运行eclipse动态web小程序保存，用etmvc

Question

严重: Servlet.service() for servlet [default] in context with path [/myDemo] threw exception [java.lang.reflect.InvocationTargetException] with root cause
java.lang.NullPointerException
at com.et.ar.ConnectionHolder.(ConnectionHolder.java:26)
at com.et.ar.ActiveRecordBase.findBySql(ActiveRecordBase.java:609)
at com.et.ar.ActiveRecordBase.findAll(ActiveRecordBase.java:528)
at com.et.ar.ActiveRecordBase.findAll(ActiveRecordBase.java:453)
at controllers.UserController.index(UserController.java:35)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.et.mvc.Controller.invoke(Controller.java:152)
at com.et.mvc.Dispatcher.service(Dispatcher.java:123)
at com.et.mvc.DispatcherFilter.doFilter(DispatcherFilter.java:251)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:99)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1008)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:589)
at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:1852)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

Answer 1

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