Boutsis Ioannis Programming for Android

Transcription

1 Boutsis Ioannis Programming for Android

2 History Android is developed by the Open Handset Alliance led by Google. Google purchased the initial developer of the software, Android Inc., in 2005.

3 Statistics

4 Architecture Applications All applications are written using the Java programming language. Application Framework By providing an open development platform, Android offers developers the ability to build extremely rich and innovative applications. Developers are free to take advantage of the device hardware, access location information, run background services, set alarms, add notifications to the status bar, and much, much more. Developers have full access to the same framework APIs used by the core applications. Libraries Android includes a set of C/C++ libraries used by various components of the Android system. These capabilities are exposed to developers through the Android application framework. Every Android application runs in its own process, with its own instance of the Dalvik virtual machine. Dalvik has been written so that a device can run multiple VMs efficiently. The Dalvik VM relies on the Linux kernel for underlying functionality such as threading and low-level memory management. Linux Kernel Android relies on Linux version 2.6 for core system services such as security, memory management, process management, network stack, and driver model. The kernel also acts as an abstraction layer between the hardware and the rest of the software stack.

5 Architecture

6 Components Activities are basically a graphical component and there should be a different activity for each UI screen of the application. Services are used as background tasks (e.g. playing music on the background) and they can be bind with a specific activity. Content Providers are used to manage access on persistent data that can be shared on different applications such as the contacts phone numbers. Broadcast Receivers are used to receive a notification and respond to that such as when receiving an SMS where the appropriate Activity should be invoked. Components communicate with messages called Intents, which are routed through Android runtime and the Kernel.

7 Programming... Android Manifest XML based User Interface Java Code

8 Android Manifest Every application must have an AndroidManifest.xml file (with precisely that name) in its root directory. The manifest presents essential information about the application to the Android system. Activities, Permissions, Minimum Android Level, etc. should be declared in the manifest. More Info:

9 AndroidManifest.xml <?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android=" package="com.test.android" android:versioncode="1" android:versionname="1.0" > <uses-sdk android:minsdkversion="8" /> /> <application > <activity android:name=".testandroidactivity" > <intent-filter > <action android:name="android.intent.action.main" /> <category android:name="android.intent.category.launcher" </intent-filter> </activity> <activity android:name=".activity2" > </activity> </application> </manifest>

10 Resources(/res) /drawables (low, medium, high) /layout (xml Uis) /values eg string.xml: <?xml version="1.0" encoding="utf-8"?> <resources> <string name="ds2011">distributed Systems</string> <string name="button_enter">enter</string> <string name="click_android">click on the android</string> <string name="changed_text">text to be changed</string> <string name="app_name">testandroid</string> </resources>

11 Layouts main.xml <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android=" apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:gravity="center" android:orientation="vertical" > <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:textsize="20sp" android:textstyle="bold" android:gravity="center_vertical center_horizontal"/> <ImageView android:layout_width="234dp" android:layout_height="246dp" /> <Button android:layout_width="150dp" android:layout_height="wrap_content" android:gravity="center_vertical center_horizontal" /> </LinearLayout>

12 Layouts activity2.xml <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android=" apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#330000" android:gravity="center" android:orientation="vertical" > <ImageView android:layout_width="180sp" android:layout_height="80sp" android:layout_marginbottom="50sp" /> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:gravity="center_vertical center_horizontal" android:textsize="16sp" android:textstyle="italic" /> <TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:gravity="center_vertical center_horizontal" android:background="#000066" android:textcolor="#ffcc00" android:typeface="monospace" /> </LinearLayout>

13 Java Code package com.test.android; import android.app.activity; import android.content.intent; import android.os.bundle; import android.view.view; import android.widget.button; TestAndroidActivity.java public class TestAndroidActivity extends Activity { /** Called when the activity is first created. public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.main); Button next = (Button) findviewbyid(r.id.button1); next.setonclicklistener(new View.OnClickListener() { public void onclick(view view) { Intent myintent = new Intent(view.getContext(), Activity2.class); startactivityforresult(myintent, 0); );

14 Java Code Activity2.java package com.test.android; import android.app.activity; import android.app.alertdialog; import android.content.dialoginterface; import android.os.bundle; import android.view.view; import android.widget.edittext; import android.widget.imageview; import android.widget.textview; import android.widget.toast; public class Activity2 extends Activity { private void androidclick() { final AlertDialog.Builder alert = new AlertDialog.Builder(this); final EditText input = new EditText(this); alert.setview(input); alert.setpositivebutton("change text", new DialogInterface.OnClickListener() { public void onclick(dialoginterface dialog, int whichbutton) { String value = input.gettext().tostring().trim(); changetext(value); ); /** Called when the activity is first created. */ public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); setcontentview(r.layout.activity2); final ImageView iv = (ImageView)findViewById(R.id.talking_android); // set the listener iv.setonclicklistener(new View.OnClickListener() { public void onclick(view view) { androidclick(); ); alert.setnegativebutton("cancel", new DialogInterface.OnClickListener() { public void onclick(dialoginterface dialog, int whichbutton) { dialog.cancel(); ); alert.show(); private void changetext(string value) { TextView tv = (TextView) findviewbyid(r.id.textview1); tv.settext(value); Toast.makeText(getApplicationContext(), "Text changed!", Toast.LENGTH_SHORT).show();

15 Java Code

16 Διευθυνσιοδότηση Στα κινητά οι διευθύνσεις ip δίνονται από το δίκτυο. Για όσους χρησιμοποιούν τον emulator οι διευθύνσεις ip που χρησιμοποιεί είναι διαφορετικές από αυτές του υπολογιστή working Έτσι, για να συνδεθεί ένας client στο ServerSocket του emulator πρέπει να γίνουν τα εξής: -το serversocket του emulator ανοίγει στο port που θέλουμε(έστω 5000) -Στη συνέχεια πρέπει να κάνουμε redirect κάποιο port σε αυτό. Ανοίγουμε ένα telnet στο port που τρέχει ο emulator(πχ 5554) με telnet localhost 5554 και εκτελούμε redir add tcp:5001:5000 -Τώρα κάθε client μπορεί να δημιουργήσει ένα socket για να συνδεθεί στο αρχικό serversocket με IP/port: :5001