树莓派3代以下的wheezy系统：
nano或者vi 编辑 /etc/apt/sources.list 文件
换成：
deb http://mirrors.aliyun.com/raspbian/raspbian/ wheezy main non-free contrib
deb-src http://mirrors.aliyun.com/raspbian/raspbian/ wheezy main non-free contrib
执行：apt-get update && apt-get upgrade -y
树莓派3代以上的jessie 系统：
deb http://mirrors.tuna.tsinghua.edu.cn/raspbian/raspbian/ jessie main non-free contrib deb-src http://mirrors.tuna.tsinghua.edu.cn/raspbian/raspbian/ jessie main non-free contrib
新增（未测试）：
#deb http://mirrordirector.raspbian.org/raspbian/ jessie main contrib non-free rpi deb http://mirrors.aliyun.com/raspbian/raspbian/ jessie main contrib non-free rpi #deb http://mirrors.sohu.com/raspbian/raspbian/ jessie main contrib non-free rpi #deb http://mirrors.ustc.edu.cn/raspbian/raspbian/ jessie main contrib non-free rpi #deb http://ftp.jaist.ac.jp/pub/Linux/raspbian-archive/raspbian/ jessie main contrib non-free rpi
执行：apt-get update && apt-get upgrade -y
