url encode

http%3a%2f%2fwww.baidu.com%2fa-b%2fc+d
http://www.baidu.com/a-b/c d
空格+
/ %2f
: %3a

http%3a%2f%2fwww.baidu.com%2fa-b%2fc+d%3fa%3db%26c%3dd
%3d =
%26 &