记录问题：在springboot中servletlet调用service方法空指针异常问题

1.异常：

[2018-03-11 16:16:59.929] - 5940 严重 [http-nio-8666-exec-1] --- org.apache.catalina.core.ContainerBase.[Tomcat-1].[localhost].[/].[fileUpload]: Servlet.service() for servlet [fileUpload] in context with path [] threw exception[2018-03-11 16:16:59.929] - 5940