<dependency>

             <groupId>com.fasterxml.jackson.core</groupId>

             <artifactId>jackson-databind</artifactId>

             <version>2.9.3</version>

         </dependency>

         <dependency>

             <groupId>com.fasterxml.jackson.core</groupId>

             <artifactId>jackson-core</artifactId>

             <version>2.9.3</version>

         </dependency>

         <dependency>

             <groupId>com.fasterxml.jackson.core</groupId>

             <artifactId>jackson-annotations</artifactId>

             <version>2.9.3</version>

 </dependency>

 <!-- 使用默认的注解映射 -->

 <mvc:annotation-driven />

  @RequestMapping("/getJson")

     @ResponseBody

     public Object getJson(){

         User user = new User();

         user.setId("123");

         user.setName("里哈");

         return user;

     }