NoClassDefFoundError: org/apache/commons/fileupload/FileItemFactory

原因，org.springframework.web.multipart.commons.CommonsMultipartResolver需要依赖commons-fileupload包。
maven导入commons-fileupload即可。

<dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.3.1</version>
        </dependency>