https://blog.csdn.net/gnail_oug/article/details/80239767
参考这里Spring Boot教程(十一)：Spring Boot集成fastjson
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-json</artifactId>
</exclusion>
</exclusions>
</dependency>
一定要加上这个exclusions
