利用Spring AOP 缓存方法结果集(上)

我们都知道Hibernate可以用ehcache来作为Second Level Cache.主要是针对POJO的缓存,而且缓存的读取

在Hibernate中是写死.实际运用中感觉很不灵活.今天看到一篇介绍利用Spring Interceptor 来缓存指定

方法结果的例子,感觉很不错,充分体会到AOP的强大力量 :)

首先配置ehcache.xml

 <ehcache>

 

    <diskStore path="java.io.tmpdir"/>

<defaultCache name="default"

        maxElementsInMemory="300"

        eternal="false"

        timeToIdleSeconds="500"

        timeToLiveSeconds="500"

        overflowToDisk="true"
       
        diskPersistent="false"
       
        diskExpiryThreadIntervalSeconds="110"

        />

    <cache name="org.taha.cache.METHOD_CACHE"

        maxElementsInMemory="300"

        eternal="false"

        timeToIdleSeconds="500"

        timeToLiveSeconds="500"

        overflowToDisk="true"

        />

</ehcache>

 

接下在Spring配置文件中定义Ehcache组件

 

<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>

建立我们自己的方法拦截器MethodCacheInterceptor.

MethodCacheInterceptor实现了org.aopalliance.intercept.MethodInterceptor接口.

import java.io.Serializable;

 

import net.sf.ehcache.Cache;

import net.sf.ehcache.Element;

 

import org.aopalliance.intercept.MethodInterceptor;

import org.aopalliance.intercept.MethodInvocation;

import org.springframework.beans.factory.InitializingBean;

 

/**

 * 拦截器,用于缓存方法返回结果.

 *

 * @version $Id: MethodCacheInterceptor.java v 1.0 2004-11-28 14:57:00 Znjq Exp $

 * @author <a href="mailto:[e-mail]">Znjq </a>

 */

public class MethodCacheInterceptor implements MethodInterceptor,

        InitializingBean {

    private Cache cache;

 

    /**

     * sets cache name to be used

     */

    public void setCache(Cache cache) {

        this.cache = cache;

    }

 

    /*

     * (non-Javadoc)

     *

     * @see org.aopalliance.intercept.MethodInterceptor#invoke(org.aopalliance.intercept.MethodInvocation)

     */

    public Object invoke(MethodInvocation invocation) throws Throwable {

       String targetName = invocation.getThis().getClass().getName();

        String methodName = invocation.getMethod().getName();

        Object[] arguments = invocation.getArguments();

        Object result;

 

        String cacheKey = getCacheKey(targetName, methodName, arguments);

        Element element = cache.get(cacheKey);

        if (element == null) {

            //call target/sub-interceptor

            result = invocation.proceed();

 

            //cache method 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();

    }

 

    /*

     * (non-Javadoc)

     *

     * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet()

     */

    public void afterPropertiesSet() throws Exception {

        // TODO Auto-generated method stub

 

    }

}