HTTP URL Address Encoding in Java

Question

My Java standalone application gets a URL (which points to a file) from the user and I need to hit it and download it. The problem I am facing is that I am not able to encod

Answer 1

I agree with Matt. Indeed, I've never seen it well explained in tutorials, but one matter is how to encode the URL path, and a very different one is how to encode the parameters which are appended to the URL (the query part, behind the "?" symbol). They use similar encoding, but not the same.

Specially for the encoding of the white space character. The URL path needs it to be encoded as %20, whereas the query part allows %20 and also the "+" sign. The best idea is to test it by ourselves against our Web server, using a Web browser.

For both cases, I ALWAYS would encode COMPONENT BY COMPONENT, never the whole string. Indeed URLEncoder allows that for the query part. For the path part you can use the class URI, although in this case it asks for the entire string, not a single component.

Anyway, I believe that the best way to avoid these problems is to use a personal non-conflictive design. How? For example, I never would name directories or parameters using other characters than a-Z, A-Z, 0-9 and _ . That way, the only need is to encode the value of every parameter, since it may come from an user input and the used characters are unknown.