异常描述：项目中已经导入jacksonmapper 的jar ，访问项目依然报如下异常。
HTTP Status 500 - javax.servlet.ServletException: Servlet.init() for servlet tool threw exception root cause org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'jacksonMessageConverter' defined in ServletContext resource [/WEB-INF/tool-servlet.xml]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [org.springframework.http.converter.json.MappingJacksonHttpMessageConverter]: Constructor threw exception; nested exception is java.lang.NoClassDefFoundError: org/codehaus/jackson/map/ObjectMapper解决方法：因为项目中引用的其他依赖中也有该jar，产生冲突导致（排除法解决，spring的相关依赖就有该jar）。
版权声明：本文为weixin_38777744原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接和本声明。