Android. Mobile Computing Design and Implementation. Application Components, Sensors. Peter Börjesson

Transcription

1 Android Application Components, Sensors Mobile Computing Design and Implementation Peter Börjesson

2 Application Sandbox Android System & Device Data Contacts, Messages, SD Card, Camera, Bluetooth, etc. Android Manifest Android Manifest Application A Application B Application ID Dalvik VM Process Application ID Dalvik VM Process

3 Application Components Activities Services Activated by Intents Broadcast Receivers Content Providers

4 Intents - Anatomy ComponentName Action Data Category Type Extras

5 Intents - ComponentName Class Name com.example.project.details.myactivitiy. Package Name (from Android Manifest) com.example.project Do not set this attribute unless you are absolutely sure about which component that should handle the intent. The system will decide for you. If this attribute is set, all other intent attributes become optional

6 Intents - Action and Data Action ACTION_VIEW, ACTION_DIAL, ACTION_EDIT Data (expressed as Uri) content://contacts/people/1 tel:123 Action and Data are the primary pieces of information in an intent.

7 Intents Category and Type Category CATEGORY_LAUNCHER CATEGORY_DEFAULT CATEGORY_BROWSABLE Type (MIME, usually inferred by the data itself) image/jpeg audio/mpeg text/html

8 Intents Extras Bundle intent.putextras(bundle); Bundle bundle = intent.getextras(); putextra & getextra intent.putextra( mytag1, 12); Intent.putExtra( mytag2, Peter ); int i = intent.getintextra( mytag1, -1); String s = intent.getstringextra( mytag );

9 Implicit intents Android System & Device Data Contacts, Messages, SD Card, Camera, Bluetooth, etc. Intent An application can have many entry points Camera Application Application Inbox Activity Read Mail Actitivity Compose Mail Activity

10 Implicit intents - Example Send SMS Send

11 Services Android System & Device Data Contacts, Messages, SD Card, Camera, Bluetooth, etc. Intent Play Music Service Music Player A service can run in the background, independent of activities

12 Services - Lifecycle

13 Services - Example Start Service Stop Service Android Manifest

14 Broadcast Receivers Android System & Device Data Contacts, Messages, SD Card, Camera, Bluetooth, etc. Intent Many Broadcasts originate from the system but can also be initiated by an application Application A Application A Application A

15 Broadcast Receivers - Example

16 Content Providers Android System & Device Data Contacts, Messages, SD Card, Camera, Bluetooth, etc. Contacts Browser CallLog MediaStore Settings Query content://contacts/people/2 Application Both the Android System and other applications can provide content.

17 Sensors

18 Sensors SensorManager Create an instance of the sensor service. Manage sensors sensor eventlisteners. Sensor Create an instance of a specific Senor SensorEvent Used by the system to provide information about a sensorevent SensorEventListener Interface to receive notification of sensor value and sensor accuracy changes

19 Sensors - SensorEventListener OnAccuracyChanged(Sensor sensor, int accuracy) Low, Medium, High, Unreliable OnSensorChanged(SensorEvent event) accuracy, sensor, timestamp, values

20 Sensors

21 Sensors Tips Don t test on the emulator Don't block the onsensorchanged() method Filter or reduce data outside of this method Avoid using deprecated methods or sensor types Verify sensors before you use them Choose sensor delays carefully Unregister sensor when not needed anymore