$ sudo gedit /etc/apt/apt.conf
edit:
Acquire::http::proxy "http://jalen_chu:Oct%402015@172.26.100.238:64000/";
Acquire::https::proxy "https://jalen_chu:Oct%402015@172.26.100.238:64000/";
Acquire::ftp::proxy "ftp://jalen_chu:Oct%402015@172.26.100.238:64000/";
Acquire::socks::proxy "socks://jalen_chu:Oct%402015@172.26.100.238:64000/";
@ use %40 to display!
（@字符是特殊字符，使用 %40 替换）
