Question

我正在运行一个struts2应用程序，我必须实现一个缓存来缓存某些响应。我已经使用了EHCache并创建了一个帮助器类来初始化和配置缓存，如下所示：

import java.io.File;

import org.ehcache.Cache;
import org.ehcache.CacheManager;
import org.ehcache.PersistentCacheManager;
import org.ehcache.config.builders.CacheConfigurationBuilder;
import org.ehcache.config.builders.CacheManagerBuilder;
import org.ehcache.config.builders.ResourcePoolsBuilder;
import org.ehcache.config.units.MemoryUnit;

import gate.util.Pair;
import net.ha.apserver.util.LoggerManager;

public class HACacheManager {
    private PersistentCacheManager pCacheManager;
    private Cache<String, Object> patientCache;

    public HACacheManager() {
        pCacheManager = CacheManagerBuilder
                            .newCacheManagerBuilder()
                            .with(CacheManagerBuilder
                                    .persistence(System.getProperty("java.io.tempdir")+File.separator+"haCache")).build();
        pCacheManager.init();
        pCacheManager.createCache("patientList-cache", CacheConfigurationBuilder
                                    .newCacheConfigurationBuilder(
                                            String.class, 
                                            Pair.class, 
                                            ResourcePoolsBuilder.heap(10).disk(100, MemoryUnit.MB, true)));
    }

    public CacheManager getHACacheManager() {
        return pCacheManager;
    }

    public Cache<String,Pair> getPatientCache() {
        return pCacheManager.getCache("patientList-cache", String.class, Pair.class);
    }
}

然后，我在代码库的其他地方使用了以下缓存：

// Check cache for existing data first
        HACacheManager cacheManager = new HACacheManager();
        Cache<String, Pair> patientCache = cacheManager.getPatientCache();
        String key = organizationId+","+startCount+","+recordCount; // Key based on method arguments
        if(patientCache.containsKey(key)) {
            return (Pair) patientCache.get(key);
        }

，然后如果在缓存中找不到密钥，那么我们在缓存中创建一个新元素：

    Pair returnPair = new Pair(patientCount, patientList); 
    patientCache.put(key, returnPair);

现在，我第一次在浏览器的struts2中调用该操作时，它将正确显示JSP，并且正确显示了我返回的值，这意味着它们也已在缓存中设置。

但是，如果我第二次调用同一操作，则会收到以下异常：

org.ehcache.StateTransitionException: Persistence directory already locked by another process: D:\tools\eclipse-oxygen\eclipse\null\haCache
org.ehcache.core.StatusTransitioner$Transition.failed(StatusTransitioner.java:235)
org.ehcache.core.EhcacheManager.init(EhcacheManager.java:603)
net.ha.apserver.controller.HACacheManager.(HACacheManager.java:26)
net.ha.apserver.controller.UserManager.getUserPatients(UserManager.java:472)
net.ha.apserver.view.CohortSearchAction.getPatient(CohortSearchAction.java:853)
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Unknown Source)
com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:441)
com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:280)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:243)
com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:165)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:252)
org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:68)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:122)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:195)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:179)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:75)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:94)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:235)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:89)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:130)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:267)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:126)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:138)
com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:87)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:165)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:179)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:176)
com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:237)
org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:52)
org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:488)
org.apache.struts2.dispatcher.FilterDispatcher.doFilter(FilterDispatcher.java:395)
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
org.apache.catalina.filters.CorsFilter.handleNonCORS(CorsFilter.java:352)
org.apache.catalina.filters.CorsFilter.doFilter(CorsFilter.java:171)
org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:199)
org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)
org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668)
org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:791)
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417)
org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Unknown Source)

在这一点上，我别无选择，只能重新启动服务器，因为随后的调用会给出相同的异常。我错过了一些配置吗？

Answer 1

您已在您的方法中初始化 HACacheManager，即由操作调用。每次点击操作时，都会初始化 cacheManager。 Ehcache 不允许两次创建具有相同路径的缓存。通过创建静态引用并在您的操作/方法中使用该引用来初始化一次。

public static HACacheManager cacheManager = new HACacheManager();

或者更好地创建一个单例实例。在您的 HACacheManager 类中添加以下几行：

private static HACacheManager cacheManager = null;
public static HACacheManager getInstance() { 
    if (cacheManager == null) 
        cacheManager = new HACacheManager();
    return cacheManager; 
}

并从您的操作/方法中调用以下方法：

HACacheManager cacheManager = HACacheManager.getInstance();

EHCache-org.ehcache.StateTransitionException：持久性目录已被另一个进程锁定

1 个答案: