Java使用Memcached

这些天在设计SNA的架构，接触了一些远程缓存、集群、session复制等的东西，以前做企业应用的时候感觉作用不大，现在设计面对internet的系统架构时就非常有用了，而且在调试后看到压力测试的情况还是比较爽的。
4uV^M*b.W(d0在缓存的选择上有过很多的思考，虽然说memcached结合java在序列化上性能不怎么样，不过也没有更好的集群环境下的缓存解决方案了，就选择了memcached。本来计划等公司买的服务器到位装个linux再来研究memcached，但这两天在找到了一个windows下的Memcached版本，就动手开始调整现有的框架了。

windows下的Server端很简单，不用安装，双击运行后默认服务端口是11211，没有试着去更改端口，因为反正以后会用unix版本，到时再记录安装步骤。下载客户端的javaAPI包，接口非常简单，参考API手册上就有现成的例子。

目标，对旧框架缓存部分进行改造：

1、缓存工具类
2、hibernate的provider
3、用缓存实现session机制
今天先研究研究缓存工具类的改造，在旧框架中部分函数用了ehcache对执行结果进行了缓存处理，现在目标是提供一个缓存工具类，在配置文件中配置使用哪种缓存（memcached或ehcached），使其它程序对具体的缓存不依赖，同时使用AOP方式来对方法执行结果进行缓存。
首先是工具类的实现：
在Spring中配置
<!-- EhCache Manager --> <bean id="cacheManager" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean"> <property name="configLocation"> <value>classpath:ehcache.xml</value> </property> </bean> <bean id="localCache" class="org.springframework.cache.ehcache.EhCacheFactoryBean"> <property name="cacheManager" ref="cacheManager" /> <property name="cacheName" value="×××.cache.LOCAL_CACHE" /> </bean> <bean id="cacheService" class="×××.core.cache.CacheService" init-method="init" destroy-method="destory"> <property name="cacheServerList" value="${cache.servers}"/> <property name="cacheServerWeights" value="${cache.cacheServerWeights}"/> <property name="cacheCluster" value="${cache.cluster}"/> <property name="localCache" ref="localCache"/> </bean> <!-- EhCache Manager --> <bean id="cacheManager" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean"> <property name="configLocation"> <value>classpath:ehcache.xml</value> </property> </bean> <bean id="localCache" class="org.springframework.cache.ehcache.EhCacheFactoryBean"> <property name="cacheManager" ref="cacheManager" /> <property name="cacheName" value="×××.cache.LOCAL_CACHE" /> </bean> <bean id="cacheService" class="×××.core.cache.CacheService" init-method="init" destroy-method="destory"> <property name="cacheServerList" value="${cache.servers}"/> <property name="cacheServerWeights" value="${cache.cacheServerWeights}"/> <property name="cacheCluster" value="${cache.cluster}"/> <property name="localCache" ref="localCache"/> </bean>在properties文件中配置${cache.servers} ${cache.cacheServerWeights} ${cache.cluster}

Java 代码

/** * @author Marc * */ public class CacheService { private Log logger = LogFactory.getLog(getClass()); private Cache localCache; String cacheServerList; String cacheServerWeights; boolean cacheCluster = false; int initialConnections = 10; int minSpareConnections = 5; int maxSpareConnections = 50; long maxIdleTime = 1000 * 60 * 30; // 30 minutes long maxBusyTime = 1000 * 60 * 5; // 5 minutes long maintThreadSleep = 1000 * 5; // 5 seconds int socketTimeOut = 1000 * 3; // 3 seconds to block on reads int socketConnectTO = 1000 * 3; // 3 seconds to block on initial // connections. If 0, then will use blocking // connect (default) boolean failover = false; // turn off auto-failover in event of server // down boolean nagleAlg = false; // turn off Nagle's algorithm on all sockets in // pool MemCachedClient mc; public CacheService(){ mc = new MemCachedClient(); mc.setCompressEnable(false); } /** * 放入 * */ public void put(String key, Object obj) { Assert.hasText(key); Assert.notNull(obj); Assert.notNull(localCache); if (this.cacheCluster) { mc.set(key, obj); } else { Element element = new Element(key, (Serializable) obj); localCache.put(element); } } /** * 删除 */ public void remove(String key){ Assert.hasText(key); Assert.notNull(localCache); if (this.cacheCluster) { mc.delete(key); }else{ localCache.remove(key); } } /** * 得到 */ public Object get(String key) { Assert.hasText(key); Assert.notNull(localCache); Object rt = null; if (this.cacheCluster) { rt = mc.get(key); } else { Element element = null; try { element = localCache.get(key); } catch (CacheException cacheException) { throw new DataRetrievalFailureException("Cache failure: " + cacheException.getMessage()); } if(element != null) rt = element.getValue(); } return rt; } /** * 判断是否存在 * */ public boolean exist(String key){ Assert.hasText(key); Assert.notNull(localCache); if (this.cacheCluster) { return mc.keyExists(key); }else{ return this.localCache.isKeyInCache(key); } } private void init() { if (this.cacheCluster) { String[] serverlist = cacheServerList.split(","); Integer[] weights = this.split(cacheServerWeights); // initialize the pool for memcache servers SockIOPool pool = SockIOPool.getInstance(); pool.setServers(serverlist); pool.setWeights(weights); pool.setInitConn(initialConnections); pool.setMinConn(minSpareConnections); pool.setMaxConn(maxSpareConnections); pool.setMaxIdle(maxIdleTime); pool.setMaxBusyTime(maxBusyTime); pool.setMaintSleep(maintThreadSleep); pool.setSocketTO(socketTimeOut); pool.setSocketConnectTO(socketConnectTO); pool.setNagle(nagleAlg); pool.setHashingAlg(SockIOPool.NEW_COMPAT_HASH); pool.initialize(); logger.info("初始化memcached pool!"); } } private void destory() { if (this.cacheCluster) { SockIOPool.getInstance().shutDown(); } } }

AOP拦截类

public class CachingInterceptor implements MethodInterceptor { private CacheService cacheService; private String cacheKey; public void setCacheKey(String cacheKey) { this.cacheKey = cacheKey; } public void setCacheService(CacheService cacheService) { this.cacheService = cacheService; } public Object invoke(MethodInvocation invocation) throws Throwable { Object result = cacheService.get(cacheKey); //如果函数返回结果不在Cache中,执行函数并将结果放入Cache if (result == null) { result = invocation.proceed(); cacheService.put(cacheKey,result); } return result; } } public class CachingInterceptor implements MethodInterceptor { private CacheService cacheService; private String cacheKey; public void setCacheKey(String cacheKey) { this.cacheKey = cacheKey; } public void setCacheService(CacheService cacheService) { this.cacheService = cacheService; } public Object invoke(MethodInvocation invocation) throws Throwable { Object result = cacheService.get(cacheKey); //如果函数返回结果不在Cache中,执行函数并将结果放入Cache if (result == null) { result = invocation.proceed(); cacheService.put(cacheKey,result); } return result; } }

Spring的AOP配置如下： 

<aop:config proxy-target-class="true"> <aop:advisor pointcut="execution(* ×××.PoiService.getOne(..))" advice-ref="PoiServiceCachingAdvice" /> </aop:config> <bean id="BasPoiServiceCachingAdvice" class="×××.core.cache.CachingInterceptor"> <property name="cacheKey" value="PoiService" /> <property name="cacheService" ref="cacheService" /> </bean>

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