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

This answer, contrary to annon01's, properly decodes the keys and values. It does not use String.split, but scans the string using indexOf, which is faster.

public static Map parseQueryString(String qs) {
    Map result = new HashMap<>();
    if (qs == null)
        return result;

    int last = 0, next, l = qs.length();
    while (last < l) {
        next = qs.indexOf('&', last);
        if (next == -1)
            next = l;

        if (next > last) {
            int eqPos = qs.indexOf('=', last);
            try {
                if (eqPos < 0 || eqPos > next)
                    result.put(URLDecoder.decode(qs.substring(last, next), "utf-8"), "");
                else
                    result.put(URLDecoder.decode(qs.substring(last, eqPos), "utf-8"), URLDecoder.decode(qs.substring(eqPos + 1, next), "utf-8"));
            } catch (UnsupportedEncodingException e) {
                throw new RuntimeException(e); // will never happen, utf-8 support is mandatory for java
            }
        }
        last = next + 1;
    }
    return result;
}