ContentProvider
public
abstract
class
ContentProvider
extends Object
implements
ComponentCallbacks2
java.lang.Object | |
↳ | android.content.ContentProvider |
Content providers are one of the primary building blocks of Android applications, providing
content to applications. They encapsulate data and provide it to applications through the single
ContentResolver
interface. A content provider is only required if you need to share
data between multiple applications. For example, the contacts data is used by multiple
applications and must be stored in a content provider. If you don't need to share data amongst
multiple applications you can use a database directly via
SQLiteDatabase
.
When a request is made via
a ContentResolver
the system inspects the authority of the given URI and passes the
request to the content provider registered with the authority. The content provider can interpret
the rest of the URI however it wants. The UriMatcher
class is helpful for parsing
URIs.
The primary methods that need to be implemented are:
onCreate()
which is called to initialize the providerquery(Uri, String, Bundle, CancellationSignal)
which returns data to the callerinsert(Uri, ContentValues)
which inserts new data into the content providerupdate(Uri, ContentValues, Bundle)
which updates existing data in the content providerdelete(Uri, Bundle)
which deletes data from the content providergetType(Uri)
which returns the MIME type of data in the content provider
Data access methods (such as insert(Uri, ContentValues)
and
update(Uri, ContentValues, Bundle)
) may be called from many threads at once, and must be thread-safe.
Other methods (such as onCreate()
) are only called from the application
main thread, and must avoid performing lengthy operations. See the method
descriptions for their expected thread behavior.
Requests to ContentResolver
are automatically forwarded to the appropriate
ContentProvider instance, so subclasses don't have to worry about the details of
cross-process calls.
Developer Guides
For more information about using content providers, read the Content Providers developer guide.
Summary
Nested classes | |
---|---|
class |
ContentProvider.CallingIdentity
Opaque token representing the identity of an incoming IPC. |
interface |
ContentProvider.PipeDataWriter<T>
Interface to write a stream of data to a pipe. |
Inherited constants |
---|
Public constructors | |
---|---|
ContentProvider()
Construct a ContentProvider instance. |
Public methods | |
---|---|
ContentProviderResult[]
|
applyBatch(String authority, ArrayList<ContentProviderOperation> operations)
Override this to handle requests to perform a batch of operations, or the
default implementation will iterate over the operations and call
|
ContentProviderResult[]
|
applyBatch(ArrayList<ContentProviderOperation> operations)
|
void
|
attachInfo(Context context, ProviderInfo info)
After being instantiated, this is called to tell the content provider about itself. |
int
|
bulkInsert(Uri uri, ContentValues[] values)
Override this to handle requests to insert a set of new rows, or the
default implementation will iterate over the values and call
|
Bundle
|
call(String authority, String method, String arg, Bundle extras)
Call a provider-defined method. |
Bundle
|
call(String method, String arg, Bundle extras)
|
Uri
|
canonicalize(Uri url)
Implement this to support canonicalization of URIs that refer to your content provider. |
final
ContentProvider.CallingIdentity
|
clearCallingIdentity()
Reset the identity of the incoming IPC on the current thread. |
abstract
int
|
delete(Uri uri, String selection, String[] selectionArgs)
Implement this to handle requests to delete one or more rows. |
int
|
delete(Uri uri, Bundle extras)
Implement this to handle requests to delete one or more rows. |
void
|
dump(FileDescriptor fd, PrintWriter writer, String[] args)
Print the Provider's state into the given stream. |
final
AttributionSource
|
getCallingAttributionSource()
Gets the attribution source of the calling app. |
final
String
|
getCallingAttributionTag()
Return the attribution tag of the caller that initiated the request being processed on the current thread. |
final
String
|
getCallingPackage()
Return the package name of the caller that initiated the request being processed on the current thread. |
final
String
|
getCallingPackageUnchecked()
Return the package name of the caller that initiated the request being processed on the current thread. |
final
Context
|
getContext()
Retrieves the Context this provider is running in. |
final
PathPermission[]
|
getPathPermissions()
Return the path-based permissions required for read and/or write access to this content provider. |
final
String
|
getReadPermission()
Return the name of the permission required for read-only access to this content provider. |
String[]
|
getStreamTypes(Uri uri, String mimeTypeFilter)
Called by a client to determine the types of data streams that this content provider supports for the given URI. |
abstract
String
|
getType(Uri uri)
Implement this to handle requests for the MIME type of the data at the given URI. |
String
|
getTypeAnonymous(Uri uri)
Implement this to handle requests for MIME type of URIs, that does not need to reveal any internal information which should be protected by any permission. |
final
String
|
getWritePermission()
Return the name of the permission required for read/write access to this content provider. |
Uri
|
insert(Uri uri, ContentValues values, Bundle extras)
Implement this to handle requests to insert a new row. |
abstract
Uri
|
insert(Uri uri, ContentValues values)
Implement this to handle requests to insert a new row. |
void
|
onCallingPackageChanged()
Called whenever the value of |
void
|
onConfigurationChanged(Configuration newConfig)
Called by the system when the device configuration changes while your component is running. This method is always called on the application main thread, and must not perform lengthy operations. |
abstract
boolean
|
onCreate()
Implement this to initialize your content provider on startup. |
void
|
onLowMemory()
This is called when the overall system is running low on memory, and actively running processes should trim their memory usage. This method is always called on the application main thread, and must not perform lengthy operations. |
void
|
onTrimMemory(int level)
Called when the operating system has determined that it is a good time for a process to trim unneeded memory from its process. |
AssetFileDescriptor
|
openAssetFile(Uri uri, String mode, CancellationSignal signal)
This is like |
AssetFileDescriptor
|
openAssetFile(Uri uri, String mode)
This is like |
ParcelFileDescriptor
|
openFile(Uri uri, String mode, CancellationSignal signal)
Override this to handle requests to open a file blob. |
ParcelFileDescriptor
|
openFile(Uri uri, String mode)
Override this to handle requests to open a file blob. |
<T>
ParcelFileDescriptor
|
openPipeHelper(Uri uri, String mimeType, Bundle opts, T args, PipeDataWriter<T> func)
A helper function for implementing |
AssetFileDescriptor
|
openTypedAssetFile(Uri uri, String mimeTypeFilter, Bundle opts, CancellationSignal signal)
Called by a client to open a read-only stream containing data of a particular MIME type. |
AssetFileDescriptor
|
openTypedAssetFile(Uri uri, String mimeTypeFilter, Bundle opts)
Called by a client to open a read-only stream containing data of a particular MIME type. |
Cursor
|
query(Uri uri, String[] projection, Bundle queryArgs, CancellationSignal cancellationSignal)
Implement this to handle query requests where the arguments are packed into a |
Cursor
|
query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder, CancellationSignal cancellationSignal)
Implement this to handle query requests from clients with support for cancellation. |
abstract
Cursor
|
query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)
Implement this to handle query requests from clients. |
boolean
|
refresh(Uri uri, Bundle extras, CancellationSignal cancellationSignal)
Implement this to support refresh of content identified by |
final
Context
|
requireContext()
Retrieves a Non-Nullable Context this provider is running in, this is intended to be called
after |
final
void
|
restoreCallingIdentity(ContentProvider.CallingIdentity identity)
Restore the identity of the incoming IPC on the current thread back to a
previously identity that was returned by |
void
|
shutdown()
Implement this to shut down the ContentProvider instance. |
Uri
|
uncanonicalize(Uri url)
Remove canonicalization from canonical URIs previously returned by
|
int
|
update(Uri uri, ContentValues values, Bundle extras)
Implement this to handle requests to update one or more rows. |
abstract
int
|
update(Uri uri, ContentValues values, String selection, String[] selectionArgs)
Implement this to handle requests to update one or more rows. |
Protected methods | |
---|---|
boolean
|
isTemporary()
Returns true if this instance is a temporary content provider. |
final
ParcelFileDescriptor
|
openFileHelper(Uri uri, String mode)
Convenience for subclasses that wish to implement |
final
void
|
setPathPermissions(PathPermission[] permissions)
Change the path-based permission required to read and/or write data in the content provider. |
final
void
|
setReadPermission(String permission)
Change the permission required to read data from the content provider. |
final
void
|
setWritePermission(String permission)
Change the permission required to read and write data in the content provider. |
Inherited methods | |
---|---|
Public constructors
ContentProvider
public ContentProvider ()
Construct a ContentProvider instance. Content providers must be
declared
in the manifest, accessed with ContentResolver
, and created
automatically by the system, so applications usually do not create
ContentProvider instances directly.
At construction time, the object is uninitialized, and most fields and
methods are unavailable. Subclasses should initialize themselves in
onCreate()
, not the constructor.
Content providers are created on the application main thread at application launch time. The constructor must not perform lengthy operations, or application startup will be delayed.
Public methods
applyBatch
public ContentProviderResult[] applyBatch (String authority, ArrayList<ContentProviderOperation> operations)
Override this to handle requests to perform a batch of operations, or the
default implementation will iterate over the operations and call
ContentProviderOperation#apply
on each of them.
If all calls to ContentProviderOperation#apply
succeed
then a ContentProviderResult
array with as many
elements as there were operations will be returned. If any of the calls
fail, it is up to the implementation how many of the others take effect.
This method can be called from multiple threads, as described in
Processes
and Threads.
Parameters | |
---|---|
authority |
String : This value cannot be null . |
operations |
ArrayList : the operations to apply
This value cannot be null . |
Returns | |
---|---|
ContentProviderResult[] |
the results of the applications
This value cannot be null . |
Throws | |
---|---|
OperationApplicationException |
thrown if any operation fails. |
applyBatch
public ContentProviderResult[] applyBatch (ArrayList<ContentProviderOperation> operations)
Parameters | |
---|---|
operations |
ArrayList : This value cannot be null . |
Returns | |
---|---|
ContentProviderResult[] |
This value cannot be null . |
Throws | |
---|---|
OperationApplicationException |
attachInfo
public void attachInfo (Context context, ProviderInfo info)
After being instantiated, this is called to tell the content provider about itself.
Parameters | |
---|---|
context |
Context : The context this provider is running in |
info |
ProviderInfo : Registered information about this content provider |
bulkInsert
public int bulkInsert (Uri uri, ContentValues[] values)
Override this to handle requests to insert a set of new rows, or the
default implementation will iterate over the values and call
insert(Uri, ContentValues)
on each of them.
As a courtesy, call notifyChange()
after inserting.
This method can be called from multiple threads, as described in
Processes
and Threads.
Parameters | |
---|---|
uri |
Uri : The content:// URI of the insertion request.
This value cannot be null . |
values |
ContentValues : An array of sets of column_name/value pairs to add to the database.
This must not be null . |
Returns | |
---|---|
int |
The number of values that were inserted. |
call
public Bundle call (String authority, String method, String arg, Bundle extras)
Call a provider-defined method. This can be used to implement interfaces that are cheaper and/or unnatural for a table-like model.
WARNING: The framework does no permission checking on this entry into the content provider besides the basic ability for the application to get access to the provider at all. For example, it has no idea whether the call being executed may read or write data in the provider, so can't enforce those individual permissions. Any implementation of this method must do its own permission checks on incoming calls to make sure they are allowed.
Parameters | |
---|---|
authority |
String : This value cannot be null . |
method |
String : method name to call. Opaque to framework, but should not be null . |
arg |
String : provider-defined String argument. May be null . |
extras |
Bundle : provider-defined Bundle argument. May be null . |
Returns | |
---|---|
Bundle |
provider-defined return value. May be null , which is also
the default for providers which don't implement any call methods. |
call
public Bundle call (String method, String arg, Bundle extras)
Parameters | |
---|---|
method |
String : This value cannot be null . |
arg |
String : This value may be null . |
extras |
Bundle : This value may be null . |
Returns | |
---|---|
Bundle |
This value may be null . |
canonicalize
public Uri canonicalize (Uri url)
Implement this to support canonicalization of URIs that refer to your content provider. A canonical URI is one that can be transported across devices, backup/restore, and other contexts, and still be able to refer to the same data item. Typically this is implemented by adding query params to the URI allowing the content provider to verify that an incoming canonical URI references the same data as it was originally intended for and, if it doesn't, to find that data (if it exists) in the current environment.
For example, if the content provider holds people and a normal URI in it is created with a row index into that people database, the cananical representation may have an additional query param at the end which specifies the name of the person it is intended for. Later calls into the provider with that URI will look up the row of that URI's base index and, if it doesn't match or its entry's name doesn't match the name in the query param, perform a query on its database to find the correct row to operate on.
If you implement support for canonical URIs, all incoming calls with
URIs (including this one) must perform this verification and recovery of any
canonical URIs they receive. In addition, you must also implement
uncanonicalize(Uri)
to strip the canonicalization of any of these URIs.
The default implementation of this method returns null, indicating that canonical URIs are not supported.
Parameters | |
---|---|
url |
Uri : The Uri to canonicalize.
This value cannot be null . |
Returns | |
---|---|
Uri |
Return the canonical representation of url, or null if canonicalization of that Uri is not supported. |
clearCallingIdentity
public final ContentProvider.CallingIdentity clearCallingIdentity ()
Reset the identity of the incoming IPC on the current thread.
Internally this calls Binder#clearCallingIdentity()
and also
clears any value stored in getCallingPackage()
.
Returns | |
---|---|
ContentProvider.CallingIdentity |
Returns an opaque token that can be used to restore the original
calling identity by passing it to
restoreCallingIdentity(CallingIdentity) .
This value cannot be null . |
delete
public abstract int delete (Uri uri, String selection, String[] selectionArgs)
Implement this to handle requests to delete one or more rows. The
implementation should apply the selection clause when performing
deletion, allowing the operation to affect multiple rows in a directory.
As a courtesy, call
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.
Parameters | |
---|---|
uri |
Uri : The full URI to query, including a row ID (if a specific
record is requested).
This value cannot be null . |
selection |
String : An optional restriction to apply to rows when deleting.
This value may be null . |
selectionArgs |
String : This value may be null . |
Returns | |
---|---|
int |
The number of rows affected. |
Throws | |
---|---|
|
android.database.SQLException |
delete
public int delete (Uri uri, Bundle extras)
Implement this to handle requests to delete one or more rows. The
implementation should apply the selection clause when performing
deletion, allowing the operation to affect multiple rows in a directory.
As a courtesy, call
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.
Parameters | |
---|---|
uri |
Uri : The full URI to query, including a row ID (if a specific
record is requested).
This value cannot be null . |
extras |
Bundle : A Bundle containing additional information necessary for
the operation. Arguments may include SQL style arguments, such
as ContentResolver#QUERY_ARG_SQL_LIMIT , but note that
the documentation for each individual provider will indicate
which arguments they support.
This value may be null . |
Returns | |
---|---|
int |
Throws | |
---|---|
IllegalArgumentException |
if the provider doesn't support one of the requested Bundle arguments. |
|
android.database.SQLException |
dump
public void dump (FileDescriptor fd, PrintWriter writer, String[] args)
Print the Provider's state into the given stream. This gets invoked if you run "adb shell dumpsys activity provider <provider_component_name>".
Parameters | |
---|---|
fd |
FileDescriptor : The raw file descriptor that the dump is being sent to. |
writer |
PrintWriter : The PrintWriter to which you should dump your state. This will be
closed for you after you return. |
args |
String : additional arguments to the dump request. |
getCallingAttributionSource
public final AttributionSource getCallingAttributionSource ()
Gets the attribution source of the calling app. If you want to attribute
the data access to the calling app you can create an attribution context
via Context.createContext(ContextParams)
and passing
this identity to ContextParams.Builder#setNextAttributionSource(
AttributionSource)
.
Returns | |
---|---|
AttributionSource |
The identity of the caller for permission purposes.
This value may be null . |
getCallingAttributionTag
public final String getCallingAttributionTag ()
Return the attribution tag of the caller that initiated the request being
processed on the current thread. Returns null
if not currently processing
a request of the request is for the default attribution.
This will always return null
when processing
getTypeAnonymous(android.net.Uri)
requests
For getType(android.net.Uri)
requests, this will be only available for cases, where
the caller can be identified. See getTypeAnonymous(android.net.Uri)
Returns | |
---|---|
String |
See also:
getCallingPackage
public final String getCallingPackage ()
Return the package name of the caller that initiated the request being
processed on the current thread. The returned package will have been
verified to belong to the calling UID. Returns null
if not
currently processing a request.
This will always return null
when processing
getTypeAnonymous(android.net.Uri)
requests
For getType(android.net.Uri)
requests, this will be only available for cases, where
the caller can be identified. See getTypeAnonymous(android.net.Uri)
Returns | |
---|---|
String |
Throws | |
---|---|
SecurityException |
if the calling package doesn't belong to the calling UID. |
getCallingPackageUnchecked
public final String getCallingPackageUnchecked ()
Return the package name of the caller that initiated the request being
processed on the current thread. The returned package will have
not been verified to belong to the calling UID. Returns
null
if not currently processing a request.
This will always return null
when processing
getTypeAnonymous(android.net.Uri)
requests
For getType(android.net.Uri)
requests, this will be only available for cases, where
the caller can be identified. See getTypeAnonymous(android.net.Uri)
Returns | |
---|---|
String |
getContext
public final Context getContext ()
Retrieves the Context this provider is running in. Only available once
onCreate()
has been called -- this will return null
in the
constructor.
Returns | |
---|---|
Context |
getPathPermissions
public final PathPermission[] getPathPermissions ()
Return the path-based permissions required for read and/or write access to this content provider. This method can be called from multiple threads, as described in Processes and Threads.
Returns | |
---|---|
PathPermission[] |
This value may be null . |
getReadPermission
public final String getReadPermission ()
Return the name of the permission required for read-only access to this content provider. This method can be called from multiple threads, as described in Processes and Threads.
Returns | |
---|---|
String |
This value may be null . |
getStreamTypes
public String[] getStreamTypes (Uri uri, String mimeTypeFilter)
Called by a client to determine the types of data streams that this
content provider supports for the given URI. The default implementation
returns null
, meaning no types. If your content provider stores data
of a particular type, return that MIME type if it matches the given
mimeTypeFilter. If it can perform type conversions, return an array
of all supported MIME types that match mimeTypeFilter.
Parameters | |
---|---|
uri |
Uri : The data in the content provider being queried.
This value cannot be null . |
mimeTypeFilter |
String : The type of data the client desires. May be
a pattern, such as */* to retrieve all possible data types.
This value cannot be null . |
Returns | |
---|---|
String[] |
Returns null if there are no possible data streams for the
given mimeTypeFilter. Otherwise returns an array of all available
concrete MIME types. |
getType
public abstract String getType (Uri uri)
Implement this to handle requests for the MIME type of the data at the
given URI. The returned MIME type should start with
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 by default 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.
If your mime type reveals details that should be protected,
then you should protect this method by implementing getTypeAnonymous(Uri)
.
Implementing getTypeAnonymous(Uri)
ensures your getType(Uri)
can be
only accessed by caller's having associated readPermission for the URI.
Parameters | |
---|---|
uri |
Uri : the URI to query.
This value cannot be null . |
Returns | |
---|---|
String |
a MIME type string, or null if there is no type. |
getTypeAnonymous
public String getTypeAnonymous (Uri uri)
Implement this to handle requests for MIME type of URIs, that does not need to reveal any internal information which should be protected by any permission.
If your mime type reveals details that should be protected, then you should protect those
by implementing those in getType(Uri)
, and in this function, only return types of
URIs which can be obtained by anyone without any access.
Implementing ths function will make sure getType(Uri)
is protected by readPermission.
This function by default works as the getType(Uri)
Parameters | |
---|---|
uri |
Uri : the URI to query.
This value cannot be null . |
Returns | |
---|---|
String |
a MIME type string, or null if type needs to be protected. |
getWritePermission
public final String getWritePermission ()
Return the name of the permission required for read/write access to this content provider. This method can be called from multiple threads, as described in Processes and Threads.
Returns | |
---|---|
String |
This value may be null . |
insert
public Uri insert (Uri uri, ContentValues values, Bundle extras)
Implement this to handle requests to insert a new row. As a courtesy,
call
notifyChange()
after inserting. This method can be called from multiple
threads, as described in Processes
and Threads.
Parameters | |
---|---|
uri |
Uri : The content:// URI of the insertion request.
This value cannot be null . |
values |
ContentValues : A set of column_name/value pairs to add to the database.
This value may be null . |
extras |
Bundle : A Bundle containing additional information necessary for
the operation. Arguments may include SQL style arguments, such
as ContentResolver#QUERY_ARG_SQL_LIMIT , but note that
the documentation for each individual provider will indicate
which arguments they support.
This value may be null . |
Returns | |
---|---|
Uri |
The URI for the newly inserted item.
This value may be null . |
Throws | |
---|---|
IllegalArgumentException |
if the provider doesn't support one of the requested Bundle arguments. |
insert
public abstract Uri insert (Uri uri, ContentValues values)
Implement this to handle requests to insert a new row. As a courtesy,
call
notifyChange()
after inserting. This method can be called from multiple
threads, as described in Processes
and Threads.
Parameters | |
---|---|
uri |
Uri : The content:// URI of the insertion request.
This value cannot be null . |
values |
ContentValues : A set of column_name/value pairs to add to the database.
This value may be null . |
Returns | |
---|---|
Uri |
The URI for the newly inserted item.
This value may be null . |
onCallingPackageChanged
public void onCallingPackageChanged ()
Called whenever the value of getCallingPackage()
changes, giving
the provider an opportunity to invalidate any security related caching it
may be performing.
This typically happens when a ContentProvider
makes a nested call
back into itself when already processing a call from a remote process.
onConfigurationChanged
public void onConfigurationChanged (Configuration newConfig)
Called by the system when the device configuration changes while your component is running. Note that, unlike activities, other components are never restarted when a configuration changes: they must always deal with the results of the change, such as by re-retrieving resources.
At the time that this function has been called, your Resources object will have been updated to return resource values matching the new configuration.
For more information, read Handling Runtime Changes. This method is always called on the application main thread, and must not perform lengthy operations.
The default content provider implementation does nothing. Override this method to take appropriate action. (Content providers do not usually care about things like screen orientation, but may want to know about locale changes.)
Parameters | |
---|---|
newConfig |
Configuration : The new device configuration.
This value cannot be null . |
onCreate
public abstract boolean onCreate ()
Implement this to initialize your content provider on startup. This method is called for all registered content providers on the application main thread at application launch time. It must not perform lengthy operations, or application startup will be delayed.
You should defer nontrivial initialization (such as opening,
upgrading, and scanning databases) until the content provider is used
(via query(Uri, String, Bundle, CancellationSignal)
, insert(Uri, 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(SQLiteDatabase)
to initialize the
database when it is first opened.)
Returns | |
---|---|
boolean |
true if the provider was successfully loaded, false otherwise |
onLowMemory
public void onLowMemory ()
This is called when the overall system is running low on memory, and actively running processes should trim their memory usage. While the exact point at which this will be called is not defined, generally it will happen when all background process have been killed. That is, before reaching the point of killing processes hosting service and foreground UI that we would like to avoid killing. This method is always called on the application main thread, and must not perform lengthy operations.
The default content provider implementation does nothing. Subclasses may override this method to take appropriate action.
onTrimMemory
public void onTrimMemory (int level)
Called when the operating system has determined that it is a good time for a process to trim unneeded memory from its process. You should never compare to exact values of the level, since new intermediate values may be added -- you will typically want to compare if the value is greater or equal to a level you are interested in.
To retrieve the processes current trim level at any point, you can
use ActivityManager.getMyMemoryState(RunningAppProcessInfo)
.
Parameters | |
---|---|
level |
int : The context of the trim, giving a hint of the amount of
trimming the application may like to perform.
Value is ComponentCallbacks2.TRIM_MEMORY_COMPLETE , ComponentCallbacks2.TRIM_MEMORY_MODERATE , ComponentCallbacks2.TRIM_MEMORY_BACKGROUND , ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN , ComponentCallbacks2.TRIM_MEMORY_RUNNING_CRITICAL , ComponentCallbacks2.TRIM_MEMORY_RUNNING_LOW , or ComponentCallbacks2.TRIM_MEMORY_RUNNING_MODERATE |
openAssetFile
public AssetFileDescriptor openAssetFile (Uri uri, String mode, CancellationSignal signal)
This is like openFile(Uri, 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
, 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 getType(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
.
Parameters | |
---|---|
uri |
Uri : The URI whose file is to be opened.
This value cannot be null . |
mode |
String : The string representation of the file mode. Can be "r", "w", "wt", "wa", "rw"
or "rwt". Please note the exact implementation of these may differ for each
Provider implementation - for example, "w" may or may not truncate.
This value cannot be null . |
signal |
CancellationSignal : A signal to cancel the operation in progress, or
null if none. For example, if you are downloading a
file from the network to service a "rw" mode request, you
should periodically call
CancellationSignal#throwIfCanceled() to check whether
the client has canceled the request and abort the download. |
Returns | |
---|---|
AssetFileDescriptor |
Returns a new AssetFileDescriptor which you can use to access
the file.
This value may be null . |
Throws | |
---|---|
FileNotFoundException |
Throws FileNotFoundException if there is no file associated with the given URI or the mode is invalid. |
SecurityException |
Throws SecurityException if the caller does not have permission to access the file. |
openAssetFile
public AssetFileDescriptor openAssetFile (Uri uri, String mode)
This is like openFile(Uri, 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
, 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 getType(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
.
Parameters | |
---|---|
uri |
Uri : The URI whose file is to be opened.
This value cannot be null . |
mode |
String : The string representation of the file mode. Can be "r", "w", "wt", "wa", "rw"
or "rwt". Please note the exact implementation of these may differ for each
Provider implementation - for example, "w" may or may not truncate.
This value cannot be null . |
Returns | |
---|---|
AssetFileDescriptor |
Returns a new AssetFileDescriptor which you can use to access
the file.
This value may be null . |
Throws | |
---|---|
FileNotFoundException |
Throws FileNotFoundException if there is no file associated with the given URI or the mode is invalid. |
SecurityException |
Throws SecurityException if the caller does not have permission to access the file. |
openFile
public ParcelFileDescriptor openFile (Uri uri, String mode, CancellationSignal signal)
Override this to handle requests to open a file blob.
The default implementation always throws FileNotFoundException
.
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.
If opened with the exclusive "r" or "w" modes, the returned ParcelFileDescriptor can be a pipe or socket pair to enable streaming of data. Opening with the "rw" or "rwt" modes implies a file on disk that supports seeking.
If you need to detect when the returned ParcelFileDescriptor has been
closed, or if the remote process has crashed or encountered some other
error, you can use ParcelFileDescriptor#open(File, int,
android.os.Handler, android.os.ParcelFileDescriptor.OnCloseListener)
,
ParcelFileDescriptor#createReliablePipe()
, or
ParcelFileDescriptor#createReliableSocketPair()
.
For use in Intents, you will want to implement getType(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
.
You may also want to support other common columns if you have additional meta-data
to supply, such as MediaStore.MediaColumns.DATE_ADDED
in MediaStore.MediaColumns
.
Parameters | |
---|---|
uri |
Uri : The URI whose file is to be opened.
This value cannot be null . |
mode |
String : The string representation of the file mode. Can be "r", "w", "wt", "wa", "rw"
or "rwt". Please note the exact implementation of these may differ for each
Provider implementation - for example, "w" may or may not truncate.
This value cannot be null . |
signal |
CancellationSignal : A signal to cancel the operation in progress, or
null if none. For example, if you are downloading a
file from the network to service a "rw" mode request, you
should periodically call
CancellationSignal#throwIfCanceled() to check whether
the client has canceled the request and abort the download. |
Returns | |
---|---|
ParcelFileDescriptor |
Returns a new ParcelFileDescriptor which you can use to access
the file.
This value may be null . |
Throws | |
---|---|
FileNotFoundException |
Throws FileNotFoundException if there is no file associated with the given URI or the mode is invalid. |
SecurityException |
Throws SecurityException if the caller does not have permission to access the file. |
openFile
public ParcelFileDescriptor openFile (Uri uri, String mode)
Override this to handle requests to open a file blob.
The default implementation always throws FileNotFoundException
.
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.
If opened with the exclusive "r" or "w" modes, the returned ParcelFileDescriptor can be a pipe or socket pair to enable streaming of data. Opening with the "rw" or "rwt" modes implies a file on disk that supports seeking.
If you need to detect when the returned ParcelFileDescriptor has been
closed, or if the remote process has crashed or encountered some other
error, you can use ParcelFileDescriptor#open(File, int,
android.os.Handler, android.os.ParcelFileDescriptor.OnCloseListener)
,
ParcelFileDescriptor#createReliablePipe()
, or
ParcelFileDescriptor#createReliableSocketPair()
.
If you need to return a large file that isn't backed by a real file on
disk, such as a file on a network share or cloud storage service,
consider using
StorageManager#openProxyFileDescriptor(int, android.os.ProxyFileDescriptorCallback, android.os.Handler)
which will let you to stream the content on-demand.
For use in Intents, you will want to implement getType(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
.
You may also want to support other common columns if you have additional meta-data
to supply, such as MediaStore.MediaColumns.DATE_ADDED
in MediaStore.MediaColumns
.
Parameters | |
---|---|
uri |
Uri : The URI whose file is to be opened.
This value cannot be null . |
mode |
String : The string representation of the file mode. Can be "r", "w", "wt", "wa", "rw"
or "rwt". Please note the exact implementation of these may differ for each
Provider implementation - for example, "w" may or may not truncate.
This value cannot be null . |
Returns | |
---|---|
ParcelFileDescriptor |
Returns a new ParcelFileDescriptor which you can use to access
the file.
This value may be null . |
Throws | |
---|---|
FileNotFoundException |
Throws FileNotFoundException if there is no file associated with the given URI or the mode is invalid. |
SecurityException |
Throws SecurityException if the caller does not have permission to access the file. |
openPipeHelper
public ParcelFileDescriptor openPipeHelper (Uri uri, String mimeType, Bundle opts, T args, PipeDataWriter<T> func)
A helper function for implementing openTypedAssetFile(Uri, String, Bundle)
, for
creating a data pipe and background thread allowing you to stream
generated data back to the client. This function returns a new
ParcelFileDescriptor that should be returned to the caller (the caller
is responsible for closing it).
Parameters | |
---|---|
uri |
Uri : The URI whose data is to be written.
This value cannot be null . |
mimeType |
String : The desired type of data to be written.
This value cannot be null . |
opts |
Bundle : Options supplied by caller.
This value may be null . |
args |
T : Your own custom arguments.
This value may be null . |
func |
PipeDataWriter : Interface implementing the function that will actually
stream the data.
This value cannot be null . |
Returns | |
---|---|
ParcelFileDescriptor |
Returns a new ParcelFileDescriptor holding the read side of
the pipe. This should be returned to the caller for reading; the caller
is responsible for closing it when done.
This value cannot be null . |
Throws | |
---|---|
FileNotFoundException |
openTypedAssetFile
public AssetFileDescriptor openTypedAssetFile (Uri uri, String mimeTypeFilter, Bundle opts, CancellationSignal signal)
Called by a client to open a read-only stream containing data of a
particular MIME type. This is like openAssetFile(android.net.Uri, java.lang.String)
,
except the file can only be read-only and the content provider may
perform data conversions to generate data of the desired type.
The default implementation compares the given mimeType against the
result of getType(android.net.Uri)
and, if they match, simply calls
openAssetFile(android.net.Uri, java.lang.String)
.
See ClipData
for examples of the use and implementation
of this method.
The returned AssetFileDescriptor can be a pipe or socket pair to enable streaming of data.
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
.
You may also want to support other common columns if you have additional meta-data
to supply, such as MediaStore.MediaColumns.DATE_ADDED
in MediaStore.MediaColumns
.
Parameters | |
---|---|
uri |
Uri : The data in the content provider being queried.
This value cannot be null . |
mimeTypeFilter |
String : The type of data the client desires. May be
a pattern, such as */*, if the caller does not have specific type
requirements; in this case the content provider will pick its best
type matching the pattern.
This value cannot be null . |
opts |
Bundle : Additional options from the client. The definitions of
these are specific to the content provider being called.
This value may be null . |
signal |
CancellationSignal : A signal to cancel the operation in progress, or
null if none. For example, if you are downloading a
file from the network to service a "rw" mode request, you
should periodically call
CancellationSignal#throwIfCanceled() to check whether
the client has canceled the request and abort the download. |
Returns | |
---|---|
AssetFileDescriptor |
Returns a new AssetFileDescriptor from which the client can
read data of the desired type.
This value may be null . |
Throws | |
---|---|
FileNotFoundException |
Throws FileNotFoundException if there is no file associated with the given URI or the mode is invalid. |
SecurityException |
Throws SecurityException if the caller does not have permission to access the data. |
IllegalArgumentException |
Throws IllegalArgumentException if the content provider does not support the requested MIME type. |
openTypedAssetFile
public AssetFileDescriptor openTypedAssetFile (Uri uri, String mimeTypeFilter, Bundle opts)
Called by a client to open a read-only stream containing data of a
particular MIME type. This is like openAssetFile(android.net.Uri, java.lang.String)
,
except the file can only be read-only and the content provider may
perform data conversions to generate data of the desired type.
The default implementation compares the given mimeType against the
result of getType(android.net.Uri)
and, if they match, simply calls
openAssetFile(android.net.Uri, java.lang.String)
.
See ClipData
for examples of the use and implementation
of this method.
The returned AssetFileDescriptor can be a pipe or socket pair to enable streaming of data.
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
.
You may also want to support other common columns if you have additional meta-data
to supply, such as MediaStore.MediaColumns.DATE_ADDED
in MediaStore.MediaColumns
.
Parameters | |
---|---|
uri |
Uri : The data in the content provider being queried.
This value cannot be null . |
mimeTypeFilter |
String : The type of data the client desires. May be
a pattern, such as */*, if the caller does not have specific type
requirements; in this case the content provider will pick its best
type matching the pattern.
This value cannot be null . |
opts |
Bundle : Additional options from the client. The definitions of
these are specific to the content provider being called.
This value may be null . |
Returns | |
---|---|
AssetFileDescriptor |
Returns a new AssetFileDescriptor from which the client can
read data of the desired type.
This value may be null . |
Throws | |
---|---|
FileNotFoundException |
Throws FileNotFoundException if there is no file associated with the given URI or the mode is invalid. |
SecurityException |
Throws SecurityException if the caller does not have permission to access the data. |
IllegalArgumentException |
Throws IllegalArgumentException if the content provider does not support the requested MIME type. |
query
public Cursor query (Uri uri, String[] projection, Bundle queryArgs, CancellationSignal cancellationSignal)
Implement this to handle query requests where the arguments are packed into a Bundle
.
Arguments may include traditional SQL style query arguments. When present these
should be handled according to the contract established in
query(android.net.Uri, java.lang.String[], java.lang.String, java.lang.String[], java.lang.String, android.os.CancellationSignal)
.
Traditional SQL arguments can be found in the bundle using the following keys:
ContentResolver.QUERY_ARG_SQL_SELECTION
ContentResolver.QUERY_ARG_SQL_SELECTION_ARGS
ContentResolver.QUERY_ARG_SQL_SORT_ORDER
This method can be called from multiple threads, as described in Processes and Threads.
Example client call:
// Request 20 records starting at row index 30. Bundle queryArgs = new Bundle(); queryArgs.putInt(ContentResolver.QUERY_ARG_OFFSET, 30); queryArgs.putInt(ContentResolver.QUERY_ARG_LIMIT, 20); Cursor cursor = getContentResolver().query( contentUri, // Content Uri is specific to individual content providers. projection, // String[] describing which columns to return. queryArgs, // Query arguments. null); // Cancellation signal.
int recordsetSize = 0x1000; // Actual value is implementation specific. queryArgs = queryArgs != null ? queryArgs : Bundle.EMPTY; // ensure queryArgs is non-null int offset = queryArgs.getInt(ContentResolver.QUERY_ARG_OFFSET, 0); int limit = queryArgs.getInt(ContentResolver.QUERY_ARG_LIMIT, Integer.MIN_VALUE); MatrixCursor c = new MatrixCursor(PROJECTION, limit); // Calculate the number of items to include in the cursor. int numItems = MathUtils.constrain(recordsetSize - offset, 0, limit); // Build the paged result set.... for (int i = offset; i < offset + numItems; i++) { // populate row from your data. } Bundle extras = new Bundle(); c.setExtras(extras); // Any QUERY_ARG_* key may be included if honored. // In an actual implementation, include only keys that are both present in queryArgs // and reflected in the Cursor output. For example, if QUERY_ARG_OFFSET were included // in queryArgs, but was ignored because it contained an invalid value (like \u2013273), // then QUERY_ARG_OFFSET should be omitted. extras.putStringArray(ContentResolver.EXTRA_HONORED_ARGS, new String[] { ContentResolver.QUERY_ARG_OFFSET, ContentResolver.QUERY_ARG_LIMIT }); extras.putInt(ContentResolver.EXTRA_TOTAL_COUNT, recordsetSize); cursor.setNotificationUri(getContext().getContentResolver(), uri); return cursor;
See query(android.net.Uri, java.lang.String[], java.lang.String, java.lang.String[], java.lang.String, android.os.CancellationSignal)
for implementation details.
Parameters | |
---|---|
uri |
Uri : The URI to query. This will be the full URI sent by the client.
This value cannot be null . |
projection |
String : The list of columns to put into the cursor.
If null provide a default set of columns. |
queryArgs |
Bundle : A Bundle containing additional information necessary for
the operation. Arguments may include SQL style arguments, such
as ContentResolver#QUERY_ARG_SQL_LIMIT , but note that
the documentation for each individual provider will indicate
which arguments they support.
This value may be null . |
cancellationSignal |
CancellationSignal : A signal to cancel the operation in progress,
or null . |
Returns | |
---|---|
Cursor |
a Cursor or null . |
query
public Cursor query (Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder, CancellationSignal cancellationSignal)
Implement this to handle query requests from clients with support for cancellation.
Apps targeting Build.VERSION_CODES.O
or higher should override
query(android.net.Uri, java.lang.String[], android.os.Bundle, android.os.CancellationSignal)
instead of this method.
This method can be called from multiple threads, as described in Processes and Threads.
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.
// SQLiteQueryBuilder is a helper class that creates the // proper SQL syntax for us. SQLiteQueryBuilder qBuilder = new SQLiteQueryBuilder(); // Guard against SQL injection attacks qBuilder.setStrict(true); qBuilder.setProjectionMap(MAP_OF_QUERYABLE_COLUMNS); qBuilder.setStrictColumns(true); qBuilder.setStrictGrammar(true); // 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;
If you implement this method then you must also implement the version of
query(android.net.Uri, java.lang.String[], java.lang.String, java.lang.String[], java.lang.String)
that does not take a cancellation
signal to ensure correct operation on older versions of the Android Framework in
which the cancellation signal overload was not available.
Parameters | |
---|---|
uri |
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.
This value cannot be null . |
projection |
String : The list of columns to put into the cursor. If
null all columns are included. |
selection |
String : A selection criteria to apply when filtering rows.
If null then all rows are included. |
selectionArgs |
String : 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.
This value may be null . |
sortOrder |
String : How the rows in the cursor should be sorted.
If null then the provider is free to define the sort order. |
cancellationSignal |
CancellationSignal : A signal to cancel the operation in progress, or null if none.
If the operation is canceled, then OperationCanceledException will be thrown
when the query is executed. |
Returns | |
---|---|
Cursor |
a Cursor or null . |
query
public abstract Cursor query (Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder)
Implement this to handle query requests from clients.
Apps targeting Build.VERSION_CODES.O
or higher should override
query(android.net.Uri, java.lang.String[], android.os.Bundle, android.os.CancellationSignal)
and provide a stub
implementation of this method.
This method can be called from multiple threads, as described in Processes and Threads.
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.
// SQLiteQueryBuilder is a helper class that creates the // proper SQL syntax for us. SQLiteQueryBuilder qBuilder = new SQLiteQueryBuilder(); // Guard against SQL injection attacks qBuilder.setStrict(true); qBuilder.setProjectionMap(MAP_OF_QUERYABLE_COLUMNS); qBuilder.setStrictColumns(true); qBuilder.setStrictGrammar(true); // 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;
Parameters | |
---|---|
uri |
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.
This value cannot be null . |
projection |
String : The list of columns to put into the cursor. If
null all columns are included. |
selection |
String : A selection criteria to apply when filtering rows.
If null then all rows are included. |
selectionArgs |
String : 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.
This value may be null . |
sortOrder |
String : How the rows in the cursor should be sorted.
If null then the provider is free to define the sort order. |
Returns | |
---|---|
Cursor |
a Cursor or null . |
refresh
public boolean refresh (Uri uri, Bundle extras, CancellationSignal cancellationSignal)
Implement this to support refresh of content identified by uri
.
By default, this method returns false; providers who wish to implement
this should return true to signal the client that the provider has tried
refreshing with its own implementation.
This allows clients to request an explicit refresh of content identified
by uri
.
Client code should only invoke this method when there is a strong indication (such as a user initiated pull to refresh gesture) that the content is stale.
Remember to send
ContentResolver#notifyChange(Uri, android.database.ContentObserver)
notifications when content changes.
Parameters | |
---|---|
uri |
Uri : The Uri identifying the data to refresh. |
extras |
Bundle : Additional options from the client. The definitions of
these are specific to the content provider being called.
This value may be null . |
cancellationSignal |
CancellationSignal : A signal to cancel the operation in progress,
or null if none. For example, if you called refresh on
a particular uri, you should call
CancellationSignal#throwIfCanceled() to check whether
the client has canceled the refresh request. |
Returns | |
---|---|
boolean |
true if the provider actually tried refreshing. |
requireContext
public final Context requireContext ()
Retrieves a Non-Nullable Context this provider is running in, this is intended to be called
after onCreate()
. When called before context was created, an IllegalStateException
will be thrown.
Note A provider must be declared in the manifest and created automatically by the system,
and context is only available after onCreate()
is called.
Returns | |
---|---|
Context |
This value cannot be null . |
restoreCallingIdentity
public final void restoreCallingIdentity (ContentProvider.CallingIdentity identity)
Restore the identity of the incoming IPC on the current thread back to a
previously identity that was returned by clearCallingIdentity()
.
Internally this calls Binder#restoreCallingIdentity(long)
and
also restores any value stored in getCallingPackage()
.
Parameters | |
---|---|
identity |
ContentProvider.CallingIdentity : This value cannot be null . |
shutdown
public void shutdown ()
Implement this to shut down the ContentProvider instance. You can then invoke this method in unit tests.
Android normally handles ContentProvider startup and shutdown automatically. You do not need to start up or shut down a ContentProvider. When you invoke a test method on a ContentProvider, however, a ContentProvider instance is started and keeps running after the test finishes, even if a succeeding test instantiates another ContentProvider. A conflict develops because the two instances are usually running against the same underlying data source (for example, an sqlite database).
Implementing shutDown() avoids this conflict by providing a way to terminate the ContentProvider. This method can also prevent memory leaks from multiple instantiations of the ContentProvider, and it can ensure unit test isolation by allowing you to completely clean up the test fixture before moving on to the next test.
uncanonicalize
public Uri uncanonicalize (Uri url)
Remove canonicalization from canonical URIs previously returned by
canonicalize(Uri)
. For example, if your implementation is to add
a query param to canonicalize a URI, this method can simply trip any
query params on the URI. The default implementation always returns the
same url that was passed in.
Parameters | |
---|---|
url |
Uri : The Uri to remove any canonicalization from.
This value cannot be null . |
Returns | |
---|---|
Uri |
Return the non-canonical representation of url, return the url as-is if there is nothing to do, or return null if the data identified by the canonical representation can not be found in the current environment. |
update
public int update (Uri uri, ContentValues values, Bundle extras)
Implement this to handle requests to update one or more rows. The
implementation should update all rows matching the selection to set the
columns according to the provided values map. As a courtesy, call
notifyChange()
after updating. This method can be called from multiple
threads, as described in Processes
and Threads.
Parameters | |
---|---|
uri |
Uri : The URI to query. This can potentially have a record ID if
this is an update request for a specific record.
This value cannot be null . |
values |
ContentValues : A set of column_name/value pairs to update in the database.
This value may be null . |
extras |
Bundle : A Bundle containing additional information necessary for
the operation. Arguments may include SQL style arguments, such
as ContentResolver#QUERY_ARG_SQL_LIMIT , but note that
the documentation for each individual provider will indicate
which arguments they support.
This value may be null . |
Returns | |
---|---|
int |
the number of rows affected. |
Throws | |
---|---|
IllegalArgumentException |
if the provider doesn't support one of the requested Bundle arguments. |
update
public abstract int update (Uri uri, ContentValues values, String selection, String[] selectionArgs)
Implement this to handle requests to update one or more rows. The
implementation should update all rows matching the selection to set the
columns according to the provided values map. As a courtesy, call
notifyChange()
after updating. This method can be called from multiple
threads, as described in Processes
and Threads.
Parameters | |
---|---|
uri |
Uri : The URI to query. This can potentially have a record ID if
this is an update request for a specific record.
This value cannot be null . |
values |
ContentValues : A set of column_name/value pairs to update in the database.
This value may be null . |
selection |
String : An optional filter to match rows to update.
This value may be null . |
selectionArgs |
String : This value may be null . |
Returns | |
---|---|
int |
the number of rows affected. |
Protected methods
isTemporary
protected boolean isTemporary ()
Returns true if this instance is a temporary content provider.
Returns | |
---|---|
boolean |
true if this instance is a temporary content provider |
openFileHelper
protected final ParcelFileDescriptor openFileHelper (Uri uri, String mode)
Convenience for subclasses that wish to implement openFile(Uri, String)
by looking up a column named "_data" at the given URI.
Parameters | |
---|---|
uri |
Uri : The URI to be opened.
This value cannot be null . |
mode |
String : The string representation of the file mode. Can be "r", "w", "wt", "wa", "rw"
or "rwt". Please note the exact implementation of these may differ for each
Provider implementation - for example, "w" may or may not truncate.
This value cannot be null . |
Returns | |
---|---|
ParcelFileDescriptor |
Returns a new ParcelFileDescriptor that can be used by the
client to access the file.
This value cannot be null . |
Throws | |
---|---|
FileNotFoundException |
setPathPermissions
protected final void setPathPermissions (PathPermission[] permissions)
Change the path-based permission required to read and/or write data in the content provider. This is normally set for you from its manifest information when the provider is first created.
Parameters | |
---|---|
permissions |
PathPermission : Array of path permission descriptions.
This value may be null . |
setReadPermission
protected final void setReadPermission (String permission)
Change the permission required to read data from the content provider. This is normally set for you from its manifest information when the provider is first created.
Parameters | |
---|---|
permission |
String : Name of the permission required for read-only access.
This value may be null . |
setWritePermission
protected final void setWritePermission (String permission)
Change the permission required to read and write data in the content provider. This is normally set for you from its manifest information when the provider is first created.
Parameters | |
---|---|
permission |
String : Name of the permission required for read/write access.
This value may be null . |
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Last updated 2024-06-18 UTC.