samples/training/network-usage/src/com/example/android/networkusage/NetworkActivity.java - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2012 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
  * in compliance with the License. You may obtain a copy of the License at
  *
  * http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software distributed under the License
  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
  * or implied. See the License for the specific language governing permissions and limitations under
  * the License.
  */

 package com.example.android.networkusage;

 import android.app.Activity;
 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.SharedPreferences;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 import android.os.AsyncTask;
 import android.os.Bundle;
 import android.preference.PreferenceManager;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
 import android.webkit.WebView;
 import android.widget.Toast;

 import com.example.android.networkusage.R;
 import com.example.android.networkusage.StackOverflowXmlParser.Entry;

 import org.xmlpull.v1.XmlPullParserException;

 import java.io.IOException;
 import java.io.InputStream;
 import java.net.HttpURLConnection;
 import java.net.URL;
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.util.Calendar;
 import java.util.List;


 /**
  * Main Activity for the sample application.
  *
  * This activity does the following:
  *
  * o Presents a WebView screen to users. This WebView has a list of HTML links to the latest
  *   questions tagged 'android' on stackoverflow.com.
  *
  * o Parses the StackOverflow XML feed using XMLPullParser.
  *
  * o Uses AsyncTask to download and process the XML feed.
  *
  * o Monitors preferences and the device's network connection to determine whether
  *   to refresh the WebView content.
  */
 public class NetworkActivity extends Activity {
     public static final String WIFI = "Wi-Fi";
     public static final String ANY = "Any";
     private static final String URL =
             "http://stackoverflow.com/feeds/tag?tagnames=android&sort=newest";

     // Whether there is a Wi-Fi connection.
     private static boolean wifiConnected = false;
     // Whether there is a mobile connection.
     private static boolean mobileConnected = false;
     // Whether the display should be refreshed.
     public static boolean refreshDisplay = true;

     // The user's current network preference setting.
     public static String sPref = null;

     // The BroadcastReceiver that tracks network connectivity changes.
     private NetworkReceiver receiver = new NetworkReceiver();

     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

         // Register BroadcastReceiver to track connection changes.
         IntentFilter filter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
         receiver = new NetworkReceiver();
         this.registerReceiver(receiver, filter);
     }

     // Refreshes the display if the network connection and the
     // pref settings allow it.
     @Override
     public void onStart() {
         super.onStart();

         // Gets the user's network preference settings
         SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(this);

         // Retrieves a string value for the preferences. The second parameter
         // is the default value to use if a preference value is not found.
         sPref = sharedPrefs.getString("listPref", "Wi-Fi");

         updateConnectedFlags();

         // Only loads the page if refreshDisplay is true. Otherwise, keeps previous
         // display. For example, if the user has set "Wi-Fi only" in prefs and the
         // device loses its Wi-Fi connection midway through the user using the app,
         // you don't want to refresh the display--this would force the display of
         // an error page instead of stackoverflow.com content.
         if (refreshDisplay) {
             loadPage();
         }
     }

     @Override
     public void onDestroy() {
         super.onDestroy();
         if (receiver != null) {
             this.unregisterReceiver(receiver);
         }
     }

     // Checks the network connection and sets the wifiConnected and mobileConnected
     // variables accordingly.
     private void updateConnectedFlags() {
         ConnectivityManager connMgr =
                 (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

         NetworkInfo activeInfo = connMgr.getActiveNetworkInfo();
         if (activeInfo != null && activeInfo.isConnected()) {
             wifiConnected = activeInfo.getType() == ConnectivityManager.TYPE_WIFI;
             mobileConnected = activeInfo.getType() == ConnectivityManager.TYPE_MOBILE;
         } else {
             wifiConnected = false;
             mobileConnected = false;
         }
     }

     // Uses AsyncTask subclass to download the XML feed from stackoverflow.com.
     // This avoids UI lock up. To prevent network operations from
     // causing a delay that results in a poor user experience, always perform
     // network operations on a separate thread from the UI.
     private void loadPage() {
         if (((sPref.equals(ANY)) && (wifiConnected || mobileConnected))
                 || ((sPref.equals(WIFI)) && (wifiConnected))) {
             // AsyncTask subclass
             new DownloadXmlTask().execute(URL);
         } else {
             showErrorPage();
         }
     }

     // Displays an error if the app is unable to load content.
     private void showErrorPage() {
         setContentView(R.layout.main);

         // The specified network connection is not available. Displays error message.
         WebView myWebView = (WebView) findViewById(R.id.webview);
         myWebView.loadData(getResources().getString(R.string.connection_error),
                 "text/html", null);
     }

     // Populates the activity's options menu.
     @Override
     public boolean onCreateOptionsMenu(Menu menu) {
         MenuInflater inflater = getMenuInflater();
         inflater.inflate(R.menu.mainmenu, menu);
         return true;
     }

     // Handles the user's menu selection.
     @Override
     public boolean onOptionsItemSelected(MenuItem item) {
         switch (item.getItemId()) {
         case R.id.settings:
                 Intent settingsActivity = new Intent(getBaseContext(), SettingsActivity.class);
                 startActivity(settingsActivity);
                 return true;
         case R.id.refresh:
                 loadPage();
                 return true;
         default:
                 return super.onOptionsItemSelected(item);
         }
     }

     // Implementation of AsyncTask used to download XML feed from stackoverflow.com.
     private class DownloadXmlTask extends AsyncTask<String, Void, String> {

         @Override
         protected String doInBackground(String... urls) {
             try {
                 return loadXmlFromNetwork(urls[0]);
             } catch (IOException e) {
                 return getResources().getString(R.string.connection_error);
             } catch (XmlPullParserException e) {
                 return getResources().getString(R.string.xml_error);
             }
         }

         @Override
         protected void onPostExecute(String result) {
             setContentView(R.layout.main);
             // Displays the HTML string in the UI via a WebView
             WebView myWebView = (WebView) findViewById(R.id.webview);
             myWebView.loadData(result, "text/html", null);
         }
     }

     // Uploads XML from stackoverflow.com, parses it, and combines it with
     // HTML markup. Returns HTML string.
     private String loadXmlFromNetwork(String urlString) throws XmlPullParserException, IOException {
         InputStream stream = null;
         StackOverflowXmlParser stackOverflowXmlParser = new StackOverflowXmlParser();
         List<Entry> entries = null;
         String title = null;
         String url = null;
         String summary = null;
         Calendar rightNow = Calendar.getInstance();
         DateFormat formatter = new SimpleDateFormat("MMM dd h:mmaa");

         // Checks whether the user set the preference to include summary text
         SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(this);
         boolean pref = sharedPrefs.getBoolean("summaryPref", false);

         StringBuilder htmlString = new StringBuilder();
         htmlString.append("<h3>" + getResources().getString(R.string.page_title) + "</h3>");
         htmlString.append("<em>" + getResources().getString(R.string.updated) + " " +
                 formatter.format(rightNow.getTime()) + "</em>");

         try {
             stream = downloadUrl(urlString);
             entries = stackOverflowXmlParser.parse(stream);
         // Makes sure that the InputStream is closed after the app is
         // finished using it.
         } finally {
             if (stream != null) {
                 stream.close();
             }
         }

         // StackOverflowXmlParser returns a List (called "entries") of Entry objects.
         // Each Entry object represents a single post in the XML feed.
         // This section processes the entries list to combine each entry with HTML markup.
         // Each entry is displayed in the UI as a link that optionally includes
         // a text summary.
         for (Entry entry : entries) {
             htmlString.append("<p><a href='");
             htmlString.append(entry.link);
             htmlString.append("'>" + entry.title + "</a></p>");
             // If the user set the preference to include summary text,
             // adds it to the display.
             if (pref) {
                 htmlString.append(entry.summary);
             }
         }
         return htmlString.toString();
     }

     // Given a string representation of a URL, sets up a connection and gets
     // an input stream.
     private InputStream downloadUrl(String urlString) throws IOException {
         URL 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();
         return stream;
     }

     /**
      *
      * This BroadcastReceiver intercepts the android.net.ConnectivityManager.CONNECTIVITY_ACTION,
      * which indicates a connection change. It checks whether the type is TYPE_WIFI.
      * If it is, it checks whether Wi-Fi is connected and sets the wifiConnected flag in the
      * main activity accordingly.
      *
      */
     public class NetworkReceiver extends BroadcastReceiver {

         @Override
         public void onReceive(Context context, Intent intent) {
             ConnectivityManager connMgr =
                     (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
             NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();

             // Checks the user prefs and the network connection. Based on the result, decides
             // whether
             // to refresh the display or keep the current display.
             // If the userpref is Wi-Fi only, checks to see if the device has a Wi-Fi connection.
             if (WIFI.equals(sPref) && networkInfo != null
                     && networkInfo.getType() == ConnectivityManager.TYPE_WIFI) {
                 // If device has its Wi-Fi connection, sets refreshDisplay
                 // to true. This causes the display to be refreshed when the user
                 // returns to the app.
                 refreshDisplay = true;
                 Toast.makeText(context, R.string.wifi_connected, Toast.LENGTH_SHORT).show();

                 // If the setting is ANY network and there is a network connection
                 // (which by process of elimination would be mobile), sets refreshDisplay to true.
             } else if (ANY.equals(sPref) && networkInfo != null) {
                 refreshDisplay = true;

                 // Otherwise, the app can't download content--either because there is no network
                 // connection (mobile or Wi-Fi), or because the pref setting is WIFI, and there
                 // is no Wi-Fi connection.
                 // Sets refreshDisplay to false.
             } else {
                 refreshDisplay = false;
                 Toast.makeText(context, R.string.lost_connection, Toast.LENGTH_SHORT).show();
             }
         }
     }
 }
	/*
	* Copyright (C) 2012 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
	* in compliance with the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software distributed under the License
	* is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
	* or implied. See the License for the specific language governing permissions and limitations under
	* the License.
	*/

	package com.example.android.networkusage;

	import android.app.Activity;
	import android.content.BroadcastReceiver;
	import android.content.Context;
	import android.content.Intent;
	import android.content.IntentFilter;
	import android.content.SharedPreferences;
	import android.net.ConnectivityManager;
	import android.net.NetworkInfo;
	import android.os.AsyncTask;
	import android.os.Bundle;
	import android.preference.PreferenceManager;
	import android.view.Menu;
	import android.view.MenuInflater;
	import android.view.MenuItem;
	import android.webkit.WebView;
	import android.widget.Toast;

	import com.example.android.networkusage.R;
	import com.example.android.networkusage.StackOverflowXmlParser.Entry;

	import org.xmlpull.v1.XmlPullParserException;

	import java.io.IOException;
	import java.io.InputStream;
	import java.net.HttpURLConnection;
	import java.net.URL;
	import java.text.DateFormat;
	import java.text.SimpleDateFormat;
	import java.util.Calendar;
	import java.util.List;


	/**
	* Main Activity for the sample application.
	*
	* This activity does the following:
	*
	* o Presents a WebView screen to users. This WebView has a list of HTML links to the latest
	* questions tagged 'android' on stackoverflow.com.
	*
	* o Parses the StackOverflow XML feed using XMLPullParser.
	*
	* o Uses AsyncTask to download and process the XML feed.
	*
	* o Monitors preferences and the device's network connection to determine whether
	* to refresh the WebView content.
	*/
	public class NetworkActivity extends Activity {
	public static final String WIFI = "Wi-Fi";
	public static final String ANY = "Any";
	private static final String URL =
	"http://stackoverflow.com/feeds/tag?tagnames=android&sort=newest";

	// Whether there is a Wi-Fi connection.
	private static boolean wifiConnected = false;
	// Whether there is a mobile connection.
	private static boolean mobileConnected = false;
	// Whether the display should be refreshed.
	public static boolean refreshDisplay = true;

	// The user's current network preference setting.
	public static String sPref = null;

	// The BroadcastReceiver that tracks network connectivity changes.
	private NetworkReceiver receiver = new NetworkReceiver();

	@Override
	public void onCreate(Bundle savedInstanceState) {
	super.onCreate(savedInstanceState);

	// Register BroadcastReceiver to track connection changes.
	IntentFilter filter = new IntentFilter(ConnectivityManager.CONNECTIVITY_ACTION);
	receiver = new NetworkReceiver();
	this.registerReceiver(receiver, filter);
	}

	// Refreshes the display if the network connection and the
	// pref settings allow it.
	@Override
	public void onStart() {
	super.onStart();

	// Gets the user's network preference settings
	SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(this);

	// Retrieves a string value for the preferences. The second parameter
	// is the default value to use if a preference value is not found.
	sPref = sharedPrefs.getString("listPref", "Wi-Fi");

	updateConnectedFlags();

	// Only loads the page if refreshDisplay is true. Otherwise, keeps previous
	// display. For example, if the user has set "Wi-Fi only" in prefs and the
	// device loses its Wi-Fi connection midway through the user using the app,
	// you don't want to refresh the display--this would force the display of
	// an error page instead of stackoverflow.com content.
	if (refreshDisplay) {
	loadPage();
	}
	}

	@Override
	public void onDestroy() {
	super.onDestroy();
	if (receiver != null) {
	this.unregisterReceiver(receiver);
	}
	}

	// Checks the network connection and sets the wifiConnected and mobileConnected
	// variables accordingly.
	private void updateConnectedFlags() {
	ConnectivityManager connMgr =
	(ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);

	NetworkInfo activeInfo = connMgr.getActiveNetworkInfo();
	if (activeInfo != null && activeInfo.isConnected()) {
	wifiConnected = activeInfo.getType() == ConnectivityManager.TYPE_WIFI;
	mobileConnected = activeInfo.getType() == ConnectivityManager.TYPE_MOBILE;
	} else {
	wifiConnected = false;
	mobileConnected = false;
	}
	}

	// Uses AsyncTask subclass to download the XML feed from stackoverflow.com.
	// This avoids UI lock up. To prevent network operations from
	// causing a delay that results in a poor user experience, always perform
	// network operations on a separate thread from the UI.
	private void loadPage() {
	if (((sPref.equals(ANY)) && (wifiConnected \|\| mobileConnected))
	\|\| ((sPref.equals(WIFI)) && (wifiConnected))) {
	// AsyncTask subclass
	new DownloadXmlTask().execute(URL);
	} else {
	showErrorPage();
	}
	}

	// Displays an error if the app is unable to load content.
	private void showErrorPage() {
	setContentView(R.layout.main);

	// The specified network connection is not available. Displays error message.
	WebView myWebView = (WebView) findViewById(R.id.webview);
	myWebView.loadData(getResources().getString(R.string.connection_error),
	"text/html", null);
	}

	// Populates the activity's options menu.
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
	MenuInflater inflater = getMenuInflater();
	inflater.inflate(R.menu.mainmenu, menu);
	return true;
	}

	// Handles the user's menu selection.
	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
	switch (item.getItemId()) {
	case R.id.settings:
	Intent settingsActivity = new Intent(getBaseContext(), SettingsActivity.class);
	startActivity(settingsActivity);
	return true;
	case R.id.refresh:
	loadPage();
	return true;
	default:
	return super.onOptionsItemSelected(item);
	}
	}

	// Implementation of AsyncTask used to download XML feed from stackoverflow.com.
	private class DownloadXmlTask extends AsyncTask<String, Void, String> {

	@Override
	protected String doInBackground(String... urls) {
	try {
	return loadXmlFromNetwork(urls[0]);
	} catch (IOException e) {
	return getResources().getString(R.string.connection_error);
	} catch (XmlPullParserException e) {
	return getResources().getString(R.string.xml_error);
	}
	}

	@Override
	protected void onPostExecute(String result) {
	setContentView(R.layout.main);
	// Displays the HTML string in the UI via a WebView
	WebView myWebView = (WebView) findViewById(R.id.webview);
	myWebView.loadData(result, "text/html", null);
	}
	}

	// Uploads XML from stackoverflow.com, parses it, and combines it with
	// HTML markup. Returns HTML string.
	private String loadXmlFromNetwork(String urlString) throws XmlPullParserException, IOException {
	InputStream stream = null;
	StackOverflowXmlParser stackOverflowXmlParser = new StackOverflowXmlParser();
	List<Entry> entries = null;
	String title = null;
	String url = null;
	String summary = null;
	Calendar rightNow = Calendar.getInstance();
	DateFormat formatter = new SimpleDateFormat("MMM dd h:mmaa");

	// Checks whether the user set the preference to include summary text
	SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(this);
	boolean pref = sharedPrefs.getBoolean("summaryPref", false);

	StringBuilder htmlString = new StringBuilder();
	htmlString.append("<h3>" + getResources().getString(R.string.page_title) + "</h3>");
	htmlString.append("<em>" + getResources().getString(R.string.updated) + " " +
	formatter.format(rightNow.getTime()) + "</em>");

	try {
	stream = downloadUrl(urlString);
	entries = stackOverflowXmlParser.parse(stream);
	// Makes sure that the InputStream is closed after the app is
	// finished using it.
	} finally {
	if (stream != null) {
	stream.close();
	}
	}

	// StackOverflowXmlParser returns a List (called "entries") of Entry objects.
	// Each Entry object represents a single post in the XML feed.
	// This section processes the entries list to combine each entry with HTML markup.
	// Each entry is displayed in the UI as a link that optionally includes
	// a text summary.
	for (Entry entry : entries) {
	htmlString.append("<p><a href='");
	htmlString.append(entry.link);
	htmlString.append("'>" + entry.title + "</a></p>");
	// If the user set the preference to include summary text,
	// adds it to the display.
	if (pref) {
	htmlString.append(entry.summary);
	}
	}
	return htmlString.toString();
	}

	// Given a string representation of a URL, sets up a connection and gets
	// an input stream.
	private InputStream downloadUrl(String urlString) throws IOException {
	URL 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();
	return stream;
	}

	/**
	*
	* This BroadcastReceiver intercepts the android.net.ConnectivityManager.CONNECTIVITY_ACTION,
	* which indicates a connection change. It checks whether the type is TYPE_WIFI.
	* If it is, it checks whether Wi-Fi is connected and sets the wifiConnected flag in the
	* main activity accordingly.
	*
	*/
	public class NetworkReceiver extends BroadcastReceiver {

	@Override
	public void onReceive(Context context, Intent intent) {
	ConnectivityManager connMgr =
	(ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
	NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();

	// Checks the user prefs and the network connection. Based on the result, decides
	// whether
	// to refresh the display or keep the current display.
	// If the userpref is Wi-Fi only, checks to see if the device has a Wi-Fi connection.
	if (WIFI.equals(sPref) && networkInfo != null
	&& networkInfo.getType() == ConnectivityManager.TYPE_WIFI) {
	// If device has its Wi-Fi connection, sets refreshDisplay
	// to true. This causes the display to be refreshed when the user
	// returns to the app.
	refreshDisplay = true;
	Toast.makeText(context, R.string.wifi_connected, Toast.LENGTH_SHORT).show();

	// If the setting is ANY network and there is a network connection
	// (which by process of elimination would be mobile), sets refreshDisplay to true.
	} else if (ANY.equals(sPref) && networkInfo != null) {
	refreshDisplay = true;

	// Otherwise, the app can't download content--either because there is no network
	// connection (mobile or Wi-Fi), or because the pref setting is WIFI, and there
	// is no Wi-Fi connection.
	// Sets refreshDisplay to false.
	} else {
	refreshDisplay = false;
	Toast.makeText(context, R.string.lost_connection, Toast.LENGTH_SHORT).show();
	}
	}
	}
	}