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         


        

Answer 1

For multivalue map you can do like below (using java 8 stream api's)

Url encoding has been taken cared in this.

MultiValueMap params =  new LinkedMultiValueMap<>();
String urlQueryString = params.entrySet()
            .stream()
            .flatMap(stringListEntry -> stringListEntry.getValue()
                    .stream()
                    .map(s -> UriUtils.encode(stringListEntry.getKey(), StandardCharsets.UTF_8.toString()) + "=" +
                            UriUtils.encode(s, StandardCharsets.UTF_8.toString())))
            .collect(Collectors.joining("&"));