public class MemoryFileProvider extends ContentProvider
ContentProvider.PipeDataWriter<T>| Modifier and Type | Field and Description |
|---|---|
static byte[] |
TEST_BLOB |
TRIM_MEMORY_BACKGROUND, TRIM_MEMORY_COMPLETE, TRIM_MEMORY_MODERATE, TRIM_MEMORY_RUNNING_CRITICAL, TRIM_MEMORY_RUNNING_LOW, TRIM_MEMORY_RUNNING_MODERATE, TRIM_MEMORY_UI_HIDDEN| Constructor and Description |
|---|
MemoryFileProvider() |
| Modifier and Type | Method and Description |
|---|---|
int |
delete(Uri url,
String where,
String[] whereArgs)
Implement this to handle requests to delete one or more rows.
|
String |
getType(Uri url)
Implement this to handle requests for the MIME type of the data at the
given URI.
|
Uri |
insert(Uri url,
ContentValues initialValues)
Implement this to handle requests to insert a new row.
|
boolean |
onCreate()
Implement this to initialize your content provider on startup.
|
ParcelFileDescriptor |
openFile(Uri url,
String mode)
Override this to handle requests to open a file blob.
|
Cursor |
query(Uri url,
String[] projectionIn,
String selection,
String[] selectionArgs,
String sort)
Implement this to handle query requests from clients.
|
int |
update(Uri url,
ContentValues values,
String where,
String[] whereArgs)
Implement this to handle requests to update one or more rows.
|
applyBatch, attachInfo, bulkInsert, call, coerceToLocalContentProvider, dump, getContext, getIContentProvider, getPathPermissions, getReadPermission, getStreamTypes, getWritePermission, isTemporary, onConfigurationChanged, onLowMemory, onTrimMemory, openAssetFile, openFileHelper, openPipeHelper, openTypedAssetFile, query, setPathPermissions, setReadPermission, setWritePermission, shutdownpublic boolean onCreate()
ContentProviderYou should defer nontrivial initialization (such as opening,
upgrading, and scanning databases) until the content provider is used
(via ContentProvider.query(android.net.Uri, java.lang.String[], java.lang.String, java.lang.String[], java.lang.String), ContentProvider.insert(android.net.Uri, android.content.ContentValues), etc). Deferred initialization
keeps application startup fast, avoids unnecessary work if the provider
turns out not to be needed, and stops database errors (such as a full
disk) from halting application launch.
If you use SQLite, SQLiteOpenHelper
is a helpful utility class that makes it easy to manage databases,
and will automatically defer opening until first use. If you do use
SQLiteOpenHelper, make sure to avoid calling
SQLiteOpenHelper.getReadableDatabase() or
SQLiteOpenHelper.getWritableDatabase()
from this method. (Instead, override
SQLiteOpenHelper.onOpen(android.database.sqlite.SQLiteDatabase) to initialize the
database when it is first opened.)
onCreate in class ContentProviderpublic Cursor query(Uri url, String[] projectionIn, String selection, String[] selectionArgs, String sort)
ContentProviderExample client call:
// Request a specific record.
Cursor managedCursor = managedQuery(
ContentUris.withAppendedId(Contacts.People.CONTENT_URI, 2),
projection, // Which columns to return.
null, // WHERE clause.
null, // WHERE clause value substitution
People.NAME + " ASC"); // Sort order.
Example implementation:
// SQLiteQueryBuilder is a helper class that creates the
// proper SQL syntax for us.
SQLiteQueryBuilder qBuilder = new SQLiteQueryBuilder();
// Set the table we're querying.
qBuilder.setTables(DATABASE_TABLE_NAME);
// If the query ends in a specific record number, we're
// being asked for a specific record, so set the
// WHERE clause in our query.
if((URI_MATCHER.match(uri)) == SPECIFIC_MESSAGE){
qBuilder.appendWhere("_id=" + uri.getPathLeafId());
}
// Make the query.
Cursor c = qBuilder.query(mDb,
projection,
selection,
selectionArgs,
groupBy,
having,
sortOrder);
c.setNotificationUri(getContext().getContentResolver(), uri);
return c;query in class ContentProviderurl - 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.projectionIn - 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.sort - How the rows in the cursor should be sorted.
If null then the provider is free to define the sort order.public String getType(Uri url)
ContentProvidervnd.android.cursor.item for a single record,
or vnd.android.cursor.dir/ for multiple items.
This method can be called from multiple threads, as described in
Processes
and Threads.
Note that there are no permissions needed for an application to access this information; if your content provider requires read and/or write permissions, or is not exported, all applications can still call this method regardless of their access permissions. This allows them to retrieve the MIME type for a URI when dispatching intents.
getType in class ContentProviderurl - the URI to query.public ParcelFileDescriptor openFile(Uri url, String mode) throws FileNotFoundException
ContentProviderFileNotFoundException.
This method can be called from multiple threads, as described in
Processes
and Threads.
This method returns a ParcelFileDescriptor, which is returned directly to the caller. This way large data (such as images and documents) can be returned without copying the content.
The returned ParcelFileDescriptor is owned by the caller, so it is their responsibility to close it when done. That is, the implementation of this method should create a new ParcelFileDescriptor for each call.
openFile in class ContentProviderurl - 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.FileNotFoundException - Throws FileNotFoundException if there is
no file associated with the given URI or the mode is invalid.ContentProvider.openAssetFile(Uri, String),
ContentProvider.openFileHelper(Uri, String)public int update(Uri url, ContentValues values, String where, String[] whereArgs)
ContentProvidernotifyChange()
after updating.
This method can be called from multiple threads, as described in
Processes
and Threads.update in class ContentProviderurl - 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).where - An optional filter to match rows to update.public Uri insert(Uri url, ContentValues initialValues)
ContentProvidernotifyChange()
after inserting.
This method can be called from multiple threads, as described in
Processes
and Threads.insert in class ContentProviderurl - The content:// URI of the insertion request.initialValues - A set of column_name/value pairs to add to the database.public int delete(Uri url, String where, String[] whereArgs)
ContentProvidernotifyDelete()
after deleting.
This method can be called from multiple threads, as described in
Processes
and Threads.
The implementation is responsible for parsing out a row ID at the end
of the URI, if a specific row is being deleted. That is, the client would
pass in content://contacts/people/22 and the implementation is
responsible for parsing the record number (22) when creating a SQL statement.
delete in class ContentProviderurl - The full URI to query, including a row ID (if a specific record is requested).where - An optional restriction to apply to rows when deleting.