Content providers in Android

Content Providers in Android

● Overall structure

● Interaction with Content Provider● Constructing query● Retreiving cursor asyncronuously● Provider permissions● Creating Content Provider● Questions

● Overall structure

● Interaction with Content Provider● Constructing query● Retreiving cursor asyncronuously● Provider permissions● Creating Content Provider● Questions

Overall structure

Content Provider

Application #1

Activity #1

Activity #2

Activity #3

Database Files XML Remoteconnection …

Activity #1

Application #2

Activity #1

Application #3

Activity #2

Content Provider is a source

Content Provider

Application #1

Activity #1

Activity #2

Activity #3

Database Files XML Remoteconnection …

Activity #1

Application #2

Activity #1

Application #3

Activity #2

For some consumers

Content Provider

Application #1

Activity #1

Activity #2

Activity #3

Database Files XML Remoteconnection …

Activity #1

Application #2

Activity #1

Application #3

Activity #2

Gives access to variety types of data

Content Provider

Application #1

Activity #1

Activity #2

Activity #3

Database Files XML Remoteconnection …

Activity #1

Application #2

Activity #1

Application #3

Activity #2

Overall structure

Content Provider

Application #1

Activity #1

Activity #2

Activity #3

Database Files XML Remoteconnection …

Activity #1

Application #2

Activity #1

Application #3

Activity #2

● Overall structure

● Interaction with Content Provider● Constructing query● Retreiving cursor asyncronuously● Provider permissions● Creating Content Provider● Questions

Interaction with Content Provider

Content Provider

Application #1

Activity #1

Activity #2

Activity #3

Database Files XML Remoteconnection …

Activity #1

Application #2

Activity #1

Application #3

Activity #2

Activity to Content Provider access

Content Provider

Activity

ContentResolverCursor

CursorAdapter ListView

Activity

Content Provider

Activity

ContentResolverCursor

CursorAdapter ListView

Performing request

ContentResolver

Query

Delete

Update

Insert

Content Provider

URI

URI

content://com.example.provider/articles

Scheme Authority Path

● Overall structure

● Interaction with Content Provider● Constructing query● Retreiving cursor asyncronuously● Provider permissions● Creating Content Provider● Questions

Constructing query

SELECT _id, title, content, date FROM articles WHERE date >= 1352470000 ORDER BY date ASC

Constructing queryString[] 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);

Constructing queryString[] 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);

Constructing queryString[] 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);

Constructing queryString[] 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);

Constructing queryString[] 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);

Constructing queryString[] 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);

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); }}

● Overall structure

● Interaction with Content Provider● Constructing query● Retreiving cursor asyncronuously● Provider permissions● Creating Content Provider● Questions

Activity & blocking queries

Content Provider

Activity

ContentResolverCursor

CursorAdapter ListView

Activity & non blocking queries

Content Provider

Activity

ContentResolverCursor

CursorAdapter ListView

CursorLoader

AsyncQueryHandler

Activity & Loader

Content Provider

Activity

ContentResolverCursor

CursorAdapter ListView

CursorLoader

AsyncQueryHandler

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); }

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); }

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); }

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); }

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); }

Activity & AsyncQueryHandler

Content Provider

Activity

ContentResolverCursor

CursorAdapter ListView

CursorLoader

AsyncQueryHandler

Activity & AsyncQueryHandler

private AsyncQueryHandler mHandler;

...

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

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); } }

● Overall structure

● Interaction with Content Provider● Constructing query● Retreiving cursor asyncronuously● Provider permissions● Creating Content Provider● Questions

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" />

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" />

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" />

● Overall structure

● Interaction with Content Provider● Constructing query● Retreiving cursor asyncronuously● Provider permissions● Creating Content Provider● Questions

Creating content provider

public class MyContentProvider extends ContentProvider {...

onCreate()

query()

insert()

update()

delete()

getType()

URI matching

content://com.example.provider/articles

content://com.example.provider/articles/*

content://com.example.provider/articles/#

URI matching

content://com.example.provider/articles

content://com.example.provider/articles/*

content://com.example.provider/articles/#

URI matching

content://com.example.provider/articles

content://com.example.provider/articles/*

content://com.example.provider/articles/#

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)) {...

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)) {...

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" }

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" }

Questions

Thank you!

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

About speaker

Alexey Ustenko — Android developerCoordniator of GDG Dnipropetrovs'k

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