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
SharedPreferences sharedPrefs =
context.getSharedPreferences(“my”, 0);
sharedPrefs.getString(“name”, “”); // druhy param je default

sharedPrefs.getInt(“id”, 0);

sharedPrefs.contains(“name”); // true-false
SharedPreferences.Editor 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
SharedPreferences sharedPrefs =
context.getSharedPreferences(“my”, 0);
int count = sharedPrefs.getInt(“count”, 0);
textview.setText(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
String FILENAME = “hello_file";

String string = "hello world!";
FileOutputStream fos = openFileOutput(FILENAME, Context.MODE_PRIVATE);

fos.write(string.getBytes());

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
Realm
• ORM
• lazy-loaded
• Android (Java), iOS (Swift, Obj-C), Tamarin
https://realm.io
Realm - objekt
public class Dog extends RealmObject {
private String name;
private int age;
}
public class Person extends RealmObject {
@PrimaryKey
private long id;
private String name;
private RealmList<Dog> dogs;
}
Realm - inicializace
Realm.init(context);
// Get a Realm instance for this thread
Realm realm = Realm.getDefaultInstance();
Realm - insert
realm.beginTransaction();
User user = realm.createObject(User.class, primaryKey);
user.setName(“Radim”);
realm.commitTransaction();
User user = new User();
user.setName(“Radim");
realm.beginTransaction();
User realmUser = realm.copyToRealm(user);
realm.commitTransaction();
nebo
Realm - async
realm.executeTransactionAsync(new Realm.Transaction() {
@Override
public void execute(Realm r) {
User user = r.createObject(User.class);
user.setName("John");
user.setEmail("john@corporation.com");
}
}, new Realm.Transaction.OnSuccess() {
@Override
public void onSuccess() {
// Transaction was a success.
}
}, new Realm.Transaction.OnError() {
@Override
public void onError(Throwable error) {
// Transaction failed and was automatically canceled.
}
});
Realm - query
RealmResults<User> result = realm.where(User.class)
.findAll();
RealmResults<User> result = realm.where(User.class)
.equalTo("name", "John")
.or()
.equalTo("name", "Peter")
.findAll()
.sort(“age", Sort.DESCENDING);
Realm - delete
realm.where(User.class)
.findAll()
.deleteAllFromRealm();
Zadání
• Doplňte chybějící funkce Realmu pro přidání,
mazání a získání dat
Řešení
public void onClick(View view) {
realm.beginTransaction();
Todo user = realm.createObject(Todo.class, UUID.randomUUID().toString());
user.setName(input.getText().toString());
realm.commitTransaction();
}
RealmResults<Todo> todos = realm.where(Todo.class).findAll();
adapter = new TodoAdapter(todos);
Todo todo = adapter.getItem(i);
realm.beginTransaction();
realm.where(Todo.class)
.equalTo("uuid", todo.getUuid())
.findAll()
.deleteAllFromRealm();
realm.commitTransaction();