com.ansca.corona.storage

Class FileContentProvider

java.lang.Object

android.content.ContentProvider

com.ansca.corona.storage.FileContentProvider

public class FileContentProvider
extends android.content.ContentProvider

This provider allows other applications read-only access to this application's files under its private directory under internal storage, as well as its asset files within the APK's "assets" directory or within Google Play expansion files. This class is needed because other applications do not have permission to access this application's private files for tasks such as attaching files to an e-mail, posting a photo to a social media app, playing a local video file on an external video player, etc.

In order for another application to access a file belonging to this application, you must create a "content://" URI which references that file by calling this class' createContentUriForFile() method. The other application will then use this content URI to communicate with this provider to retrieve information about that file and open an input stream to it.

If you do not want to expose your application's files to other applications, then you should set the provider's "exported" attribute to false in the "AndroidManifest.xml" file.

An instance of this class will be automatically created by the Android OS upon application startup. You should never create an instance of this class yourself.

Constructor Summary

Constructors

Constructor and Description
FileContentProvider()

Method Summary

Methods

Modifier and Type	Method and Description
static android.net.Uri	createContentUriForFile(android.content.Context context, File file) Creates a "content://" URI for the given file making it accessible to other applications via this provider.
static android.net.Uri	createContentUriForFile(android.content.Context context, String filePath) Creates a "content://" URI for the given file making it accessible to other applications via this provider.
int	delete(android.net.Uri uri, String selection, String[] selectionArgs) Handles a delete request from a client.
String	getType(android.net.Uri uri) Fetches the mime type of the file that the given URI references.
android.net.Uri	insert(android.net.Uri uri, android.content.ContentValues values) Handles an insert request from a client.
boolean	onCreate() Called on application startup if registered in the "AndroidManifest.xml" file.
android.content.res.AssetFileDescriptor	openAssetFile(android.net.Uri uri, String mode) Handles a client request to open a file belonging to this application via a file descriptor.
android.os.ParcelFileDescriptor	openFile(android.net.Uri uri, String mode) Handles a client request to open a file belonging to this application.
android.database.Cursor	query(android.net.Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) Handles query requests from clients.
int	update(android.net.Uri uri, android.content.ContentValues values, String selection, String[] selectionArgs) Handles an update request from a client.
static void	validateManifest(android.content.Context context) Checks if the AndroidManifest.xml file is correctly configured for this provider.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FileContentProvider

public FileContentProvider()

Method Detail

onCreate

public boolean onCreate()

Called on application startup if registered in the "AndroidManifest.xml" file. Initializes this object.

Returns:

Returns true if the provider was successfully loaded. Returns false if not.

openFile

public android.os.ParcelFileDescriptor openFile(android.net.Uri uri,
                                       String mode)
                                         throws FileNotFoundException

Handles a client request to open a file belonging to this application.

Parameters:

uri - The URI whose file is to be opened.

mode - Access mode for the file. May be "r" for read-only access, "rw" for read and write access, or "rwt" for read and write access that truncates any existing file.

Returns:

Returns a new ParcelFileDescriptor which you can use to access the file.

Throws:

FileNotFoundException

openAssetFile

public android.content.res.AssetFileDescriptor openAssetFile(android.net.Uri uri,
                                                    String mode)
                                                      throws FileNotFoundException

Handles a client request to open a file belonging to this application via a file descriptor.

Parameters:

uri - The URI whose file is to be opened.

mode - Access mode for the file. May be "r" for read-only access, "w" for write-only access (erasing whatever data is currently in the file), "wa" for write-only access to append to any existing data, "rw" for read and write access on any existing data, and "rwt" for read and write access that truncates any existing file.

Returns:

Returns a new AssetFileDescriptor which you can use to access the file.

Throws:

FileNotFoundException

delete

public int delete(android.net.Uri uri,
         String selection,
         String[] selectionArgs)

Handles a delete request from a client.

Not supported by this class. Calling this method will cause an exception to be thrown.

Parameters:

uri - The full URI to query, including a row ID (if a specific record is requested).

selection - An optional restriction to apply to rows when deleting.

Returns:

Returns the number of rows affected.

getType

public String getType(android.net.Uri uri)

Fetches the mime type of the file that the given URI references.

Parameters:

uri - The URI to query.

Returns:

Returns a MIME type string for the given URI.

Returns null if of an unknown type.

insert

public android.net.Uri insert(android.net.Uri uri,
                     android.content.ContentValues values)

Handles an insert request from a client.

Not supported by this class. Calling this method will cause an exception to be thrown.

Parameters:

uri - The content:// URI of the insertion request.

values - A set of column_name/value pairs to add to the database.

Returns:

Returns the URI for the newly inserted item.

query

public android.database.Cursor query(android.net.Uri uri,
                            String[] projection,
                            String selection,
                            String[] selectionArgs,
                            String sortOrder)

Handles query requests from clients.

Parameters:

uri - The URI to query. This will be the full URI sent by the client; if the client is requesting a specific record, the URI will end in a record number that the implementation should parse and add to a WHERE or HAVING clause, specifying that _id value.

projection - The list of columns to put into the cursor. If null all columns are included.

selection - A selection criteria to apply when filtering rows. If null then all rows are included.

selectionArgs - You may include ?s in selection, which will be replaced by the values from selectionArgs, in order that they appear in the selection. The values will be bound as Strings.

sortOrder - How the rows in the cursor should be sorted. If null then the provider is free to define the sort order.

Returns:

Returns a Cursor or null.

update

public int update(android.net.Uri uri,
         android.content.ContentValues values,
         String selection,
         String[] selectionArgs)

Handles an update request from a client. Not supported by this class. Calling this method will cause an exception to be thrown.

Parameters:

uri - The URI to query. This can potentially have a record ID if this is an update request for a specific record.

values - A Bundle mapping from column names to new column values (NULL is a valid value).

selection - An optional filter to match rows to update.

Returns:

Returns the number of rows affected.

validateManifest

public static void validateManifest(android.content.Context context)

Checks if the AndroidManifest.xml file is correctly configured for this provider.

Will throw an exception if the manifest is missing this provider or if its "authorities" attribute is misconfigured.

This method is only expected to be called by the CoronaActivity class.

Parameters:

context - Context needed to access this application's manifest settings. Cannot be null.

createContentUriForFile

public static android.net.Uri createContentUriForFile(android.content.Context context,
                                      File file)

Creates a "content://" URI for the given file making it accessible to other applications via this provider.

Parameters:

context - A reference to this application's context. Needed to fetch this application's package name. Cannot be null.

file - The file to create a content URI for.

If this file is set to a relative path, then this method will treat it as an asset file within the APK's "assets" directory or within the Google Play expansion file.

Cannot be null or else an exception will be thrown.

Returns:

Returns a matching "content://" URI for the given file.

createContentUriForFile

public static android.net.Uri createContentUriForFile(android.content.Context context,
                                      String filePath)

Creates a "content://" URI for the given file making it accessible to other applications via this provider.

Parameters:

context - A reference to this application's context. Needed to fetch this application's package name. Cannot be null.

filePath - A relative or absolute path to a file belonging to this application.

If this file is set to a relative path, then this method will treat it as an asset file within the APK's "assets" directory or within the Google Play expansion file.

An exception will be thrown if set to null or empty string.

Returns:

Returns a matching "content://" URI for the given file.