Java环境下Memcached应用详解

转自：http://developer.51cto.com  2009-09-17 10:59  yxq375  ITPUB 

这里将介绍Java环境下Memcached应用，Memcached主要是集群环境下的缓存解决方案，希望本文对大家有所帮助。
本文将对在Java环境下Memcached应用进行详细介绍。Memcached主要是集群环境下的缓存解决方案，可以运行在Java或者.NET平台上，这里我们主要讲的是Windows下的Memcached应用。

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好的。

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
Java代码


     <bean id="cacheManager"    class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean">     <property name="configLocation">     <value>classpath:ehcache.xmlvalue>     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="${cache.cluster}"/>     <property name="localCache" ref="localCache"/>     bean>     <bean id="cacheManager" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean"> <property name="configLocation"> <value>classpath:ehcache.xmlvalue> property> bean> <bean id="localCache" class="org.springframework.cache.ehcache.EhCacheFactoryBean"> <property name="cacheManager" ref="cacheManager" /> <property name="cacheName" value="×××.cache.LOCAL_CACHE" /> bean>  <bean id="cacheService" class="×××.core.cache.CacheService" init-method="init" destroy-method="destory"> <property name="cacheServerList" value="${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}

具体工具类的代码

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();     }     }     }    /**  * @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memcachedpool!");  }  }  private void destory() {  if (this.cacheCluster) {  SockIOPool.getInstance().shutDown();  }  }  }  然后实现函数的AOP拦截类，用来在函数执行前返回缓存内容

Java代码


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：

Java代码

<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>