Mavzu: Android ilovalarida tarmoqli dasturlash bilan ishlash. Reja Mobil ilovalarda tarmoqqa ulanishni tekshirish

Mavzu: Android ilovalarida tarmoqli dasturlash bilan ishlash.
Reja
1. Mobil ilovalarda tarmoqqa ulanishni tekshirish
3. HTTP orqali serverga ulanish.
4. JSON xizmatidan foydalanish

Mobil ilovalarda tarmoqqa ulanishni tekshirish
Hozirgi kunda internet tarmogʼi barcha sohalarda rivojlanib ulgurgan. Demak biz mobil qurilmalardan foydalanish jarayonida faqat SMS/MMS yoki elektron pochta xabaralari emas balki internet xizmatlaridan foydalanishimiz mumkin.
Buning uchun ilovalarni yaratishda tarmoqda dasturlash, yaʼni, maxsus protokollar (HTTP), maxsus metodlar (GET, POST), maʼlumotlarni yuklab olish va boshqa xizmatlar (JSON) dan foydalanish koʼnikmalariga ega boʼlishimiz lozim.
Tarmoqqa ulanishni tekshirish
Demak tarmoq bilan ishlash jarayonida birinchi boʼlib, tarmoq holatini yaʼni ulanganlik holatini tekshirib koʼramiz.Аndroid tizimida buning uchun ConnectivityManager sinfidan foydalaniladi. Ushbu sinf orqali yaratilgan obʼekt getSystemService() metodini chaqirish orqali initsializatsiya qilinadi. Ushbu holat boʼyicha quyida dastur kodi keltirilgan:
ConnectivityManager check = (ConnectivityManager) this.context.getSystemService(Context.CONNECTIVITY_S ERVICE);
Bundan keyin biz tarmoq haqidagi maʼlumotni toʼliq olishimiz kerak boʼladi. Buning uchun getAllNetworkInfo metodidan foydalaniladi. Ushbu metodi NetworkInfo tipidagi massiv qaytaradi va quyidagicha foydalaniladi:
NetworkInfo[] info = check.getAllNetworkInfo();
Endi ushbu info nomli massivga kelgan qiymat orqali ilova tarmoqqa ulanganligini tekshirish uchun getState metodidan foydalaniladi:
for (int i = 0; iif (info[i].getState() == NetworkInfo.State.CONNECTED){
Toast.makeText(context, "Internet is connected
Toast.LENGTH_SHORT).show();
}
}
Bundan tashqari tarmoq holatini tekshirish uchun quyidagi konstatntalardan foydalaniladi:
№ State
1 CONNECTING
2 DISCONNECTED
3 DISCONNECTING
4 SUSPENDED
5 UNKNOWN
HTTP orqali serverga ulanish
Internet borligini tekshirganimizdan keyin ushbu tarmoq orqali turli xil operatsiyalar amalga oshirishimiz mumkin. Misol uchun internet orqali matn yoki binary (misol uchun rasm) maʼlumotlarni yuklab olish va h.k.lar.
Android tizimida ushbu operatsiyalarni amalga oshirish uchun HttpURLConnection va
URL sinflaridan foydalaniladi. Quyidag kod qismi orqali koʼrsatilgan internet manzil uchun url obʼekti yaratiladi:
String link = "http://www.google.com";
URL = new URL(link);
HTTP orqali serverga ulanish
url yaratilgandan keyin HttpURLConnection sinfiga joʼnatiladi va HttpURLConnection obʼekti koʼrsatilgan internet manzili bilan bogʼlanadi. Bu bogʼlanishni esa HttpURLConnection sinfining connect metodidan foydalanib quyidagicha amalga oshiriladi. HttpURLConnection conn = (HttpURLConnection) url.openConnection(); conn.connect();
Demak ushbu bogʼlanish orqali mazkur sahifa HTML hujjati kodini oʼqib olamiz. Maʼlumotlarni oʼqib olish uchun esa InputStream va BufferedReader sinflaridan foydalaniladi.
Quyida misol keltirilgan:
InputStream is = conn.getInputStream();
BufferedReader reader =new BufferedReader(new InputStreamReader(is, "UTF-8"));
String webPage = "",data=""; while ((data = reader.readLine()) != null){
webPage += data + "\n";
}
HttpURLConnection sinfining quyidagicha metodlari mavjud. Quyidagi jadvalda connect() metodidan boshqa metodlar ham keltirilgan:
№ Metod
1 disconnect() – internet bogʼlanishni tugatish uchun ishlatiladi
2 getRequestMethod() – ushbu metod joriy ishlab turgan serverning HTTP metodini qaytaradi
3 getResponseCode() – masofadagi HTTP server “response code” qaytaradi
4 setRequestMethod (String method) - HTTP server
tomonidan soʼralgan metodni oʼrnatadi
5 usingProxy() - proxy server mavjud yoki yoʼqligini qaytaradi
Internet bogʼlanishni tekshirish
1. Yangi Android loyiha yaratamiz va uni Networking deb nomlaymiz.
2. Ilovaning AndroidManifest.xml fayliga quyidagi “permission” qoʼshib qoʼyiladi:

3. MainAcivity.java fayli mos holda oʼzgartiriladi
4. activity_main.xml fayli ham mos holda oʼzgartiriladi
activity_main.xml

xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent" >


//Package name here MainActivity.java import android.app.Activity; import android.os.Bundle;
import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL; import java.net.URLConnection; import android.util.Log; public class MainActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main);
}
public void checkInternetConnection(){
…..
}
}
MainActivity.java-> checkInternetConnection(){…..}
ConnectivityManager check = (ConnectivityManager) this.context.
getSystemService(Context.CONNECTIVITY_SERVICE); if (check != null)
{
NetworkInfo[] info = check.getAllNetworkInfo(); if (info != null)
for (int i = 0; i {
Toast.makeText(context, "Internet is connected",
Toast.LENGTH_SHORT).show();
} }
else{
Toast.makeText(context, "not conencted to internet",
Toast.LENGTH_SHORT).show();
}
Binary maʼlumotlarni yuklab olish
 Yangi DownloadData nomli Аndroid loyiha yaratamiz
 Loyihaning main.xml faylini quyidagicha oʼzgartiramiz




AndroidManifest.xml fayliga quyidagi permission qoʼshib qoʼyiladi

MainActivity.java // Package nomi loyihangizga mos qoldiring // Kerakli sinflarni import qiling public class MainActivity extends Activity { ImageView img;
private InputStream OpenHttpConnection(String urlString) throws IOException{
InputStream in = null; int response = -1;
URL url = new URL(urlString);
URLConnection conn = url.openConnection(); if (!(conn instanceof HttpURLConnection)) throw new IOException(“Not an HTTP connection”);
try{
HttpURLConnection httpConn = (HttpURLConnection) conn;
httpConn.setAllowUserInteraction(false); httpConn.setInstanceFollowRedirects(true); httpConn.setRequestMethod(“GET”); httpConn.connect();
response = httpConn.getResponseCode(); if (response == HttpURLConnection.HTTP_OK) { in = httpConn.getInputStream(); } }
catch (Exception ex){
Log.d(“Networking”, ex.getLocalizedMessage()); throw new IOException(“Error connecting”);}
return in;
}
private Bitmap DownloadImage(String URL) MainActivity.java
{
Bitmap = null;
InputStream in = null; try {
in = OpenHttpConnection(URL); bitmap = BitmapFactory.decodeStream(in); in.close();
} catch (IOException e1) {
Log.d(“NetworkingActivity”, e1.getLocalizedMessage());
} return bitmap;
}
private class DownloadImageTask extends AsyncTask { protected Bitmap doInBackground(String... urls) { return DownloadImage(urls[0]);
}
protected void onPostExecute(Bitmap result) {
ImageView img = (ImageView) findViewById(R.id.img); img.setImageBitmap(result); }
}
MainActivity.java
@Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); new DownloadImageTask().execute(
“http://www.mayoff.com/5-01cablecarDCP01934.jpg”);
}
} // MainActivity sinfi
Izoh:
Dastur natijasi sifatida koʼrsatilgan manzil boʼyicha rasm yuklab olinadi va ilovadagi ga rasm yuklanadi
Dastur natijasi
Matn maʼlumotlarni yuklab olish
Yuqoridagi loyihaning MainActivity.java fayliga quyidagi kod qismi qoʼshiladi private String DownloadText(String URL)
{ int BUFFER_SIZE = 2000; InputStream in = null;
try { in = OpenHttpConnection(URL); } catch (IOException e) {
Log.d(“Networking”, e.getLocalizedMessage()); return “”;
}
InputStreamReader isr = new InputStreamReader(in); int charRead; String str = “”;
char[] inputBuffer = new char[BUFFER_SIZE]; try { while ((charRead = isr.read(inputBuffer))>0) {
String readString =
String.copyValueOf(inputBuffer, 0, charRead); str += readString;
inputBuffer = new char[BUFFER_SIZE];
}
in.close();
} catch (IOException e) {
Log.d(“Networking”, e.getLocalizedMessage()); return “”;
}
return str;
}
private class DownloadTextTask extends AsyncTask { protected String doInBackground(String... urls) { return DownloadText(urls[0]);
}
@Override
protected void onPostExecute(String result) {
Toast.makeText(getBaseContext(), result, Toast.LENGTH_LONG).show(); }
}
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main);
//---download text---
String str = DownloadText("http://www.appleinsider.com/appleinsider.rss");
Toast.makeText(getBaseContext(), str, Toast.LENGTH_SHORT).show();
// WordDefinition("Apple");
}
JSON xizmatidan foydalanish
JSON – inglizcha JavaScript Object Notation soʼzlarining bosh harflaridan olingan boʼlib, tarmoq orqali maʼlumot oʼqish va yozish uchun qulay va tez xizmat hisoblanadi
JSON xizmatining quyidagi sinflari mavjud
JSONArray
JSONObject
JSONStringer
JSONTokenizer
JSON komponentlarai
Array([) - JSON data massivi (obʼektlar birlashmasi)
Objects({) - - JSON obʼekti
Key – obʼektning kaliti Value – obʼekt qiymati
JSON maʼlumot koʼrinishi
JSON dan foydalanish
1. Yangi Аndroid loyiha yaratamiz va uni UsingJSON deb nomlaymiz
2. Loyiha quyidagi fayllardan iborat quyidagi slaydlarda koʼrsatilganidek oʼzgartiramiz
3. res/layout/activity_main.xml
4. res/values/string.xml
5. AndroidManifest.xml
6. src/package/MainActivity.java
7. src/package/HandleJSON.java
android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context=".MainActivity" >




android:textAppearance="?android:attr/textAppearanceSmall" />








res/values/string.xml


JSONParser Settings
Hello world!
Location
Country:
Temperature:
Humidity:
Pressure:
Weather

src/package/MainActivity.java
public class MainActivity extends Activity {
private String url1 = "http://api.openweathermap.org/data/2.5/weather?q="; private EditText location,country,temperature,humidity,pressure; private HandleJSON obj;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); location = (EditText)findViewById(R.id.editText1); country = (EditText)findViewById(R.id.editText2); temperature = (EditText)findViewById(R.id.editText3); humidity = (EditText)findViewById(R.id.editText4); pressure = (EditText)findViewById(R.id.editText5);
}
public void open(View view){
String url = location.getText().toString();
String finalUrl = url1 + url;
country.setText(finalUrl); obj = new HandleJSON(finalUrl); obj.fetchJSON();
while(obj.parsingComplete); country.setText(obj.getCountry()); temperature.setText(obj.getTemperature()); humidity.setText(obj.getHumidity()); pressure.setText(obj.getPressure());
}
}
public class HandleJSON {
private String country = "county"; private String temperature = "temperature"; private String humidity = "humidity"; private String pressure = "pressure"; private String urlString = null;
public volatile boolean parsingComplete = true; public HandleJSON(String url){ this.urlString = url;
}
public String getCountry(){
return country; }
public String getTemperature(){
return temperature;
}
public String getHumidity(){
return humidity; }
public String getPressure(){
return pressure;
}
………………
………………
@SuppressLint("NewApi") public void readAndParseJSON(String in) { try {
JSONObject reader = new JSONObject(in);
JSONObject sys = reader.getJSONObject("sys"); country = sys.getString("country");
JSONObject main = reader.getJSONObject("main"); temperature = main.getString("temp");
pressure = main.getString("pressure"); humidity = main.getString("humidity"); parsingComplete = false;
} catch (Exception e) {
// TODO Auto-generated catch block e.printStackTrace();
}
}
…………….
………………
public void fetchJSON(){
Thread = new Thread(new Runnable(){
@Override public void run() { try {
URL = new URL(urlString);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(10000 /* milliseconds */); conn.setConnectTimeout(15000 /* milliseconds */); conn.setRequestMethod("GET"); conn.setDoInput(true); // Starts the query conn.connect();
InputStream stream = conn.getInputStream(); String data = convertStreamToString(stream); readAndParseJSON(data); stream.close();
} catch (Exception e) {
e.printStackTrace();
}
}
});
thread.start();
}
static String convertStreamToString(java.io.InputStream is) {
java.util.Scanner s = new java.util.Scanner(is).useDelimiter("\\A"); return s.hasNext() ? s.next() : "";
}
}
AndroidManifest.xml fayliga permission quyidagicha qoʼshiladi




……

Dastur natijasi 
Foydalanilgan adabiyotlar
1. Beginning AndroidTM 4 Application Development”, by WeiMeng Lee, printed at Radha Offset, Delhi in 2013, pages – 533. Chapter-10. Networking
2. “AndroidTM Application Development Cookbook”, by WeiMeng Lee, printed at Sharda Offset Press, Delhi in 2013,
Chapter-6. Network programming
3. http://www.tutorialspoint.com/android/android_network_connec tion.htm
4. http://www.tutorialspoint.com/android/android_json_parser.htm