Why does volley's response string use an encoding different from that in the response headers?

Question

When doing a volley request (either StringRequest or JsonObjectRequest), using the OkHttp stack, the response string's encoding is set to ISO-8995-1, which is the default encoding. The response has a header: content-type=text/html; charset=utf-8, which should be detected. Why isn't it?

Answer 1

Both of those request types call HttpHeaderParser.parseCharset, which is able to determine the charset from the headers. However, it requires that the header be Content-Type, not content-type: it is case sensitive. (I'm not sure of the behavior if using the default HurlStack, it's possible this is an implementation detail difference with the OkHttp stack.)

Solution 1: copy the original request type, but manually override the charset

Solution 2: copy the original request type, but force the expected header to exist

import com.android.volley.NetworkResponse;
import com.android.volley.ParseError;
import com.android.volley.Response;
import com.android.volley.Response.ErrorListener;
import com.android.volley.Response.Listener;
import com.android.volley.toolbox.HttpHeaderParser;
import com.android.volley.toolbox.JsonRequest;

import org.json.JSONException;
import org.json.JSONObject;

import java.io.UnsupportedEncodingException;

public class JsonUTF8Request extends JsonRequest<JSONObject> {
    public JsonUTF8Request(int method, String url, JSONObject jsonRequest,
                           Listener<JSONObject> listener, ErrorListener errorListener) {
        super(method, url, (jsonRequest == null) ? null : jsonRequest.toString(), listener,
                errorListener);
    }

    @Override
    protected Response<JSONObject> parseNetworkResponse(NetworkResponse response) {
        try {
            // solution 1:
            String jsonString = new String(response.data, "UTF-8");
            // solution 2:
            response.headers.put(HTTP.CONTENT_TYPE,
                response.headers.get("content-type"));
            String jsonString = new String(response.data, HttpHeaderParser.parseCharset(response.headers));
            //
            return Response.success(new JSONObject(jsonString),
                    HttpHeaderParser.parseCacheHeaders(response));
        } catch (UnsupportedEncodingException e) {
            return Response.error(new ParseError(e));
        } catch (JSONException je) {
            return Response.error(new ParseError(je));
        }
    }
}