HttpPostTask.java

package me.ccrama.redditslide.Synccit.http;

import android.os.AsyncTask;
import android.util.Log;
import android.util.Pair;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;

import okhttp3.MultipartBody;
import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public abstract class HttpPostTask<Result> extends AsyncTask<String, Long, Result> {

	private static final String TAG = HttpPostTask.class.getSimpleName();
	private static final int CONNECTION_TIMEOUT_MILLIS = 5000;
	private static final int SOCKET_TIMEOUT_MILLIS = 20000;

	private final OkHttpClient mClient = HttpClientFactory.getOkHttpClient().newBuilder()
			.readTimeout(SOCKET_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS)
			.connectTimeout(CONNECTION_TIMEOUT_MILLIS, TimeUnit.MILLISECONDS).build();

	private String mUrl;

	/**
	 * @param url Required.
	 */
	public HttpPostTask(String url) {
		mUrl = url;
	}

	/**
	 * params come in pairs: key/value
	 */
	@Override
	protected Result doInBackground(String... params) {

		List<Pair<String, String>> nvps = getPostArgs(params);
        MultipartBody.Builder formBuilder = new MultipartBody.Builder().setType(MultipartBody.FORM);

		for(Pair<String, String> p : nvps) {
            formBuilder.addFormDataPart(p.first, p.second);
		}

		Request request = new Request.Builder().url(mUrl)
				.header("User-Agent", getUserAgent()).addHeader("Content-Encoding", "gzip")
				.post(formBuilder.build())
				.build();
		try {
			Response res = mClient.newCall(request).execute();
			if (!res.isSuccessful()) {
				throw new IOException("Unexpected code " + res);
			}

			return onInput(res.body().string());

		} catch (Exception ex) {
			Log.e(TAG, "Error during POST", ex);
		}
		return null;
	}

		private List<Pair<String, String>> getPostArgs(String... params) {
			List<Pair<String, String>> nvps = new ArrayList<>();

			for (int i = 0; i < params.length; i += 2) {
			try {
				nvps.add(new Pair<>(params[i], params[i+1]));
			} catch (ArrayIndexOutOfBoundsException ex) {
				Log.e(TAG, "Params didn't come in name/value pairs", ex);
			}
		}
		return nvps;
	}

	protected Result onInput(String in) throws Exception {
		return null;
	}

	protected abstract String getUserAgent();

}