Content providers in Android

1. Content Providers in Android

2. ●
Overall structure
●
Interaction with Content Provider
●
Constructing query
●
Retreiving cursor asyncronuously
●
Provider permissions
●
Creating Content Provider
●
Questions

3. ●
Overall structure
●
Interaction with Content Provider
●
Constructing query
●
Retreiving cursor asyncronuously
●
Provider permissions
●
Creating Content Provider
●
Questions

4. Overall structure
Content Provider
Application #1
Activity #1
Activity #2
Activity #3
Database Files XML
Remote
connection
…
Activity #1
Application #2
Activity #1
Application #3
Activity #2

5. Content Provider is a source
Content Provider
Application #1
Activity #1
Activity #2
Activity #3
Database Files XML
Remote
connection
…
Activity #1
Application #2
Activity #1
Application #3
Activity #2

6. For some consumers
Content Provider
Application #1
Activity #1
Activity #2
Activity #3
Database Files XML
Remote
connection
…
Activity #1
Application #2
Activity #1
Application #3
Activity #2

7. Gives access to variety types of data
Content Provider
Application #1
Activity #1
Activity #2
Activity #3
Database Files XML
Remote
connection
…
Activity #1
Application #2
Activity #1
Application #3
Activity #2

8. Overall structure
Content Provider
Application #1
Activity #1
Activity #2
Activity #3
Database Files XML
Remote
connection
…
Activity #1
Application #2
Activity #1
Application #3
Activity #2

9. ●
Overall structure
●
Interaction with Content Provider
●
Constructing query
●
Retreiving cursor asyncronuously
●
Provider permissions
●
Creating Content Provider
●
Questions

10. Interaction with Content Provider
Content Provider
Application #1
Activity #1
Activity #2
Activity #3
Database Files XML
Remote
connection
…
Activity #1
Application #2
Activity #1
Application #3
Activity #2

11. Activity to Content Provider access
Content Provider
Activity
ContentResolverCursor
CursorAdapter ListView

12. Activity
Content Provider
Activity
ContentResolverCursor
CursorAdapter ListView

13. Performing request
ContentResolver
Query
Delete
Update
Insert
Content Provider
URI

14. URI
content://com.example.provider/articles
Scheme
Authority Path

15. ●
Overall structure
●
Interaction with Content Provider
●
Constructing query
●
Retreiving cursor asyncronuously
●
Provider permissions
●
Creating Content Provider
●
Questions

16. Constructing query
SELECT _id, title, content, date
FROM articles
WHERE date >= 1352470000
ORDER BY date ASC

17. Constructing query
String[] mProjection =
{
"_id",
"title",
"content",
"date",
};
String mSelection = "date >= ?";
String[] mSelectionArgs = { "1352470000"};
String mSortOrder = "date ASC";
Cursor cursor = getContentResolver().query(
MyContentProvider.ARTICLES_CONTENT_URI ,
mProjection,
mSelection,
mSelectionArgs,
mSortOrder);

18. Constructing query
String[] mProjection =
{
"_id",
"title",
"content",
"date",
};
String mSelection = "date >= ?";
String[] mSelectionArgs = {"1352470000"};
String mSortOrder = "date ASC";
Cursor cursor = getContentResolver().query(
MyContentProvider.ARTICLES_CONTENT_URI ,
mProjection,
mSelection,
mSelectionArgs,
mSortOrder);

19. Constructing query
String[] mProjection =
{
"_id",
"title",
"content",
"date",
};
String mSelection = "date >= ?";
String[] mSelectionArgs = { "1352470000"};
String mSortOrder = "date ASC";
Cursor cursor = getContentResolver().query(
MyContentProvider.ARTICLES_CONTENT_URI ,
mProjection,
mSelection,
mSelectionArgs,
mSortOrder);

20. Constructing query
String[] mProjection =
{
"_id",
"title",
"content",
"date",
};
String mSelection = "date >= ?";
String[] mSelectionArgs = {"1352470000"};
String mSortOrder = "date ASC";
Cursor cursor = getContentResolver().query(
MyContentProvider.ARTICLES_CONTENT_URI ,
mProjection,
mSelection,
mSelectionArgs,
mSortOrder);

21. Constructing query
String[] mProjection =
{
"_id",
"title",
"content",
"date",
};
String mSelection = "date >= ?";
String[] mSelectionArgs = {"1352470000"};
String mSortOrder = "date ASC";
Cursor cursor = getContentResolver().query (
MyContentProvider.ARTICLES_CONTENT_URI ,
mProjection,
mSelection,
mSelectionArgs,
mSortOrder);

22. Constructing query
String[] mProjection =
{
"_id",
"title",
"content",
"date",
};
String mSelection = "date >= ?";
String[] mSelectionArgs = {"1352470000"};
String mSortOrder = "date ASC";
Cursor cursor = getContentResolver().query(
MyContentProvider.ARTICLES_CONTENT_URI ,
mProjection,
mSelection,
mSelectionArgs,
mSortOrder);

23. Cursor
_id title content date
1 First article Lorem ipsum... 1352475013
2 Second article Dolor sit amet... 1352471413
... ... ... ...
if (mCursor != null) {
while (mCursor.moveToNext()) {
String title = mCursor.getString(Columns.TITLE);
}
}

24. ●
Overall structure
●
Interaction with Content Provider
●
Constructing query
●
Retreiving cursor asyncronuously
●
Provider permissions
●
Creating Content Provider
●
Questions

25. Activity & blocking queries
Content Provider
Activity
ContentResolverCursor
CursorAdapter ListView

26. Activity & non blocking queries
Content Provider
Activity
ContentResolverCursor
CursorAdapter ListView
CursorLoader
AsyncQueryHandler

27. Activity & Loader
Content Provider
Activity
ContentResolverCursor
CursorAdapter ListView
CursorLoader
AsyncQueryHandler

28. Activity & Loader
getSupportLoaderManager().initLoader(0, null, this);
...
public class ArticlesActivity extends FragmentActivity implements
LoaderCallbacks<Cursor> {
...
public Loader<Cursor> onCreateLoader( int id, Bundle args) {
return new CursorLoader(
this, // context
MyContentProvider.ARTICLES_CONTENT_URI ,
mProjection,
mSelection,
mSelectionArgs,
mSortOrder);
}
public void onLoadFinished(
Loader<Cursor> loader,
Cursor cursor) {
mAdapter.swapCursor(cursor);
}

29. Activity & Loader
getSupportLoaderManager().initLoader(0, null, this);
...
public class ArticlesActivity extends FragmentActivity implements
LoaderCallbacks<Cursor> {
...
public Loader<Cursor> onCreateLoader( int id, Bundle args) {
return new CursorLoader(
this, // context
MyContentProvider.ARTICLES_CONTENT_URI ,
mProjection,
mSelection,
mSelectionArgs,
mSortOrder);
}
public void onLoadFinished(
Loader<Cursor> loader,
Cursor cursor) {
mAdapter.swapCursor(cursor);
}

30. Activity & Loader
getSupportLoaderManager().initLoader(0, null, this);
...
public class ArticlesActivity extends FragmentActivity implements
LoaderCallbacks<Cursor> {
...
public Loader<Cursor> onCreateLoader( int id, Bundle args) {
return new CursorLoader(
this, // context
MyContentProvider.ARTICLES_CONTENT_URI ,
mProjection,
mSelection,
mSelectionArgs,
mSortOrder);
}
public void onLoadFinished(
Loader<Cursor> loader,
Cursor cursor) {
mAdapter.swapCursor(cursor);
}

31. Activity & Loader
getSupportLoaderManager().initLoader(0, null, this);
...
public class ArticlesActivity extends FragmentActivity implements
LoaderCallbacks<Cursor> {
...
public Loader<Cursor> onCreateLoader( int id, Bundle args) {
return new CursorLoader(
this, // context
MyContentProvider.ARTICLES_CONTENT_URI ,
mProjection,
mSelection,
mSelectionArgs,
mSortOrder);
}
public void onLoadFinished(
Loader<Cursor> loader,
Cursor cursor) {
mAdapter.swapCursor(cursor);
}

32. Activity & Loader
getSupportLoaderManager().initLoader(0, null, this);
...
public class ArticlesActivity extends FragmentActivity implements
LoaderCallbacks<Cursor> {
...
public Loader<Cursor> onCreateLoader( int id, Bundle args) {
return new CursorLoader(
this, // context
MyContentProvider.ARTICLES_CONTENT_URI ,
mProjection,
mSelection,
mSelectionArgs,
mSortOrder);
}
public void onLoadFinished(
Loader<Cursor> loader,
Cursor cursor) {
mAdapter.swapCursor(cursor);
}

33. Activity & AsyncQueryHandler
Content Provider
Activity
ContentResolverCursor
CursorAdapter ListView
CursorLoader
AsyncQueryHandler

34. Activity & AsyncQueryHandler
private AsyncQueryHandler mHandler;
...
mHandler = new MyAsyncQueryHandler(getContentResolver());
mHandler.startQuery(
0, // token
null, // cookie
MyContentProvider.ARTICLES_CONTENT_URI ,
mProjection,
mSelection,
mSelectionArgs,
mSortOrder);

35. Activity & AsyncQueryHandler
class MyAsyncQueryHandler extends AsyncQueryHandler {
public MyAsyncQueryHandler(ContentResolver cr) {
super(cr);
}

@Override
protected void onQueryComplete(
int token,
Object cookie,
Cursor cursor) {
mAdapter.swapCursor(cursor);
}
}

36. ●
Overall structure
●
Interaction with Content Provider
●
Constructing query
●
Retreiving cursor asyncronuously
●
Provider permissions
●
Creating Content Provider
●
Questions

37. Permissions
<permission
android:name="com.example.provider.permission.READ_ARTICLES"
android:protectionLevel ="normal" />
<provider android:name= ".MyContentProvider"
android:exported="false"
android:authorities= "com.example.provider"
android:permission="com.example.provider.permission.READ_ARTICLES"
/>
<uses-permission
android:name="com.example.provider.permission.READ_ARTICLES" />

38. Permissions
<permission
android:name="com.example.provider.permission.READ_ARTICLES"
android:protectionLevel= "normal" />
<provider android:name=".MyContentProvider"
android:exported="false"
android:authorities="com.example.provider"
android:permission="com.example.provider.permission.READ_ARTICLES"
/>
<uses-permission
android:name="com.example.provider.permission.READ_ARTICLES" />

39. Permissions
<permission
android:name="com.example.provider.permission.READ_ARTICLES"
android:protectionLevel= "normal" />
<provider android:name= ".MyContentProvider"
android:exported="false"
android:authorities= "com.example.provider"
android:permission="com.example.provider.permission.READ_ARTICLES"
/>
<uses-permission
android:name="com.example.provider.permission.READ_ARTICLES" />

40. ●
Overall structure
●
Interaction with Content Provider
●
Constructing query
●
Retreiving cursor asyncronuously
●
Provider permissions
●
Creating Content Provider
●
Questions

41. Creating content provider
public class MyContentProvider extends ContentProvider {
...
onCreate()
query()
insert()
update()
delete()
getType()

42. URI matching
content://com.example.provider/articles
content://com.example.provider/articles/*
content://com.example.provider/articles/#

43. URI matching
content://com.example.provider/articles
content://com.example.provider/articles/*
content://com.example.provider/articles/#

44. URI matching
content://com.example.provider/articles
content://com.example.provider/articles/*
content://com.example.provider/articles/#

45. URI matching
sUriMatcher.addURI("com.example.provider" , "articles/#", 0);
sUriMatcher.addURI("com.example.provider" , "articles/today", 1);
sUriMatcher.addURI("com.example.provider" , "articles/history/*" , 2);
...
public String getType(Uri uri) {
switch (sUriMatcher.match(uri)) {
...

46. URI matching
sUriMatcher.addURI("com.example.provider", "articles/#", 0);
sUriMatcher.addURI("com.example.provider", "articles/today", 1);
sUriMatcher.addURI("com.example.provider", "articles/history/*", 2);
...
public String getType(Uri uri) {
switch (sUriMatcher.match(uri)) {
...

47. MIME types
vnd.android.cursor.dir/vnd.com.example.provider .article
vnd.android.cursor.item/vnd.com.example.provider .article
getType()
getStreamTypes()
{ "image/jpeg", "image/png", "image/gif" }

48. MIME types
vnd.android.cursor.dir/vnd.com.example.provider.article
vnd.android.cursor.item/vnd.com.example.provider.article
getType()
getStreamTypes()
{ "image/jpeg", "image/png", "image/gif" }

49. Questions
Thank you!

50. Useful links
http://developer.android.com/guide/topics/providers/content-provider-basics.html
http://developer.android.com/guide/topics/providers/content-provider-creating.html
http://developer.android.com/guide/topics/security/permissions.html
http://gdg.org.ua
http://dnipro.gdg.org.ua

51. About speaker
Alexey Ustenko — Android developer
Coordniator of GDG Dnipropetrovs'k
@ustav