How do you unescape URLs in Java?

Question

When I read the xml through a URL's InputStream, and then cut out everything except the url, I get "http://cliveg.bu.edu/people/sganguly/player/%20Rang%20De%20Basanti%20-%20Tu%20Bin%20Bataye.mp3".

As you can see, there are a lot of "%20"s.

I want the url to be unescaped.

Is there any way to do this in Java, without using a third-party library?

Tva

Just to be pedantic, there is no such thing as "normal unicode". UTF8 is one of several ways to represent unicode text. But there is no "true" canonical representation. – Fantastic

As Jon and ng said, this has nothing to do with Unicode or UTF-8. You might want to change the title. – Consolation

The answer marked as correct now it is clearly wrong and should be removed. – Bicker

Answer 1

This is not unescaped XML, this is URL encoded text. Looks to me like you want to use the following on the URL strings.

URLDecoder.decode(url);

This will give you the correct text. The result of decoding the like you provided is this.

http://cliveg.bu.edu/people/sganguly/player/ Rang De Basanti - Tu Bin Bataye.mp3

The %20 is an escaped space character. To get the above I used the URLDecoder object.

Breakdown

That method is deprecated. Use URLDecoder.decode(location,"UTF-8"); – Mashie

Answer 2

Starting from Java 11 use

URLDecoder.decode(url, StandardCharsets.UTF_8).

for Java 7/8/9 use URLDecoder.decode(url, "UTF-8").

URLDecoder.decode(String s) has been deprecated since Java 5

Regarding the chosen encoding:

Note: The World Wide Web Consortium Recommendation states that UTF-8 should be used. Not doing so may introduce incompatibilites.

Bicker

for Java 8 & 9 Use URLDecoder.decode(s, "UTF-8"); – Tinytinya

Since Java 7 StandardCharsets. Am I wrong? – Bicker

yes, but the URLDecoder method decode only takes (String, String) in Java 8 – Tinytinya

@user16320675 I'd considered that - but will it work with the underscore rather than hyphen in "UTF-8" ? – Tinytinya

Thank you to share. I never knew about this handy method before I read this answer! One cool feature of URLDecoder.decode() vs new URI().getPath(): The URI ctor will reject decoded URLs! URLDecoder.decode() will accept both encoded and decoded URLs, e.g., (decoded) /path/to/here and there and (encoded) /path/to/here%20and%20there. – Bobsledding

Answer 3

I'm having problems using this method when I have special characters like á, é, í, etc. My (probably wild) guess is widechars are not being encoded properly... well, at least I was expecting to see sequences like %uC2BF instead of %C2%BF.

Edited: My bad, this post explains the difference between URL encoding and JavaScript's escape sequences: URI encoding in UNICODE for apache httpclient 4

Thuggee

Answer 4

In my case the URL contained escaped html entities, so StringEscapeUtils.unescapeHtml4() from apache-commons did the trick

Stratiform