// Izin menggunakan Internet
<uses-permission 
	android:name="android.permission.INTERNET"/>

// Izin cek status jaringan
<uses-permission    
    android:name="android.permission.ACCESS_NETWORK_STATE"/>

---

// Cek koneksi jaringan
ConnectivityManager connMgr = 
		(ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();

if (networkInfo != null && networkInfo.isConnected()) {
    // Create background thread to connect and get data
    new DownloadWebpageTask().execute(stringUrl);
} else {
    textView.setText("No network connection available.");
}

---

// Cek jaringan WiFi dan Mobile
NetworkInfo networkInfo = 
    connMgr.getNetworkInfo(ConnectivityManager.TYPE_WIFI);
boolean isWifiConn = networkInfo.isConnected();

networkInfo = 
    connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
boolean isMobileConn = networkInfo.isConnected();

---

// Gunakan worker thread
AsyncTask 		   : kerjaan yang sangat pendek, atau tidak ada hasil yang dikembalikan ke UI
AsyncTaskLoader    : untuk kerjaan yang lebih panjang, atau yang mengambalikan ke UI
Background Service : pembahasan lain

---

Dalam background task (contoh di doInBackground())
1. Buat URI
2. Buat koneksi HTTP
3. Unduh Data

---

/* 1. Buat URI untuk request
 * 	  contoh API URL: https://www.googleapis.com/books/v1/volumes?q=pride+prejudice&maxResults=5&printType=books
 */

final String BASE_URL = 
	"https://www.googleapis.com/books/v1/volumes?";    
final String QUERY_PARAM = "q"; 
final String MAX_RESULTS = "maxResults"; 
final String PRINT_TYPE = "printType";
Uri builtURI = Uri.parse(BASE_URL).buildUpon()
       .appendQueryParameter(QUERY_PARAM, "pride+prejudice")
       .appendQueryParameter(MAX_RESULTS, "10")
       .appendQueryParameter(PRINT_TYPE, "books")
       .build();
URL requestURL = new URL(builtURI.toString());


/* 2. Buat koneksi HTTP dan dapatkan respon
 * 
 * Buat koneksi dari nol (from scratch)
 * - GUnakan HttpURLConnection
 * - Harus dilakukan di thread yang terpisah
 * - Membutuhkan InputStreams dan blok try/catch
 *
 */

HttpURLConnection conn = 
		(HttpURLConnection) requestURL.openConnection();

try {
	// Konfigurasi koneksi
    conn.setReadTimeout(10000 /* milliseconds */);
    conn.setConnectTimeout(15000 /* milliseconds */);
    conn.setRequestMethod("GET");
    conn.setDoInput(true);

    // 3. Hubungkan dan dapatkan respon
    conn.connect();
    int response = conn.getResponseCode();

    InputStream is = conn.getInputStream();
    String contentAsString = convertIsToString(is, len);

	return contentAsString;
} finally {
	conn.disconnect();
	if (is != null) {
		is.close();
	}
}

---

/*
 * Konversi stream input menjadi string
 */
public String convertIsToString(InputStream stream, int len) 
    throws IOException, UnsupportedEncodingException {
    
    Reader reader = null;
    reader = new InputStreamReader(stream, "UTF-8");
    char[] buffer = new char[len];
    reader.read(buffer);
    return new String(buffer);
}

// Gunakan BufferedReader agar lebih efisien
StringBuilder builder = new StringBuilder();
BufferedReader reader = 
	new BufferedReader(new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
   builder.append(line + "\n");
}
if (builder.length() == 0) {
   return null;
}
resultString = builder.toString();