项目启动时报错 ：

The method getJspApplicationContext(ServletContext) is undefined for the type JspFactory

Stacktrace:] with root cause
org.apache.jasper.JasperException: Unable to compile class for JSP:

An error occurred at line: [31] in the generated java file: [E:\digdeep2\.metadata\.plugins\org.eclipse.wst.server.core\tmp0\work\Catalina\localhost\minisns\org\apache\jsp\index_jsp.java]
The method getJspApplicationContext(ServletContext) is undefined for the type JspFactory

Stacktrace:
    at org.apache.jasper.compiler.DefaultErrorHandler.javacError(DefaultErrorHandler.java:103)
    at org.apache.jasper.compiler.ErrorDispatcher.javacError(ErrorDispatcher.java:366)
    at org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:468)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:378)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:353)
    at org.apache.jasper.compiler.Compiler.compile(Compiler.java:340)
    at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:657)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:357)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    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:502)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
    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:409)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1044)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:313)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:744)

原因是：项目自带的servlet-api和tomcat中servlet-api冲突，

解决办法：

在 pom.xml文件中加入scope选项：

<dependency>

   <groupId>javax.servlet</groupId>

   <artifactId>servlet-api</artifactId>

   <version>2.4</version>

   <scope>provided</scope>

</dependency>

<dependency>

   <groupId>javax.servlet</groupId>

   <artifactId>jsp-api</artifactId>

   <version>2.0</version>

   <scope>provided</scope>

</dependency>