我正在尝试使用RMI实现EhCache复制缓存。我有一个使用EhCache进行数据缓存的Spring Web应用程序。 Ehcache拥有很少的Java.Util.Map，用于整个应用程序视图页面。当用户从前端屏幕创建记录（比如一些商业JAVA POJO对象）时，该记录将被插入到数据库中，随后，EhCache保存的地图将被更新。
稍后，我们在同一台机器中的 3个tomcat实例中部署了此Web应用程序。可以通过Apache HTTP Load Balancer访问应用程序。
Promblem我面临的是，EhCache数据正在一个tomcat实例上加载。但不是其他两个。当使用端口号单独访问应用程序时，应用程序运行正常。
相同的Spring Web应用程序在Tomcat实例（9001,9002,9003）上运行。 EhCache RMI配置为侦听（4001,4002,4003）。
请找到我配置的ehCache.xml文件
在Tomcat实例1上
<?xml version="1.0" encoding="UTF-8"?>
<ehcache name="WidgetCache" updateCheck="false">
<defaultCache maxElementsInMemory="10000" eternal="false"
timeToIdleSeconds="0" timeToLiveSeconds="0" overflowToDisk="true"
diskPersistent="false" diskExpiryThreadIntervalSeconds="120"
memoryStoreEvictionPolicy="LRU" />
<cacheManagerPeerListenerFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerListenerFactory"
properties="hostName=10.237.31.33, port=40001, socketTimeoutMillis=2000" />
<cacheManagerPeerProviderFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerProviderFactory"
properties="peerDiscovery=manual,
rmiUrls=//10.237.31.33:40002/widgets|//10.237.31.33:40002/lobCache|//10.237.31.33:40002/lobFilterCache|//10.237.31.33:40002/glossarylobFilterCache|//10.237.31.33:40002/bbpUserListCache|//10.237.31.33:40002/userRoleCache|//10.237.31.33:40002/glossary|//10.237.31.33:40003/widgets|//10.237.31.33:40003/lobCache|//10.237.31.33:40003/lobFilterCache|//10.237.31.33:40003/glossarylobFilterCache|//10.237.31.33:40003/bbpUserListCache|//10.237.31.33:40003/userRoleCache|//10.237.31.33:40003/glossary" />
<cache name="userRoleCache" maxElementsInMemory="100" eternal="false"
timeToIdleSeconds="0" timeToLiveSeconds="0" memoryStoreEvictionPolicy="LFU">
<cacheEventListenerFactory
class="net.sf.ehcache.distribution.RMICacheReplicatorFactory"
properties="replicateAsynchronously=true, replicatePuts=true, replicateUpdates=true,replicateUpdatesViaCopy=false, replicateRemovals=true" />
</cache>
<diskStore path="java.io.tmpdir" />
在Tomcat实例2上
<?xml version="1.0" encoding="UTF-8"?>
<ehcache name="WidgetCache" updateCheck="false">
<defaultCache maxElementsInMemory="10000" eternal="false"
timeToIdleSeconds="0" timeToLiveSeconds="0" overflowToDisk="true"
diskPersistent="false" diskExpiryThreadIntervalSeconds="120"
memoryStoreEvictionPolicy="LRU" />
<cacheManagerPeerListenerFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerListenerFactory"
properties="hostName=10.237.31.33, port=40002, socketTimeoutMillis=2000" />
<cacheManagerPeerProviderFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerProviderFactory"
properties="peerDiscovery=manual,
rmiUrls=//10.237.31.33:40001/widgets|//10.237.31.33:40001/lobCache|//10.237.31.33:40001/lobFilterCache|//10.237.31.33:40001/glossarylobFilterCache|//10.237.31.33:40001/bbpUserListCache|//10.237.31.33:40001/userRoleCache|//10.237.31.33:40001/glossary|//10.237.31.33:40003/widgets|//10.237.31.33:40003/lobCache|//10.237.31.33:40003/lobFilterCache|//10.237.31.33:40003/glossarylobFilterCache|//10.237.31.33:40003/bbpUserListCache|//10.237.31.33:40003/userRoleCache|//10.237.31.33:40003/glossary" />
<cache name="userRoleCache" maxElementsInMemory="100" eternal="false"
timeToIdleSeconds="0" timeToLiveSeconds="0" memoryStoreEvictionPolicy="LFU">
<cacheEventListenerFactory
class="net.sf.ehcache.distribution.RMICacheReplicatorFactory"
properties="replicateAsynchronously=true, replicatePuts=true, replicateUpdates=true,replicateUpdatesViaCopy=false, replicateRemovals=true" />
</cache>
<diskStore path="java.io.tmpdir" />
在Tomcat实例3上
<?xml version="1.0" encoding="UTF-8"?>
<ehcache name="WidgetCache" updateCheck="false">
<defaultCache maxElementsInMemory="10000" eternal="false"
timeToIdleSeconds="0" timeToLiveSeconds="0" overflowToDisk="true"
diskPersistent="false" diskExpiryThreadIntervalSeconds="120"
memoryStoreEvictionPolicy="LRU" />
<cacheManagerPeerListenerFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerListenerFactory"
properties="hostName=10.237.31.33, port=40003, socketTimeoutMillis=2000" />
<cacheManagerPeerProviderFactory
class="net.sf.ehcache.distribution.RMICacheManagerPeerProviderFactory"
properties="peerDiscovery=manual,
rmiUrls=//10.237.31.33:40001/widgets|//10.237.31.33:40001/lobCache|//10.237.31.33:40001/lobFilterCache|//10.237.31.33:40001/glossarylobFilterCache|//10.237.31.33:40001/bbpUserListCache|//10.237.31.33:40001/userRoleCache|//10.237.31.33:40001/glossary|//10.237.31.33:40002/widgets|//10.237.31.33:40002/lobCache|//10.237.31.33:40002/lobFilterCache|//10.237.31.33:40002/glossarylobFilterCache|//10.237.31.33:40002/bbpUserListCache|//10.237.31.33:40002/userRoleCache|//10.237.31.33:40002/glossary" />
<cache name="userRoleCache" maxElementsInMemory="100" eternal="false"
timeToIdleSeconds="0" timeToLiveSeconds="0" memoryStoreEvictionPolicy="LFU">
<cacheEventListenerFactory
class="net.sf.ehcache.distribution.RMICacheReplicatorFactory"
properties="replicateAsynchronously=true, replicatePuts=true, replicateUpdates=true,replicateUpdatesViaCopy=false, replicateRemovals=true" />
</cache>
<diskStore path="java.io.tmpdir" />
请告知我在这里缺少的东西。
以下是在spring-servlet.xml中配置的
<bean id="cacheManager" class="org.springframework.cache.ehcache.EhCacheCacheManager" p:cache-manager-ref="ehcache" />
<bean id="ehcache" class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean"
p:config-location="classpath:ehcache.xml" p:shared="true"/>
来自Java业务类
public class PortfolioUserDetailsServiceImpl implements PortfolioUserDetailsService {
private Logger logger = LoggerFactory
.getLogger(PortfolioUserDetailsServiceImpl.class);
private UserDao userDao;
@Autowired
private CacheManager cacheManager;
private Ehcache userRoleCache;
@PostConstruct
public void init() {
// Load our widgets cache:
userRoleCache = cacheManager.getEhcache("userRoleCache");
// Create an EHCache Element to hold the widget
Element element = new Element("getAllRoles", userDao.getAllRoles());
// Add the element to the cache
userRoleCache.put(element);
}
我在以下方法上得到NullPointerException
@Override
public List<BbpUser> loadUsersfromUserListCache() throws InventoryException {
// TODO Auto-generated method stub
Cache cache = cacheManager.getCache("userRoleCache");
Element elementt = cache.get("getAllRoles");
return (List<BbpUser>) elementt.getObjectValue();
}
答案 0 :(得分：0)
当replicateUpdatesViaCopy设置为false时，将从其他实例上的缓存中删除条目。您需要检查null并从数据存储区加载它（或者您拥有最新值时）。
您可以将replicateUpdatesViaCopy设置为true，并检查您是否仍在访问其他实例时获取NPE。