android og persistens developer.android/guide/topics/data/data-storage.html
DESCRIPTION
Android og persistens http://developer.android.com/guide/topics/data/data-storage.html. Your data storage options are the following: Shared Preferences Store private primitive data in key-value pairs. Internal Storage Store private data on the device memory. - PowerPoint PPT PresentationTRANSCRIPT
Android og persistenshttp://developer.android.com/guide/topics/data/data-storage.html
• Your data storage options are the following:• Shared Preferences Store private primitive data in key-
value pairs. • Internal Storage Store private data on the device
memory. • External Storage Store public data on the shared
external storage. • SQLite Databases Store structured data in a private
database. • Network Connection Store data on the web with your
own network server.
SharedPreferences
Skriv til SharedPreferences
// We need an Editor object to make preference changes.// All objects are from android.context.Context•SharedPreferences settings = getSharedPreferences("MyPrefsFile", 0);•SharedPreferences.Editor editor = settings.edit();•editor.putBoolean("silentMode", mSilentMode);
Læs fra SharedPreferences
•SharedPreferences settings = getSharedPreferences("MyPrefsFile", 0);•boolean silent = settings.getBoolean("silentMode", false);•setSilent(silent);
Tekstfiler i Android (java)
Skriv på tekstfil•FileOutputStream outStream = openFileOutput("myfiletext",Context.MODE_PRIVATE); •PrintWriter outTextStream = new PrintWriter(outStream); •outTextStream.println("En tekst");•outTextStream.close();
Læs fra tekstfil•FileInputStream inFileStream = openFileInput("myfiletext"); •InputStreamReader inReader = new InputStreamReader(inFileStream); •BufferedReader buffReader = new BufferedReader(inReader); •String text;•text = (String) buffReader.readLine();•buffReader.close();
Serialisering af java-ObjekterFor at serialisere skal man implementere SerializableKlassen skal desuden forsynes med en unique ID
•import java.io.Serializable;
•public class BusinessModel implements Serializable {•private static final long serialVersionUID = -2255373015564100242L;•…………•}
Filer og java-Objekter
Skriv objekt til fil•FileOutputStream outFileStream = openFileOutput("myfileobjects”,Context.MODE_PRIVATE); •ObjectOutputStream outObjectStream = new ObjectOutputStream(outFileStream);•String simpleObject = "Hej "+(i+1); •outObjectStream.writeObject(simpleObject);•outTextStream.close();
Læs objekt fra fil•FileInputStream inStream = openFileInput("myfileobjects"); •ObjectInputStream inObjectStream = new ObjectInputStream(inStream); •String text;•String simpleObject;•simpleObject = (String) inObjectStream.readObject();•inObjectStream.close();
Check for exception EOFException
public directories on the external storage
• Music/ - Media scanner classifies all media found here as user music.
• Podcasts/ - Media scanner classifies all media found here as a podcast.
• Ringtones/ - Media scanner classifies all media found here as a ringtone.
• Alarms/ - Media scanner classifies all media found here as an alarm sound.
• Notifications/ - Media scanner classifies all media found here as a notification sound.
• Pictures/ - All photos (excluding those taken with the camera).
• Movies/ - All movies (excluding those taken with the camcorder).
• Download/ - Miscellaneous downloads.