1. 添加ppa源
sudo add-apt-repository ppa:ondrej/php
2. 升级源
sudo apt-get update && sudo apt-get upgrade
3. sudo apt-get install php7.0-mcrypt
安装php7的方法
sudo apt-get install php7.0 php7.0-mysql libapache2-mod-php7.0 php7.0-mcrypt php7.0-curl
