networking android club 2015. networking asynctask httpurlconnection json parser

Networking

Android Club 2015

Networking

• AsyncTask• HttpUrlConnection• JSON Parser

Thread

• UI thread• Background thread

AsyncTask

• Helps us to manage process of backgroud thread

• Started from UI thread

AsyncTask: 3 parameters

• 1. Params• 2. Progess• 3. Result

AsyncTask: example

• TimeUnit.SECONDS.sleep(10);

AsyncTask: practice

• Create public static ProgressDialog in Activity

• Create AsyncTask• onPreExecute: set message to dialog• onPreExecute: show progress dialog• onPostExecute: dismiss dialog

AsyncTask: pass data

• HttpTask task = new HttpTask();task.execute(3);

• TimeUnit.SECONDS.sleep(params[0]);

Pass data: practice

• Change previous code so that it should wait twice amount of time

• If you pass 3, it should wait 6 seconds• If 10, then 20

Networking: easiest way

1. Add permission: INTERNET2. Create AsyncTask3. Create HttpUrlConnection4. Convert InputStream to String5. Update UI6. Start from UI

Step 1: Add permission

• Open AndroidManifest.xml• Add this permission: <uses-

permission android:name="android.permission.INTERNET"/>

Step 2: Create AsynkTask

public class HttpTask extends AsyncTask<String, String, String> {

@Override protected String doInBackground(String... params) { return null; }

@Override protected void onPostExecute(String s) {

}

}

Step 3: HttpUrlConnection

• URL url = new URL(params[0]);HttpURLConnection connection = (HttpURLConnection) url.openConnection();connection.connect();

Step 4: InputString to String

• InputStream stream = connection.getInputStream();InputStreamReader isReader = new InputStreamReader(stream );BufferedReader buffer = new BufferedReader(isReader );StringBuilder content = new StringBuilder();String line;while ((line = buffer.readLine()) != null) { content.append(line);}

Step 5: Update UI

• MainActivity.tvData.setText(s);

Step 6: Start from UI

• HttpTask task = new HttpTask();String url = "http://jsonip.com";task.execute(url);

HttpUrlConnection: practice

http://www.telize.com/geoip?callback=YOUR_IP

1. Create new AsyncTask2. Get content using HttpUrlConnection3. Convert content InputStream to String4. Update UI5. Pass that URL to AsyncTask

Parsing JSON: example

• JSONObject object = new JSONObject(s);String ip = object.getString("ip");MainActivity.tvData.setText("My ip address is "+ip);

Parsing JSON: practice

• http://www.telize.com/geoip?callback=YOUR_IP

• Show latitude• Show longitude• Show ISP• Show country

Homework 1: Forecast.IO

• developer.forecast.io

Homework 2: Football-api.com

• http://football-api.com• Demo - EPL• Free• English Premier League• Access limit: 1000 requests per hour• Access from 1 IP address

Homework 3: Your own API

• Create your own API• For example: calculator

for communal services