我正在开发一个动态 Web 项目，尝试连接到数据库，目前正在尝试使用 JCS 加快速度。我将解释一切是如何走到这一步的。
我首先将二进制文件夹中的 commons-jcs3-core-3.0.jar 文件放在我的构建路径中，与 commons-logging-1.2.jar 一起，因为我相信它是一个依赖项。之后，我遵循了有关如何包含缓存的指南。我在我的 src 文件夹中放置了一个 cache.ccf 文件（实际上是通过从另一个项目中导入并编辑它），然后在 Servlet 类中添加导入。
这是我用于 cache.ccf 文件的代码，供参考：
# DEFAULT CACHE REGION
jcs.default=DC
jcs.default.cacheattributes=org.apache.commons.jcs.engine.CompositeCacheAttributes
jcs.default.cacheattributes.MaxObjects=1000
jcs.default.cacheattributes.MemoryCacheName=org.apache.commons.jcs.engine.memory.lru.LRUMemoryCache
jcs.default.cacheattributes.UseMemoryShrinker=false
jcs.default.cacheattributes.MaxMemoryIdleTime=3600
jcs.default.cacheattributes.ShrinkerInterval=60
jcs.default.elementattributes=org.apache.commons.jcs.engine.ElementAttributes
jcs.default.elementattributes.IsEternal=false
jcs.default.elementattributes.MaxLife=21600
jcs.default.elementattributes.IdleTime=1800
jcs.default.elementattributes.IsSpool=true
jcs.default.elementattributes.IsRemote=true
jcs.default.elementattributes.IsLateral=trues
之后，我添加了这一行：private CacheAccess<String, String> cache = null;
此单行导致发生此错误：
Jan 14, 2022 10:08:08 AM org.apache.catalina.core.ContainerBase startInternal
SEVERE: A child container failed during start
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Testing_Database_Connection]]
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:192)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:942)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:833)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1427)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1417)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Testing_Database_Connection]]
at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:440)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
... 6 more
Caused by: java.lang.NoClassDefFoundError: org/apache/commons/jcs3/access/exception/CacheException
at java.lang.Class.getDeclaredFields0(Native Method)
at java.lang.Class.privateGetDeclaredFields(Class.java:2583)
at java.lang.Class.getDeclaredFields(Class.java:1916)
at org.apache.catalina.util.Introspection.getDeclaredFields(Introspection.java:110)
at org.apache.catalina.startup.WebAnnotationSet.loadFieldsAnnotation(WebAnnotationSet.java:269)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:137)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:69)
at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:328)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:782)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5130)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
... 6 more
Caused by: java.lang.ClassNotFoundException: org.apache.commons.jcs3.access.exception.CacheException
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1415)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1223)
... 19 more
Jan 14, 2022 10:08:08 AM org.apache.catalina.core.ContainerBase startInternal
SEVERE: A child container failed during start
java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: A child container failed during start
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:192)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:942)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:263)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:763)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.startup.Catalina.start(Catalina.java:688)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:345)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:476)
Caused by: org.apache.catalina.LifecycleException: A child container failed during start
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:953)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:833)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1427)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1417)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Testing_Database_Connection]]
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:192)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:942)
... 8 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Testing_Database_Connection]]
at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:440)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
... 6 more
Caused by: java.lang.NoClassDefFoundError: org/apache/commons/jcs3/access/exception/CacheException
at java.lang.Class.getDeclaredFields0(Native Method)
at java.lang.Class.privateGetDeclaredFields(Class.java:2583)
at java.lang.Class.getDeclaredFields(Class.java:1916)
at org.apache.catalina.util.Introspection.getDeclaredFields(Introspection.java:110)
at org.apache.catalina.startup.WebAnnotationSet.loadFieldsAnnotation(WebAnnotationSet.java:269)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:137)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:69)
at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:328)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:782)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5130)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
... 6 more
Caused by: java.lang.ClassNotFoundException: org.apache.commons.jcs3.access.exception.CacheException
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1415)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1223)
... 19 more
Jan 14, 2022 10:08:08 AM org.apache.catalina.startup.Catalina start
SEVERE: The required Server component failed to start so Tomcat is unable to start.
org.apache.catalina.LifecycleException: A child container failed during start
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:953)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:263)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:421)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:763)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.startup.Catalina.start(Catalina.java:688)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:345)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:476)
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: A child container failed during start
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:192)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:942)
... 13 more
Caused by: org.apache.catalina.LifecycleException: A child container failed during start
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:953)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:833)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1427)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1417)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
Caused by: java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Testing_Database_Connection]]
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:192)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:942)
... 8 more
Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/Testing_Database_Connection]]
at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:440)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:198)
... 6 more
Caused by: java.lang.NoClassDefFoundError: org/apache/commons/jcs3/access/exception/CacheException
at java.lang.Class.getDeclaredFields0(Native Method)
at java.lang.Class.privateGetDeclaredFields(Class.java:2583)
at java.lang.Class.getDeclaredFields(Class.java:1916)
at org.apache.catalina.util.Introspection.getDeclaredFields(Introspection.java:110)
at org.apache.catalina.startup.WebAnnotationSet.loadFieldsAnnotation(WebAnnotationSet.java:269)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:137)
at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:69)
at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:328)
at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:782)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:299)
at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:123)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5130)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:183)
... 6 more
Caused by: java.lang.ClassNotFoundException: org.apache.commons.jcs3.access.exception.CacheException
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1415)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1223)
... 19 more
Jan 14, 2022 10:08:08 AM org.apache.coyote.AbstractProtocol pause
INFO: Pausing ProtocolHandler ["http-nio-8080"]
Jan 14, 2022 10:08:08 AM org.apache.catalina.core.StandardService stopInternal
INFO: Stopping service [Catalina]
Jan 14, 2022 10:08:08 AM org.apache.coyote.AbstractProtocol destroy
INFO: Destroying ProtocolHandler ["http-nio-8080"]
Picked up _JAVA_OPTIONS: -Djava.net.preferIPv4Stack=true
我已经看到参考资料表明这种错误是由 web.xml 中的拼写错误引起的，但我找不到任何重大错误：
<web-app>
<display-name>BeginnersBookDemo</display-name>
<servlet>
<servlet-name>HttpServletDemo</servlet-name>
<servlet-class>ServletDemo</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HttpServletDemo</servlet-name>
<url-pattern>/welcome</url-pattern>
</servlet-mapping>
</web-app>
那么，为什么包含 CacheAccess 会导致这个错误呢？例如，关于 JCS 的安装，我有什么可以解决的吗？