报奇怪找不到类异常，明明包都导入添加了
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.web.servlet.view.ContentNegotiatingViewResolver#0' defined in ServletContext resource [/WEB-INF/configs/spring/mvc-dispatcher-servlet.xml]: Initialization of bean failed; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/core/JsonGenerator
