src/java/org/apache/velocity/runtime/log/AvalonLogSystem.java

package org.apache.velocity.runtime.log;

/*
 * 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 java.io.File;

import org.apache.log.Priority;
import org.apache.log.Logger;
import org.apache.log.Hierarchy;
import org.apache.log.LogTarget;
import org.apache.log.output.io.FileTarget;

import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.runtime.RuntimeConstants;

/**
 * Implementation of a Avalon logger.
 *
 * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a>
 * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
 * @version $Id$
 */
public class AvalonLogSystem implements LogSystem
{
    private Logger logger = null;

    private RuntimeServices rsvc = null;

    /**
     *  default CTOR.  Initializes itself using the property RUNTIME_LOG
     *  from the Velocity properties
     */

    public AvalonLogSystem()
    {
    }

    public void init( RuntimeServices rs )
        throws Exception
    {
        this.rsvc = rs;

        /*
         *  if a logger is specified, we will use this instead of
         *  the default
         */
        String loggerName = (String) rsvc.getProperty("runtime.log.logsystem.avalon.logger");
        
        if (loggerName != null)
        {
            this.logger = Hierarchy.getDefaultHierarchy().getLoggerFor(loggerName);
        } 
        else 
        {
            /*
             *  since this is a Velocity-provided logger, we will
             *  use the Runtime configuration
             */
            String logfile = (String) rsvc.getProperty( RuntimeConstants.RUNTIME_LOG );

            /*
             *  now init.  If we can't, panic!
             */
            try
            {
                init( logfile );

                logVelocityMessage( 0,
                    "AvalonLogSystem initialized using logfile '" + logfile + "'" );
            }
            catch( Exception e )
            {
                System.err.println(
                    "PANIC : Error configuring AvalonLogSystem : " + e );

                throw new Exception("Unable to configure AvalonLogSystem : " + e );
            }
        }
    }

    /**
     *  initializes the log system using the logfile argument
     *
     *  @param logFile   file for log messages
     */
    public void init(String logFile)
        throws Exception
    {

	/*
	 *  make our FileTarget.  Note we are going to keep the 
	 *  default behavior of not appending...
	 */
        FileTarget target = new FileTarget( new File( logFile), 
					    false, 
					    new VelocityFormatter("%{time} %{message}\\n%{throwable}" ) );
       
        /*
         *  use the toString() of RuntimeServices to make a unique logger
         */

        logger = Hierarchy.getDefaultHierarchy().getLoggerFor( rsvc.toString() );
        logger.setPriority( Priority.DEBUG );
        logger.setLogTargets( new LogTarget[] { target } );
    }
    
    /**
     *  logs messages
     *
     *  @param level severity level
     *  @param message complete error message
     */
    public void logVelocityMessage(int level, String message)
    {
        /*
         *  based on level, call teh right logger method
         *  and prefix with the appropos prefix
         */

        switch (level) 
        {
            case LogSystem.WARN_ID:
                logger.warn( RuntimeConstants.WARN_PREFIX + message );
                break;
            case LogSystem.INFO_ID:
                logger.info( RuntimeConstants.INFO_PREFIX + message);
                break;
            case LogSystem.DEBUG_ID:
                logger.debug( RuntimeConstants.DEBUG_PREFIX + message);
                break;
            case LogSystem.ERROR_ID:
                logger.error(RuntimeConstants.ERROR_PREFIX + message);
                break;
            default:
                logger.info( message);
                break;
        }
    }
}