src/java/org/apache/jcs/admin/servlet/JCSAdminServlet.java

package org.apache.jcs.admin.servlet;

/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License")
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.jcs.admin.JCSAdminBean;
import org.apache.jcs.engine.control.CompositeCacheManager;
import org.apache.velocity.Template;
import org.apache.velocity.context.Context;
import org.apache.velocity.servlet.VelocityServlet;

/**
 * A servlet which provides HTTP access to JCS. Allows a summary of regions
 * to be viewed, and removeAll to be run on individual regions or all regions.
 * Also provides the ability to remove items (any number of key arguments can
 * be provided with action 'remove'). Should be initialized with a properties
 * file that provides at least a classpath resource loader. Since this extends
 * VelocityServlet, which uses the singleton model for velocity, it will share
 * configuration with any other Velocity in the same JVM.
 *
 * Initialization in a webapp will look something like this:
 * <pre>
 *  [servlet]
 *      [servlet-name]JCSAdminServlet[/servlet-name]
 *      [servlet-class]org.apache.jcs.admin.servlet.JCSAdminServlet[/servlet-class]
 *      [init-param]
 *          [param-name]properties[/param-name]
 *          [param-value]WEB-INF/conf/JCSAdminServlet.velocity.properties[/param-value]
 *      [/init-param]
 *  [/servlet]
 * </pre>
 *
 * FIXME: It would be nice to use the VelocityEngine model so this can be truly
 *        standalone. Right now if you run it in the same container as, say,
 *        turbine, turbine must be run first to ensure it's config takes
 *        precedence.
 *
 * @version $Id$
 */
public class JCSAdminServlet
    extends VelocityServlet
{
  private static final String DEFAULT_TEMPLATE_NAME =
      "/org/apache/jcs/admin/servlet/JCSAdminServletDefault.vm";

  private static final String REGION_DETAIL_TEMPLATE_NAME =
      "/org/apache/jcs/admin/servlet/JCSAdminServletRegionDetail.vm";

  // Keys for parameters

  private static final String CACHE_NAME_PARAM = "cacheName";

  private static final String ACTION_PARAM = "action";
  private static final String KEY_PARAM = "key";
  private static final String SILENT_PARAM = "silent";

  // Possible values for 'action' parameter

  private static final String CLEAR_ALL_REGIONS_ACTION = "clearAllRegions";
  private static final String CLEAR_REGION_ACTION = "clearRegion";
  private static final String REMOVE_ACTION = "remove";
  private static final String DETAIL_ACTION = "detail";

  private CompositeCacheManager cacheHub = CompositeCacheManager.getInstance();

  /** @see org.apache.velocity.servlet.VelocityServlet#handleRequest */
  protected Template handleRequest( HttpServletRequest request,
                                    HttpServletResponse response,
                                    Context context ) throws Exception
  {

    JCSAdminBean admin = new JCSAdminBean();

    String templateName = DEFAULT_TEMPLATE_NAME;

    // Get cacheName for actions from request (might be null)

    String cacheName = request.getParameter( CACHE_NAME_PARAM );

    // If an action was provided, handle it

    String action = request.getParameter( ACTION_PARAM );

    if ( action != null )
    {
      if ( action.equals( CLEAR_ALL_REGIONS_ACTION ) )
      {
        admin.clearAllRegions();
      }
      else if ( action.equals( CLEAR_REGION_ACTION ) )
      {
        if ( cacheName == null )
        {
          // Not Allowed
        }
        else
        {
          admin.clearRegion( cacheName );
        }
      }
      else if ( action.equals( REMOVE_ACTION ) )
      {
        String[] keys = request.getParameterValues( KEY_PARAM );

        for ( int i = 0; i < keys.length; i++ )
        {
          admin.removeItem( cacheName, keys[i] );
        }

        templateName = REGION_DETAIL_TEMPLATE_NAME;
      }
      else if ( action.equals( DETAIL_ACTION ) )
      {
        templateName = REGION_DETAIL_TEMPLATE_NAME;
      }
    }

    if ( request.getParameter( SILENT_PARAM ) != null )
    {
      // If silent parameter was passed, no output should be produced.

      return null;
    }
    // Populate the context based on the template

    if ( templateName == REGION_DETAIL_TEMPLATE_NAME )
    {
      context.put( "cacheName", cacheName );
      context.put( "elementInfoRecords", admin.buildElementInfo( cacheName ) );
    }
    else if ( templateName == DEFAULT_TEMPLATE_NAME )
    {
      context.put( "cacheInfoRecords", admin.buildCacheInfo() );
    }

    return getTemplate( templateName );
  }

}