadabledefinitionsfactory.java

这是一个轻便的j2ee的web应用框架,是一个在多个项目中运用的实际框架,采用struts,hebinate,xml等技术,有丰富的tag,role,navigation,session,dictio

/*
 * $Header: /sfroot/cvs/esimple/src/core/org/apache/struts/tiles/definition/ReloadableDefinitionsFactory.java,v 1.1.1.1 2004/09/08 06:38:38 lava Exp $
 * $Revision: 1.1.1.1 $
 * $Date: 2004/09/08 06:38:38 $
 *
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
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 * reserved.
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 * modification, are permitted provided that the following conditions
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 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
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package org.apache.struts.tiles.definition;

import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;

import org.apache.struts.tiles.ComponentDefinition;
import org.apache.struts.tiles.ComponentDefinitionsFactory;
import org.apache.struts.tiles.DefinitionsFactoryException;
import org.apache.struts.tiles.FactoryNotFoundException;
import org.apache.struts.tiles.xmlDefinition.I18nFactorySet;
import org.apache.struts.tiles.TilesUtil;

/**
 * A reloadable factory.
 * This factory is the main entrance to any factory implementation. It takes in
 * charge real implementation instance, and allows reloading by creating a new
 * instance.
 *
 * @author Cedric Dumoulin
 * @since 1.1
 * @version $Revision: 1.1.1.1 $ $Date: 2004/09/08 06:38:38 $
 */
public class ReloadableDefinitionsFactory implements ComponentDefinitionsFactory
{
    /** The real factory instance */
  protected ComponentDefinitionsFactory factory;
    /** Initialization parameters */
  protected Map properties;

    /** Name of init property carrying factory class name */
  public static final String DEFINITIONS_FACTORY_CLASSNAME = "definitions-factory-class";

    /**
     * Constructor.
     * Create a factory according to servlet settings.
     * @param servletContext Our servlet context.
     * @param servletConfig Our servlet config.
     * @throws DefinitionsFactoryException If factory creation fail.
     */
  public ReloadableDefinitionsFactory( ServletContext servletContext, ServletConfig servletConfig )
    throws DefinitionsFactoryException
  {
  properties = new ServletPropertiesMap( servletConfig );
  factory = createFactory( servletContext, properties);
  }

    /**
     * Constructor.
     * Create a factory according to servlet settings.
     * @param servletContext Our servlet context.
     * @param properties Map containing all properties.
     * @throws DefinitionsFactoryException If factory creation fail.
     */
  public ReloadableDefinitionsFactory( ServletContext servletContext, Map properties )
    throws DefinitionsFactoryException
  {
  this.properties = properties;
  factory = createFactory( servletContext, properties);
  }


   /**
   * Create Definition factory from provided classname.
   * If a factory class name is provided, a factory of this class is created. Otherwise,
   * a default factory is created.
   * Factory must have a constructor taking ServletContext and Map as parameter.
   * @param classname Class name of the factory to create.
   * @param servletContext Servlet Context passed to newly created factory.
   * @param properties Map of name/property passed to newly created factory.
   * @return newly created factory.
   * @throws DefinitionsFactoryException If an error occur while initializing factory
   */
  public ComponentDefinitionsFactory createFactoryFromClassname(ServletContext servletContext, Map properties, String classname)
    throws DefinitionsFactoryException
  {
  if( classname == null )
    return createFactory( servletContext, properties );

    // Try to create from classname
  try
    {
    Class factoryClass = TilesUtil.applicationClass(classname);
    ComponentDefinitionsFactory factory = (ComponentDefinitionsFactory)factoryClass.newInstance();
    factory.initFactory( servletContext, properties);
    return factory;
    }
   catch( ClassCastException ex )
    { // Bad classname
    throw new DefinitionsFactoryException( "Error - createDefinitionsFactory : Factory class '"
                                           + classname +" must implements 'ComponentDefinitionsFactory'.", ex );
    }
   catch( ClassNotFoundException ex )
    { // Bad classname
    throw new DefinitionsFactoryException( "Error - createDefinitionsFactory : Bad class name '"
                                           + classname +"'.", ex );
    }
   catch( InstantiationException ex )
    { // Bad constructor or error
    throw new DefinitionsFactoryException( ex );
    }
   catch( IllegalAccessException ex )
    { //
    throw new DefinitionsFactoryException( ex );
    }

  }

   /**
   * Create default Definition factory.
   * Factory must have a constructor taking ServletContext and Map as parameter.
   * In this implementation, default factory is of class I18nFactorySet
   * @param servletContext Servlet Context passed to newly created factory.
   * @param properties Map of name/property passed to newly created factory.
   * @return newly created factory.
   * @throws DefinitionsFactoryException If an error occur while initializing factory
   */
  public ComponentDefinitionsFactory createDefaultFactory(ServletContext servletContext, Map properties)
    throws DefinitionsFactoryException
  {
    ComponentDefinitionsFactory factory = new I18nFactorySet(servletContext, properties); ;
    return factory;
  }

   /**
   * Create Definition factory.
   * Convenience method. ServletConfig is wrapped into a Map allowing retrieval
   * of init parameters. Factory classname is also retrieved, as well as debug level.
   * Finally, approriate createDefinitionsFactory() is called.
   * @param servletContext Servlet Context passed to newly created factory.
   * @param properties Map containing all properties.
   */
  public ComponentDefinitionsFactory createFactory(ServletContext servletContext, Map properties)
    throws DefinitionsFactoryException
  {
    String classname = (String)properties.get(DEFINITIONS_FACTORY_CLASSNAME);
    if(classname!=null)
      return createFactoryFromClassname( servletContext, properties, classname);

    return new I18nFactorySet( servletContext, properties );
  }


  /**
   * Get a definition by its name.
   * Call appropriate method on underlying factory instance.
   * Throw appropriate exception if definition or definition factory is not found.
   * @param definitionName Name of requested definition.
   * @param request Current servlet request.
   * @param servletContext Current servlet context.
   * @throws FactoryNotFoundException Can't find definition factory.
   * @throws DefinitionsFactoryException General error in factory while getting definition.
   */
  public ComponentDefinition getDefinition(String definitionName, ServletRequest request, ServletContext servletContext)
    throws FactoryNotFoundException, DefinitionsFactoryException
  {
  return factory.getDefinition(definitionName, (HttpServletRequest)request, servletContext);
  }

  /**
   * Reload underlying factory.
   * Reload is done by creating a new factory instance, and replacing the old instance
   * with the new one.
   * @param servletContext Current servlet context.
   * @throws DefinitionsFactoryException If factory creation fails.
   */
  public void reload(ServletContext servletContext)
    throws DefinitionsFactoryException
  {
  ComponentDefinitionsFactory newInstance = createFactory( servletContext, properties);
  factory = newInstance;
  }

  /**
   * Get underlying factory instance.
   * @return ComponentDefinitionsFactory
   */
  public ComponentDefinitionsFactory getFactory()
  {
  return factory;
  }

   /**
     * Init factory.
     * This method is required by interface ComponentDefinitionsFactory. It is
     * not used in this implementation, as it manages itself the underlying creation
     * and initialization.
     * @param servletContext Servlet Context passed to newly created factory.
     * @param properties Map of name/property passed to newly created factory.
     * Map can contain more properties than requested.
     * @throws DefinitionsFactoryException An error occur during initialization.
   */
   public void initFactory(ServletContext servletContext, Map properties) throws DefinitionsFactoryException
   {  // do nothing
   }

   /**
    * Return String representation.
    * @return String representation.
    */
   public String toString()
   {
   return factory.toString();
   }

  /**
   * Inner class.
   * Wrapper for ServletContext init parameters.
   * Object of this class is an HashMap containing parameters and values
   * defined in the servlet config file (web.xml).
   */
 class ServletPropertiesMap extends HashMap {
    /**
     * Constructor.
     */
  ServletPropertiesMap( ServletConfig config )
    {
      // This implementation is very simple.
      // It is possible to avoid creation of a new structure, but this would
      // imply writing all of the Map interface.
    Enumeration enum = config.getInitParameterNames();
    while( enum.hasMoreElements() )
      {
      String key = (String)enum.nextElement();
      put( key, config.getInitParameter( key ) );
      }
    }
}  // end inner class
}