How to obtain the query string in a GET with Java HttpServer/HttpExchange?

Question

I am trying to create a simple HttpServer in Java to handle GET requests, but when I try to get the GET parameters for a request I noticed the HttpExchange class does not have a

Answer 1

Stumbled across this, and figured I'd toss a Java 8 / Streams implementation out here, whilst adding a few extra bits (not in previous answers).

Extra 1: I've added a filter to avoid processing any empty params. Something that should not happen, but it allows a cleaner implementation vs. not handling the issue (and sending an empty response). An example of this would look like ?param1=value1¶m2=

Extra 2: I've leveraged String.split(String regex, int limit) for the second split operation. This allows a query parameter such as ?param1=it_has=in-it&other=something to be passed.

public static Map getParamMap(String query) {
    // query is null if not provided (e.g. localhost/path )
    // query is empty if '?' is supplied (e.g. localhost/path? )
    if (query == null || query.isEmpty()) return Collections.emptyMap();

    return Stream.of(query.split("&"))
            .filter(s -> !s.isEmpty())
            .map(kv -> kv.split("=", 2)) 
            .collect(Collectors.toMap(x -> x[0], x-> x[1]));

}

Imports

import java.util.Map;
import java.util.Collections;
import java.util.stream.Stream;
import java.util.stream.Collectors;