本文主要是介绍javaee中的错误，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
错误：Creation of SecureRandom instance for session ID generation using [SHA1PRNG] took [273] milliseconds.java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1305)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1139)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:264)
at chap08.listener.DBManagerListener.contextInitialized(DBManagerListener.java:53)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4811)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5251)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
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)
四月 29, 2018 9:08:34 上午 org.apache.coyote.AbstractProtocol start
信息: Starting ProtocolHandler ["http-nio-8080"]
四月 29, 2018 9:08:34 上午 org.apache.coyote.AbstractProtocol start
信息: Starting ProtocolHandler ["ajp-nio-8009"]
四月 29, 2018 9:08:34 上午 org.apache.catalina.startup.Catalina start
信息: Server startup in 1843 ms
java.lang.NullPointerException
at chap08.bean.DBProcess.exePrepare(DBProcess.java:94)
at chap08.bean.DBProcess.save(DBProcess.java:41)
at chap08.controll.Controller.doPost(Controller.java:49)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:648)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at chap08.filter.EncodeFilter.doFilter(EncodeFilter.java:39)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:616)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:522)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1095)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:672)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1502)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1458)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:745)
遇到错误之后上网查找，都是关于tomcat的问题，我配置了感觉也不行，这时候看到了com.mysql.jdbc.Driver
想起是不是缺少jar包，将jar包导入，果然错误解决
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