PV239 #android2
cv3
Marek Sedlak
@msed__
PERMISSIONS
Permissions
● Each app operates in sandbox
● Additional capabilities? -> permissions in AndroidManifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.android.app.myapp" >
<uses-permission android:name="android.permission.RECEIVE_SMS" />
...
</manifest>
● More levels of protection
○ Normal permissions
■ resources outside the sandbox
■ little risk to the user’s privacy
○ Dangerous permissions
■ contacts
Marshmallow changes the flow (API23)
● App requests permission at run-time
if (ContextCompat.checkSelfPermission(thisActivity,
Manifest.permission.READ_CONTACTS)
!= PackageManager.PERMISSION_GRANTED) {
if (ActivityCompat.shouldShowRequestPermissionRationale(thisActivity,
Manifest.permission.READ_CONTACTS)) {
// show alert why we need that permisson
} else {
ActivityCompat.requestPermissions(thisActivity,
new String[]{Manifest.permission.READ_CONTACTS},
MY_PERMISSIONS_REQUEST_READ_CONTACTS);
// this means we have successfully requested the permission
}
}
STORAGE
STORAGE
● SharedPreferences
○ Simple values, String, Integer, Boolean,...
● Internal Storage, External Storage
○ External storage is World R/W
● SQLite DB
○ There are better approaches, like Realm
● Network
○ REST API, Custom server
SharedPreferences
● Simple Data
● public static final String PREFS_NAME = "MyPrefsFile";
● Writing
SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
SharedPreferences.Editor editor = settings.edit();
editor.putBoolean("silentMode", mSilentMode);
// Commit the edits!
editor.commit();
● Reading
SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0);
boolean silent = settings.getBoolean("silentMode", false);
setSilent(silent);
Internal Storage
● https://developer.android.com/guide/topics/data/data-storage.html#filesInternal
String FILENAME = "hello_file";
String string = "hello world!";
FileOutputStream fos = openFileOutput(FILENAME,
Context.MODE_PRIVATE);
fos.write(string.getBytes());
fos.close();
External Storage
● https://developer.android.com/guide/topics/data/data-storage.html#filesExterna
l
● External storage may be removed, replaced, erased by 3rd party
public File getAlbumStorageDir(String albumName) {
// Get the directory for the user's public pictures directory.
File file = new File(Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_PICTURES), albumName);
if (!file.mkdirs()) {
Log.e(LOG_TAG, "Directory not created");
}
return file;
}
● File based database
● There are better alternatives
● Better: Realm (try at home)
○ Has sync options (cross-platform/cloud)
SQLite
● JSON
● POST/PUT/GET Http methods
● Retrofit2
Network based storage
EXAMPLE
See git.
THANK YOU
See you on Slack.