spring boot访问报错

spring boot启动时报错，信息如下

This application has no explicit mapping for /error, so you are seeing this as a fallback.

Thu Apr 12 15:22:47 CST 2018
There was an unexpected error (type=Not Found, status=404).

No message available

找了半天说时配置的不对，我想了一下，总共就写了六行代码，就配置了一个controller，怎么能不对呢，再仔细看看，404，路径不对，然后尝试在地址栏路径中去掉了项目名称，结果好使了，原来spring boot直接是   http://hostname:port/xxxxxx形式访问的，不许要向之前项目一样，加上项目名称才访问