运行镜像后，curl http://localhost 为什么拒绝连接

Dockerfile如下：

FROM ubuntu

MAINTAINER xbf

RUN sed -i 's/archive.ubuntu.com/mirrors.ustc.edu.cn/g' /etc/apt/sources.list  

RUN apt-get update

RUN apt-get install -y nginx

COPY index.html /var/www/html

ENTRYPOINT ["/usr/sbin/nginx","-g","daemo off;"]

EXPOSE 80