<ehcache>

    <!-- Sets the path to the directory where cache .data files are created.

         If the path is a Java System Property it is replaced by
         its value in the running VM.

         The following properties are translated:
         user.home - User's home directory
         user.dir - User's current working directory
         java.io.tmpdir - Default temp file path -->
    <diskStore path="java.io.tmpdir"/>


    <!--Default Cache configuration. These will applied to caches programmatically created through
        the CacheManager.

        The following attributes are required for defaultCache:

        maxInMemory       - Sets the maximum number of objects that will be created in memory
        eternal           - Sets whether elements are eternal. If eternal,  timeouts are ignored and 
                            the element is never expired.
        timeToIdleSeconds - Sets the time to idle for an element before it expires.
                            i.e. The maximum amount of time between accesses before an element expires
                            Is only used if the element is not eternal.
                            Optional attribute. A value of 0 means that an Element can idle for infinity
        timeToLiveSeconds - Sets the time to live for an element before it expires.
                            i.e. The maximum time between creation time and when an element expires.
                            Is only used if the element is not eternal.
        overflowToDisk    - Sets whether elements can overflow to disk when the in-memory cache
                            has reached the maxInMemory limit.

        -->

    <cache name="org.taha.cache.METHOD_CACHE"
        maxElementsInMemory="300"
        eternal="false"
        timeToIdleSeconds="500"
        timeToLiveSeconds="500"
        overflowToDisk="true"
        />
</ehcache>

<!-- ==============================   CACHE   ============================= -->

<bean id="cacheManager" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean">
  <property name="configLocation">
    <value>classpath:ehcache.xml</value>
  </property>
</bean>

<bean id="methodCache" class="org.springframework.cache.ehcache.EhCacheFactoryBean">
  <property name="cacheManager">
    <ref local="cacheManager"/>
  </property>
  <property name="cacheName">
    <value>org.taha.cache.METHOD_CACHE</value>
  </property>
</bean>

/*
 * Copyright 2002-2004 the original author or authors.
 *
 * 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 org.taha.interceptor;

import java.io.Serializable;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.Log;

import org.springframework.beans.factory.InitializingBean;
import org.springframework.util.Assert;

import net.sf.ehcache.Cache;
import net.sf.ehcache.Element;

/**
 * @author <a href="mailto:[email protected]">Omar Irbouh</a>
 * @since 2004.10.07
 */
public class MethodCacheInterceptor implements MethodInterceptor, InitializingBean {
  private static final Log logger = LogFactory.getLog(MethodCacheInterceptor.class);

  private Cache cache;

  /**
   * sets cache name to be used
   */
  public void setCache(Cache cache) {
    this.cache = cache;
  }

  /**
   * Checks if required attributes are provided.
   */
  public void afterPropertiesSet() throws Exception {
    Assert.notNull(cache, "A cache is required. Use setCache(Cache) to provide one.");
  }

  /**
   * main method
   * caches method result if method is configured for caching
   * method results must be serializable
   */
  public Object invoke(MethodInvocation invocation) throws Throwable {
    String targetName  = invocation.getThis().getClass().getName();
    String methodName  = invocation.getMethod().getName();
    Object[] arguments = invocation.getArguments();
    Object result;

    logger.debug("looking for method result in cache");
    String cacheKey = getCacheKey(targetName, methodName, arguments);
    Element element = cache.get(cacheKey);
    if (element == null) {
      //call target/sub-interceptor       logger.debug("calling intercepted method");
      result = invocation.proceed();

      //cache method result       logger.debug("caching result");
      element = new Element(cacheKey, (Serializable) result);
      cache.put(element);
    }
    return element.getValue();
  }

  /**
   * creates cache key: targetName.methodName.argument0.argument1...
   */
  private String getCacheKey(String targetName,
                             String methodName,
                             Object[] arguments) {
    StringBuffer sb = new StringBuffer();
    sb.append(targetName)
      .append(".").append(methodName);
    if ((arguments != null) && (arguments.length != 0)) {
      for (int i=0; i<arguments.length; i++) {
        sb.append(".")
          .append(arguments[i]);
      }
    }

    return sb.toString();
  }
}

<bean id="methodCacheInterceptor" class="org.taha.interceptor.MethodCacheInterceptor">
  <property name="cache">
    <ref local="methodCache" />
  </property>
</bean>

<bean id="methodCachePointCut" class="org.springframework.aop.support.RegexpMethodPointcutAdvisor">
  <property name="advice">
    <ref local="methodCacheInterceptor"/>
  </property>
  <property name="patterns">
    <list>
      <value>.*methodOne</value>
      <value>.*methodTwo</value>
    </list>
  </property>
</bean>

<bean id="myBean" class="org.springframework.aop.framework.ProxyFactoryBean">
  <property name="target">
   <bean class="org.taha.beans.MyBean"/>
  </property>
  <property name="interceptorNames">
    <list>
      <value>methodCachePointCut</value>
    </list>
  </property>
</bean>