https://www.jianshu.com/p/2b03a812d588
https://my.oschina.net/sdlvzg/blog/1800395
异常:org.springframework.web.client.RestClientException: Could not extract 的解决方法:(使用String.class即可,如果返回String的话,可以在下面的页面中搜索“String”)
https://www.cnblogs.com/jeffwongishandsome/archive/2018/05/17/8995562.html