CV3
Permissions
• API < 23 vs API >= 23
• AndroidManifest.xml
• Úroveň ochrany:
• Normal - vibrace, BT, internet - automatické
povolení systémem
• Dangerous - čtení sms, kontakty, poloha vyžaduje
interakci uživatele
Dangerous Permissions
Implementace
// Here, thisActivity is the current activity
if (ContextCompat.checkSelfPermission(thisActivity,
Manifest.permission.READ_CONTACTS)
!= PackageManager.PERMISSION_GRANTED) {
// Should we show an explanation?
if (ActivityCompat.shouldShowRequestPermissionRationale(thisActivity,
Manifest.permission.READ_CONTACTS)) {
// Show an explanation to the user *asynchronously* -- don't block
// this thread waiting for the user's response! After the user
// sees the explanation, try again to request the permission.
} else {
// No explanation needed, we can request the permission.
ActivityCompat.requestPermissions(thisActivity,
new String[]{Manifest.permission.READ_CONTACTS},
MY_PERMISSIONS_REQUEST_READ_CONTACTS);
// MY_PERMISSIONS_REQUEST_READ_CONTACTS is an
// app-defined int constant. The callback method gets the
// result of the request.
}
}
Storage
• SharedPreferences, Hawk
• Soubor
• Databaze
• ORM
SharedPreferences
• Jednoduchý key-value storage
• String, Boolean, Float, Int, Set<String>
• context.getSharedPreferences(“my”, 0)
https://developer.android.com/reference/android/content/
SharedPreferences.html
SharedPreferences
val sharedPrefs: SharedPreferences =
context.getSharedPreferences(“my”, 0)
sharedPrefs.getString(“name”, “”) // druhy param je default

sharedPrefs.getInt(“id”, 0)

sharedPrefs.contains(“name”) // true-false
val editor: SharedPreferences.Editor = sharedPrefs.edit()

editor.putString(“name”, “Radim”)

editor.commit(); // nebo editor.apply()
Zadání
• Vytvořte aplikaci, která bude zobrazovat
počet spuštění - číslo při každém
spuštění aplikace
Řešení
val sharedPrefs: SharedPreferences =
context.getSharedPreferences(“my”, 0)
val count = sharedPrefs.getInt(“count”, 0)
textview.text = String.valueOf(count)
sharedPrefs.edit().putInt(“count”, count + 1).apply();
Hawk
Hawk.init(context).build()
Hawk.put(key, T)
T value = Hawk.get(key)
Hawk.delete(key)
Hawk.contains(key)
compile 'com.orhanobut:hawk:2.0.1'
https://github.com/orhanobut/hawk
Soubor
• getFilesDir(), getCacheDir(),
getExternalFilesDir()
• android.permission.WRITE_EXTERNAL_STORAGE
• File - FileInputStream, FileOutputStream
Soubor - příklad
val filename: String = “hello_file"

val data: String = "hello world!"
val fos: FileOutputStream = 

openFileOutput(filename, Context.MODE_PRIVATE)

fos.write(data.bytes)

fos.close()
Database SQL
public class MySQLiteOpenHelper extends SQLiteOpenHelper {
public static final int DATABASE_VERSION = 1;
public static final String DATABASE_NAME = “MyDb.db";
public MySQLiteOpenHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
public void onCreate(SQLiteDatabase db) {
db.execSQL(SQL_CREATE_ENTRIES);
}
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL(SQL_DELETE_ENTRIES);
onCreate(db);
}
public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
onUpgrade(db, oldVersion, newVersion);
}
}
MySQLiteOpenHelper myDbHelper = new MySQLiteOpenHelper(getContext());
SQLiteDatabase db = myDbHelper.getReadableDatabase();

db.beginTransaction(); …
https://developer.android.com/training/basics/data-storage/databases.html
Room
Room - Entity
@Entity(tableName = "user")
data class Person(
@PrimaryKey
@ColumnInfo(name = "name")
var name: String = ""
)
Room - DAO
@Dao
interface PersonDao {
@Query("SELECT * FROM person")
fun findAll(): List<Person>
@Delete
fun remove(person: Person)
@Insert
fun insert(person: Person)
}
Room - AppDatabase
@Database(entities = arrayOf(Person::class), version = 1)
abstract class AppDatabase : RoomDatabase() {
abstract fun personDao(): PersonDao
}
Room - Použití
Room.databaseBuilder(this, AppDatabase::class.java, "db")
.allowMainThreadQueries()
.build()
db.personDao().insert(Person(“Radim”))
db.personDao().delete(Person(“Radim”))
db.personDao().findAll()