maven中新增

      <dependency>
          <groupId>com.fasterxml.jackson.core</groupId>
          <artifactId>jackson-core</artifactId>
          <version>2.2.4</version>
      </dependency>
      <dependency>
          <groupId>com.fasterxml.jackson.core</groupId>
          <artifactId>jackson-databind</artifactId>
          <version>2.2.4</version>
      </dependency>
 

就好了