public class SampleProvider extends ContentProvider
ContentProvider.PipeDataWriter<T>
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 |
---|
SampleProvider() |
Modifier and Type | Method and Description |
---|---|
int |
delete(Uri uri,
String selection,
String[] selectionArgs)
Implement this to handle requests to delete one or more rows.
|
String |
getType(Uri uri)
Implement this to handle requests for the MIME type of the data at the
given URI.
|
Uri |
insert(Uri uri,
ContentValues values)
Implement this to handle requests to insert a new row.
|
boolean |
onCreate()
Implement this to initialize your content provider on startup.
|
AssetFileDescriptor |
openAssetFile(Uri uri,
String mode)
This is like
ContentProvider.openFile(android.net.Uri, java.lang.String) , but can be implemented by providers
that need to be able to return sub-sections of files, often assets
inside of their .apk. |
Cursor |
query(Uri uri,
String[] projection,
String selection,
String[] selectionArgs,
String sortOrder)
Implement this to handle query requests from clients.
|
int |
update(Uri uri,
ContentValues values,
String selection,
String[] selectionArgs)
Implement this to handle requests to update one or more rows.
|
applyBatch, attachInfo, attachInfoForTesting, bulkInsert, call, canonicalize, coerceToLocalContentProvider, dump, enforceReadPermissionInner, enforceWritePermissionInner, getAppOpsManager, getAuthorityWithoutUserId, getCallingPackage, getContext, getIContentProvider, getPathPermissions, getReadPermission, getStreamTypes, getUriWithoutUserId, getUserIdFromAuthority, getUserIdFromAuthority, getUserIdFromUri, getUserIdFromUri, getWritePermission, isTemporary, matchesOurAuthorities, maybeAddUserId, onConfigurationChanged, onLowMemory, onTrimMemory, openAssetFile, openFile, openFile, openFileHelper, openPipeHelper, openTypedAssetFile, openTypedAssetFile, query, rejectInsert, setAppOps, setAuthorities, setPathPermissions, setReadPermission, setWritePermission, shutdown, uncanonicalize, uriHasUserId
public int delete(Uri uri, String selection, String[] selectionArgs)
ContentProvider
notifyChange()
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 ContentProvider
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.public String getType(Uri uri)
ContentProvider
vnd.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 ContentProvider
uri
- the URI to query.null
if there is no type.public Uri insert(Uri uri, ContentValues values)
ContentProvider
notifyChange()
after inserting.
This method can be called from multiple threads, as described in
Processes
and Threads.insert
in class ContentProvider
uri
- The content:// URI of the insertion request. This must not be null
.values
- A set of column_name/value pairs to add to the database.
This must not be null
.public boolean onCreate()
ContentProvider
You 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 ContentProvider
public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)
ContentProvider
Example 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 ContentProvider
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.null
.public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs)
ContentProvider
notifyChange()
after updating.
This method can be called from multiple threads, as described in
Processes
and Threads.update
in class ContentProvider
uri
- The URI to query. This can potentially have a record ID if this
is an update request for a specific record.values
- A set of column_name/value pairs to update in the database.
This must not be null
.selection
- An optional filter to match rows to update.public AssetFileDescriptor openAssetFile(Uri uri, String mode) throws FileNotFoundException
ContentProvider
ContentProvider.openFile(android.net.Uri, java.lang.String)
, but can be implemented by providers
that need to be able to return sub-sections of files, often assets
inside of their .apk.
This method can be called from multiple threads, as described in
Processes
and Threads.
If you implement this, your clients must be able to deal with such
file slices, either directly with
ContentResolver.openAssetFileDescriptor(android.net.Uri, java.lang.String)
, or by using the higher-level
ContentResolver.openInputStream
or ContentResolver.openOutputStream
methods.
The returned AssetFileDescriptor can be a pipe or socket pair to enable streaming of data.
If you are implementing this to return a full file, you
should create the AssetFileDescriptor with
AssetFileDescriptor.UNKNOWN_LENGTH
to be compatible with
applications that cannot handle sub-sections of files.
For use in Intents, you will want to implement ContentProvider.getType(android.net.Uri)
to return the appropriate MIME type for the data returned here with
the same URI. This will allow intent resolution to automatically determine the data MIME
type and select the appropriate matching targets as part of its operation.
For better interoperability with other applications, it is recommended
that for any URIs that can be opened, you also support queries on them
containing at least the columns specified by OpenableColumns
.
openAssetFile
in class ContentProvider
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.FileNotFoundException
- Throws FileNotFoundException if there is
no file associated with the given URI or the mode is invalid.ContentProvider.openFile(Uri, String)
,
ContentProvider.openFileHelper(Uri, String)
,
ContentProvider.getType(android.net.Uri)