415 org.springframework.web.HttpMediaTypeNotSupportedException Content type ‘null’ not supported

在用Postman调用微服务的时候，发现一直出现错误：

{
"timestamp": 1529391330656,
"status": 415,
"error": "Unsupported Media Type",
"exception": "org.springframework.web.HttpMediaTypeNotSupportedException",
"message": "Content type 'null' not supported",
"path": "/cities/4"
}
发现在controller上面都是 produces = "application/json;charset=UTF-8", consumes = "application/json;charset=UTF-8" 参数的传递只能是json的形式，于是找到解决问题的办法是，在Postman中Headers中增加

Content-Type : application/json