java - How to convert map to url query string?

Question

Do you know of any utility class/library, that can convert Map into URL-friendly query string?

Example:

I have a map:

"param1"=12,
"param2"="cat"

I want to get:

param1=12&param2=cat

final output

relativeUrl+param1=12&param2=cat

Answer 1

The most robust one I saw off-the-shelf is the URLEncodedUtils class from Apache Http Compoments (HttpClient 4.0).

The method URLEncodedUtils.format() is what you need.

It doesn't use map so you can have duplicate parameter names, like,

  a=1&a=2&b=3

Not that I recommend this kind of use of parameter names.