以下堆栈跟踪是我尝试访问一个 servlet 时得到的，它似乎在 Tomcat 管理器中运行良好。
11 Sep, 2012 11:50:12 AM org.apache.catalina.core.ApplicationContext log
INFO: Marking servlet LoginServlet as unavailable
11 Sep, 2012 11:50:12 AM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Allocate exception for servlet LoginServlet
java.lang.Error: Unresolved compilation problems:
The import javax.servlet cannot be resolved
The import javax.servlet cannot be resolved
The import javax.servlet cannot be resolved
The import javax.servlet cannot be resolved
The import javax.servlet cannot be resolved
The import javax.servlet cannot be resolved
HttpServlet cannot be resolved to a type
ServletConfig cannot be resolved to a type
ServletException cannot be resolved to a type
HttpServlet cannot be resolved to a type
ServletContext cannot be resolved to a type
ServletException cannot be resolved to a type
HttpServletRequest cannot be resolved to a type
HttpServletResponse cannot be resolved to a type
ServletException cannot be resolved to a type
request cannot be resolved
The method getLoggedin() from the type LoginHandler refers to the missing type ServletException
The method destroy() of type LoginManager must override or implement a supertype method
HttpServlet cannot be resolved to a type
at com.login.servlets.LoginManager.<init>(LoginManager.java:5)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1149)
at org.apache.catalina.core.StandardWrapper.allocate(StandardWrapper.java:827)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:129)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:877)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:594)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1675)
at java.lang.Thread.run(Unknown Source)
11 Sep, 2012 12:05:12 PM org.apache.catalina.core.ApplicationContext log
INFO: Marking servlet Log4JInitServlet as unavailable
11 Sep, 2012 12:05:12 PM org.apache.catalina.core.StandardContext loadOnStartup
SEVERE: Servlet /logintest threw load() exception
java.lang.Error: Unresolved compilation problems:
The import javax.servlet cannot be resolved
The import javax.servlet cannot be resolved
The import javax.servlet cannot be resolved
The import javax.servlet cannot be resolved
The import org.apache cannot be resolved
The import org.apache cannot be resolved
HttpServlet cannot be resolved to a type
ServletConfig cannot be resolved to a type
ServletException cannot be resolved to a type
ServletContext cannot be resolved to a type
BasicConfigurator cannot be resolved
PropertyConfigurator cannot be resolved
BasicConfigurator cannot be resolved
at com.logger.WebLogger.<init>(WebLogger.java:5)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at org.apache.catalina.core.StandardWrapper.loadServlet(StandardWrapper.java:1149)
at org.apache.catalina.core.StandardWrapper.load(StandardWrapper.java:1026)
at org.apache.catalina.core.StandardContext.loadOnStartup(StandardContext.java:4421)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4734)
at org.apache.catalina.core.StandardContext.reload(StandardContext.java:3461)
at org.apache.catalina.manager.ManagerServlet.reload(ManagerServlet.java:943)
at org.apache.catalina.manager.HTMLManagerServlet.reload(HTMLManagerServlet.java:557)
at org.apache.catalina.manager.HTMLManagerServlet.doGet(HTMLManagerServlet.java:121)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.filters.CsrfPreventionFilter.doFilter(CsrfPreventionFilter.java:186)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:563)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:293)
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:877)
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:594)
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1675)
at java.lang.Thread.run(Unknown Source)
在 eclipse 类路径中使用的所有 jar 都可以在 Tomcat lib 文件夹中找到。 webapp 正在部署时没有任何错误日志，但是当我尝试访问一个 servlet 时，会发生此异常，并且我将其记录在 tomcat 日志中。有人可以帮忙吗？
The package names are proper inside 'classes', also, the web.xml is proper.
我不知道为什么会这样。还有一些其他的网络应用程序，它们几乎使用相同的库运行良好。期待有人能帮我解决这个问题..
谢谢
最佳答案
终于明白我的错误了。这是由 eclipse 构建引起的问题。由于构建不正确，类文件已损坏。我清理了整个项目，重新构建，现在工作正常。感谢您的回复。
关于java - 小服务程序 : SEVERE: Allocate exception for servlet，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/12366201/