com.googlecode.ehcache.annotations.support.TaskSchedulerAdapterFactory Maven / Gradle / Ivy

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Provides a simple model for integrating Ehcache in a Spring project via annotations.
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/**
 * Copyright 2010-2011 Nicholas Blair, Eric Dalquist
 *
 * 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.
 */
package com.googlecode.ehcache.annotations.support;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.Timer;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.util.Assert;


/**
 * Utility for dealing with the 'fun' of supporting a class that only exists in Spring 3.0. Uses reflection to
 * determine if TaskScheduler is available and wraps it to the project-specific task scheduler api. Also supports
 * Timer use.
 * 
 * @author Eric Dalquist
 * @version $Revision: 671 $
 */
public final class TaskSchedulerAdapterFactory {
    private static final Logger LOGGER = LoggerFactory.getLogger(TaskSchedulerAdapterFactory.class);
    
    private final static Class TASK_SCHEDULER_CLASS ;
    private final static Class SPRING3_TASK_SCHEDULER_ADAPTOR_CLASS ;
    private final static Constructor SPRING3_TASK_SCHEDULER_ADAPTOR_CONSTRUCTOR ;
    private final static boolean SPRING3;
    
    static {
        //Use local variables so that the static class variables can be final
        Class taskSchedulerClass = null;
        Class spring3TaskSchedulerAdaptorClass = null;
        Constructor spring3TaskSchedulerAdpatorConstructor = null;
        try {
            taskSchedulerClass = Class.forName("org.springframework.scheduling.TaskScheduler");
            spring3TaskSchedulerAdaptorClass = Class.forName("com.googlecode.ehcache.annotations.support.Spring3TaskSchedulerAdapter");
            spring3TaskSchedulerAdpatorConstructor = spring3TaskSchedulerAdaptorClass.getConstructor(taskSchedulerClass);
            
            LOGGER.debug("Found Spring 3.0 TaskScheduler, will use Spring3TaskSchedulerAdapter if provided with a TaskScheduler");
        }
        catch (Exception e) {
            //Ignore, assume we're not running in Spring 3.0
            LOGGER.debug("Could not find Spring 3.0 TaskScheduler, will use TimerTaskSchedulerAdapter if provided with a Timer");
        }
        
        //init static class variables
        TASK_SCHEDULER_CLASS = taskSchedulerClass;
        SPRING3_TASK_SCHEDULER_ADAPTOR_CLASS = spring3TaskSchedulerAdaptorClass;
        SPRING3_TASK_SCHEDULER_ADAPTOR_CONSTRUCTOR = spring3TaskSchedulerAdpatorConstructor;
        
        SPRING3 = TASK_SCHEDULER_CLASS != null && 
            SPRING3_TASK_SCHEDULER_ADAPTOR_CLASS != null && 
            SPRING3_TASK_SCHEDULER_ADAPTOR_CONSTRUCTOR != null;
    }
    
    public static TaskSchedulerAdapter createTaskSchedulerAdapter(Object scheduler) {
        Assert.notNull(scheduler);
        
        //See if the scheduler implements our adapter interface directly, if so just return it
        if (scheduler instanceof TaskSchedulerAdapter) {
            return (TaskSchedulerAdapter)scheduler;
        }
        
        //Check if a Spring 3 TaskScheduler was provided and wrap it
        if (SPRING3 && TASK_SCHEDULER_CLASS.isAssignableFrom(scheduler.getClass())) {
            try {
                return (TaskSchedulerAdapter)SPRING3_TASK_SCHEDULER_ADAPTOR_CONSTRUCTOR.newInstance(scheduler);
            }
            catch (InstantiationException e) {
                throw new IllegalStateException("Failed to create Spring3TaskSchedulerAdapter instance by reflection to wrap " + scheduler.getClass(), e);
            }
            catch (IllegalAccessException e) {
                throw new IllegalStateException("Failed to create Spring3TaskSchedulerAdapter instance by reflection to wrap " + scheduler.getClass(), e);
            }
            catch (InvocationTargetException e) {
                throw new IllegalStateException("Failed to create Spring3TaskSchedulerAdapter instance by reflection to wrap " + scheduler.getClass(), e);
            }
        }
        
        //Check if a Timer was provided
        if (scheduler instanceof Timer) {
            return new TimerTaskSchedulerAdapter((Timer)scheduler);
        }
        
        throw new IllegalArgumentException("Provided scheduler object of type " + scheduler.getClass() + " is not supported. Please provide a TaskScheduler, Timer or TaskSchedulerAdapter");
    }
    
    private TaskSchedulerAdapterFactory() {}
}