1.RFC3986
- reserved = gen-delims / sub-delims
gen-delims = ":" / "/" / "?" / "#" / "[" / "]" / "@"
sub-delims = "!" / "$" / "&" / "'" / "(" / ")" / "*" / "+" / "," / ";" / "=" 远程调用：浏览器 url 保留字符,做参数值的时候服务器不会收到
- unreserved = ALPHA / DIGIT / "-" / "." / "_" / "~"