java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/json/JsonMapper

IDEA运行SSM项目时，出现问题：
Handler dispatch failed; nested exception is java.lang.NoClassDefFoundError: com/fasterxml/jackson/databind/json/JsonMapper
原因：
项目引入的JSON依赖版本为：

<dependency> 
      <groupId>com.fasterxml.jackson.core</groupId>  
      <artifactId>jackson-databind</artifactId>  
      <version>2.9.0</version> 
    </dependency>

版本低了，改为高版本即可：

<dependency> 
      <groupId>com.fasterxml.jackson.core</groupId>  
      <artifactId>jackson-databind</artifactId>  
      <version>2.10.3</version> 
    </dependency>