/*
* Copyright (C) 2006 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.content;
import android.content.pm.PackageManager;
import android.content.pm.ProviderInfo;
import android.content.res.AssetFileDescriptor;
import android.content.res.Configuration;
import android.database.Cursor;
import android.database.CursorToBulkCursorAdaptor;
import android.database.CursorWindow;
import android.database.IBulkCursor;
import android.database.IContentObserver;
import android.database.SQLException;
import android.net.Uri;
import android.os.Binder;
import android.os.ParcelFileDescriptor;
import java.io.File;
import java.io.FileNotFoundException;
/**
* 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
* {@link 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
* {@link android.database.sqlite.SQLiteDatabase}.
*
* <p>For more information, read <a href="{@docRoot}guide/topics/providers/content-providers.html">Content
* Providers</a>.</p>
*
* <p>When a request is made via
* a {@link 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 {@link UriMatcher} class is helpful for parsing
* URIs.</p>
*
* <p>The primary methods that need to be implemented are:
* <ul>
* <li>{@link #query} which returns data to the caller</li>
* <li>{@link #insert} which inserts new data into the content provider</li>
* <li>{@link #update} which updates existing data in the content provider</li>
* <li>{@link #delete} which deletes data from the content provider</li>
* <li>{@link #getType} which returns the MIME type of data in the content provider</li>
* </ul></p>
*
* <p>This class takes care of cross process calls so subclasses don't have to worry about which
* process a request is coming from.</p>
*/
public abstract class ContentProvider implements ComponentCallbacks {
private Context mContext = null;
private String mReadPermission;
private String mWritePermission;
private Transport mTransport = new Transport();
/**
* Given an IContentProvider, try to coerce it back to the real
* ContentProvider object if it is running in the local process. This can
* be used if you know you are running in the same process as a provider,
* and want to get direct access to its implementation details. Most
* clients should not nor have a reason to use it.
*
* @param abstractInterface The ContentProvider interface that is to be
* coerced.
* @return If the IContentProvider is non-null and local, returns its actual
* ContentProvider instance. Otherwise returns null.
* @hide
*/
public static ContentProvider coerceToLocalContentProvider(
IContentProvider abstractInterface) {
if (abstractInterface instanceof Transport) {
return ((Transport)abstractInterface).getContentProvider();
}
return null;
}
/**
* Binder object that deals with remoting.
*
* @hide
*/
class Transport extends ContentProviderNative {
ContentProvider getContentProvider() {
return ContentProvider.this;
}
/**
* Remote version of a query, which returns an IBulkCursor. The bulk
* cursor should be wrapped with BulkCursorToCursorAdaptor before use.
*/
public IBulkCursor bulkQuery(Uri uri, String[] projection,
String selection, String[] selectionArgs, String sortOrder,
IContentObserver observer, CursorWindow window) {
checkReadPermission(uri);
Cursor cursor = ContentProvider.this.query(uri, projection,
selection, selectionArgs, sortOrder);
if (cursor == null) {
return null;
}
String wperm = getWritePermission();
return new CursorToBulkCursorAdaptor(cursor, observer,
ContentProvider.this.getClass().getName(),
wperm == null ||
getContext().checkCallingOrSelfPermission(getWritePermission())
== PackageManager.PERMISSION_GRANTED,
window);
}
public Cursor query(Uri uri, String[] projection,
String selection, String[] selectionArgs, String sortOrder) {
checkReadPermission(uri);
return ContentProvider.this.query(uri, projection, selection,
selectionArgs, sortOrder);
}
public String getType(Uri uri) {
return ContentProvider.this.getType(uri);
}
public Uri insert(Uri uri, ContentValues initialValues) {
checkWritePermission(uri);
return ContentProvider.this.insert(uri, initialValues);
}
public int bulkInsert(Uri uri, ContentValues[] initialValues) {
checkWritePermission(uri);
return ContentProvider.this.bulkInsert(uri, initialValues);
}
public int delete(Uri uri, String selection, String[] selectionArgs) {
checkWritePermission(uri);
return ContentProvider.this.delete(uri, selection, selectionArgs);
}
public int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs) {
checkWritePermission(uri);
return ContentProvider.this.update(uri, values, selection, selectionArgs);
}
public ParcelFileDescriptor openFile(Uri uri, String mode)
throws FileNotFoundException {
if (mode != null && mode.startsWith("rw")) checkWritePermission(uri);
else checkReadPermission(uri);
return ContentProvider.this.openFile(uri, mode);
}
public AssetFileDescriptor openAssetFile(Uri uri, String mode)
throws FileNotFoundException {
if (mode != null && mode.startsWith("rw")) checkWritePermission(uri);
else checkReadPermission(uri);
return ContentProvider.this.openAssetFile(uri, mode);
}
public ISyncAdapter getSyncAdapter() {
checkWritePermission(null);
SyncAdapter sa = ContentProvider.this.getSyncAdapter();
return sa != null ? sa.getISyncAdapter() : null;
}
private void checkReadPermission(Uri uri) {
final String rperm = getReadPermission();
final int pid = Binder.getCallingPid();
final int uid = Binder.getCallingUid();
if (getContext().checkUriPermission(uri, rperm, null, pid, uid,
Intent.FLAG_GRANT_READ_URI_PERMISSION)
== PackageManager.PERMISSION_GRANTED) {
return;
}
String msg = "Permission Denial: reading "
+ ContentProvider.this.getClass().getName()
+ " uri " + uri + " from pid=" + Binder.getCallingPid()
+ ", uid=" + Binder.getCallingUid()
+ " requires " + rperm;
throw new SecurityException(msg);
}
private void checkWritePermission(Uri uri) {
final String wperm = getWritePermission();
final int pid = Binder.getCallingPid();
final int uid = Binder.getCallingUid();
if (getContext().checkUriPermission(uri, null, wperm, pid, uid,
Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
== PackageManager.PERMISSION_GRANTED) {
return;
}
String msg = "Permission Denial: writing "
+ ContentProvider.this.getClass().getName()
+ " uri " + uri + " from pid=" + Binder.getCallingPid()
+ ", uid=" + Binder.getCallingUid()
+ " requires " + wperm;
throw new SecurityException(msg);
}
}
/**
* Retrieve the Context this provider is running in. Only available once
* onCreate(Map icicle) has been called -- this will be null in the
* constructor.
*/
public final Context getContext() {
return mContext;
}
/**
* 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.
*
* @param permission Name of the permission required for read-only access.
*/
protected final void setReadPermission(String permission) {
mReadPermission = permission;
}
/**
* 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
* <a href="{@docRoot}guide/topics/fundamentals.html#procthread">Application Fundamentals:
* Processes and Threads</a>.
*/
public final String getReadPermission() {
return mReadPermission;
}
/**
* 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.
*
* @param permission Name of the permission required for read/write access.
*/
protected final void setWritePermission(String permission) {
mWritePermission = permission;
}
/**
* 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
* <a href="{@docRoot}guide/topics/fundamentals.html#procthread">Application Fundamentals:
* Processes and Threads</a>.
*/
public final String getWritePermission() {
return mWritePermission;
}
/**
* Called when the provider is being started.
*
* @return true if the provider was successfully loaded, false otherwise
*/
public abstract boolean onCreate();
public void onConfigurationChanged(Configuration newConfig) {
}
public void onLowMemory() {
}
/**
* Receives a query request from a client in a local process, and
* returns a Cursor. This is called internally by the {@link ContentResolver}.
* This method can be called from multiple
* threads, as described in
* <a href="{@docRoot}guide/topics/fundamentals.html#procthread">Application Fundamentals:
* Processes and Threads</a>.
* <p>
* Example client call:<p>
* <pre>// Request a specific record.
* Cursor managedCursor = managedQuery(
Contacts.People.CONTENT_URI.addId(2),
projection, // Which columns to return.
null, // WHERE clause.
People.NAME + " ASC"); // Sort order.</pre>
* Example implementation:<p>
* <pre>// 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;</pre>
*
* @param 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.
* @param projection The list of columns to put into the cursor. If
* null all columns are included.
* @param selection A selection criteria to apply when filtering rows.
* If null then all rows are included.
* @param sortOrder How the rows in the cursor should be sorted.
* If null then the provider is free to define the sort order.
* @return a Cursor or null.
*/
public abstract Cursor query(Uri uri, String[] projection,
String selection, String[] selectionArgs, String sortOrder);
/**
* Return the MIME type of the data at the given URI. This should start with
* <code>vnd.android.cursor.item</code> for a single record,
* or <code>vnd.android.cursor.dir/</code> for multiple items.
* This method can be called from multiple
* threads, as described in
* <a href="{@docRoot}guide/topics/fundamentals.html#procthread">Application Fundamentals:
* Processes and Threads</a>.
*
* @param uri the URI to query.
* @return a MIME type string, or null if there is no type.
*/
public abstract String getType(Uri uri);
/**
* Implement this to insert a new row.
* As a courtesy, call {@link ContentResolver#notifyChange(android.net.Uri ,android.database.ContentObserver) notifyChange()}
* after inserting.
* This method can be called from multiple
* threads, as described in
* <a href="{@docRoot}guide/topics/fundamentals.html#procthread">Application Fundamentals:
* Processes and Threads</a>.
* @param uri The content:// URI of the insertion request.
* @param values A set of column_name/value pairs to add to the database.
* @return The URI for the newly inserted item.
*/
public abstract Uri insert(Uri uri, ContentValues values);
/**
* Implement this to insert a set of new rows, or the default implementation will
* iterate over the values and call {@link #insert} on each of them.
* As a courtesy, call {@link ContentResolver#notifyChange(android.net.Uri ,android.database.ContentObserver) notifyChange()}
* after inserting.
* This method can be called from multiple
* threads, as described in
* <a href="{@docRoot}guide/topics/fundamentals.html#procthread">Application Fundamentals:
* Processes and Threads</a>.
*
* @param uri The content:// URI of the insertion request.
* @param values An array of sets of column_name/value pairs to add to the database.
* @return The number of values that were inserted.
*/
public int bulkInsert(Uri uri, ContentValues[] values) {
int numValues = values.length;
for (int i = 0; i < numValues; i++) {
insert(uri, values[i]);
}
return numValues;
}
/**
* A request to delete one or more rows. The selection clause is applied when performing
* the deletion, allowing the operation to affect multiple rows in a
* directory.
* As a courtesy, call {@link ContentResolver#notifyChange(android.net.Uri ,android.database.ContentObserver) notifyDelete()}
* after deleting.
* This method can be called from multiple
* threads, as described in
* <a href="{@docRoot}guide/topics/fundamentals.html#procthread">Application Fundamentals:
* Processes and Threads</a>.
*
* <p>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 <code>content://contacts/people/22</code> and the implementation is
* responsible for parsing the record number (22) when creating a SQL statement.
*
* @param uri The full URI to query, including a row ID (if a specific record is requested).
* @param selection An optional restriction to apply to rows when deleting.
* @return The number of rows affected.
* @throws SQLException
*/
public abstract int delete(Uri uri, String selection, String[] selectionArgs);
/**
* Update a content URI. All rows matching the optionally provided selection
* will have their columns listed as the keys in the values map with the
* values of those keys.
* As a courtesy, call {@link ContentResolver#notifyChange(android.net.Uri ,android.database.ContentObserver) notifyChange()}
* after updating.
* This method can be called from multiple
* threads, as described in
* <a href="{@docRoot}guide/topics/fundamentals.html#procthread">Application Fundamentals:
* Processes and Threads</a>.
*
* @param uri The URI to query. This can potentially have a record ID if this
* is an update request for a specific record.
* @param values A Bundle mapping from column names to new column values (NULL is a
* valid value).
* @param selection An optional filter to match rows to update.
* @return the number of rows affected.
*/
public abstract int update(Uri uri, ContentValues values, String selection,
String[] selectionArgs);
/**
* Open a file blob associated with a content URI.
* This method can be called from multiple
* threads, as described in
* <a href="{@docRoot}guide/topics/fundamentals.html#procthread">Application Fundamentals:
* Processes and Threads</a>.
*
* <p>Returns a
* ParcelFileDescriptor, from which you can obtain a
* {@link java.io.FileDescriptor} for use with
* {@link java.io.FileInputStream}, {@link java.io.FileOutputStream}, etc.
* This can be used to store large data (such as an image) associated with
* a particular piece of content.
*
* <p>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.
*
* @param uri The URI whose file is to be opened.
* @param 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.
*
* @return Returns a new ParcelFileDescriptor which you can use to access
* the file.
*
* @throws FileNotFoundException Throws FileNotFoundException if there is
* no file associated with the given URI or the mode is invalid.
* @throws SecurityException Throws SecurityException if the caller does
* not have permission to access the file.
*
* @see #openAssetFile(Uri, String)
* @see #openFileHelper(Uri, String)
*/
public ParcelFileDescriptor openFile(Uri uri, String mode)
throws FileNotFoundException {
throw new FileNotFoundException("No files supported by provider at "
+ uri);
}
/**
* This is like {@link #openFile}, but can be implemented by providers
* that need to be able to return sub-sections of files, often assets
* inside of their .apk. Note that when implementing this your clients
* must be able to deal with such files, either directly with
* {@link ContentResolver#openAssetFileDescriptor
* ContentResolver.openAssetFileDescriptor}, or by using the higher-level
* {@link ContentResolver#openInputStream ContentResolver.openInputStream}
* or {@link ContentResolver#openOutputStream ContentResolver.openOutputStream}
* methods.
*
* <p><em>Note: if you are implementing this to return a full file, you
* should create the AssetFileDescriptor with
* {@link AssetFileDescriptor#UNKNOWN_LENGTH} to be compatible with
* applications that can not handle sub-sections of files.</em></p>
*
* @param uri The URI whose file is to be opened.
* @param 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.
*
* @return Returns a new AssetFileDescriptor which you can use to access
* the file.
*
* @throws FileNotFoundException Throws FileNotFoundException if there is
* no file associated with the given URI or the mode is invalid.
* @throws SecurityException Throws SecurityException if the caller does
* not have permission to access the file.
*
* @see #openFile(Uri, String)
* @see #openFileHelper(Uri, String)
*/
public AssetFileDescriptor openAssetFile(Uri uri, String mode)
throws FileNotFoundException {
ParcelFileDescriptor fd = openFile(uri, mode);
return fd != null ? new AssetFileDescriptor(fd, 0, -1) : null;
}
/**
* Convenience for subclasses that wish to implement {@link #openFile}
* by looking up a column named "_data" at the given URI.
*
* @param uri The URI to be opened.
* @param mode The file mode. 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.
*
* @return Returns a new ParcelFileDescriptor that can be used by the
* client to access the file.
*/
protected final ParcelFileDescriptor openFileHelper(Uri uri,
String mode) throws FileNotFoundException {
Cursor c = query(uri, new String[]{"_data"}, null, null, null);
int count = (c != null) ? c.getCount() : 0;
if (count != 1) {
// If there is not exactly one result, throw an appropriate
// exception.
if (c != null) {
c.close();
}
if (count == 0) {
throw new FileNotFoundException("No entry for " + uri);
}
throw new FileNotFoundException("Multiple items at " + uri);
}
c.moveToFirst();
int i = c.getColumnIndex("_data");
String path = (i >= 0 ? c.getString(i) : null);
c.close();
if (path == null) {
throw new FileNotFoundException("Column _data not found.");
}
int modeBits = ContentResolver.modeToMode(uri, mode);
return ParcelFileDescriptor.open(new File(path), modeBits);
}
/**
* Get the sync adapter that is to be used by this content provider.
* This is intended for use by the sync system. If null then this
* content provider is considered not syncable.
* This method can be called from multiple
* threads, as described in
* <a href="{@docRoot}guide/topics/fundamentals.html#procthread">Application Fundamentals:
* Processes and Threads</a>.
*
* @return the SyncAdapter that is to be used by this ContentProvider, or null
* if this ContentProvider is not syncable
* @hide
*/
public SyncAdapter getSyncAdapter() {
return null;
}
/**
* Returns true if this instance is a temporary content provider.
* @return true if this instance is a temporary content provider
*/
protected boolean isTemporary() {
return false;
}
/**
* Returns the Binder object for this provider.
*
* @return the Binder object for this provider
* @hide
*/
public IContentProvider getIContentProvider() {
return mTransport;
}
/**
* After being instantiated, this is called to tell the content provider
* about itself.
*
* @param context The context this provider is running in
* @param info Registered information about this content provider
*/
public void attachInfo(Context context, ProviderInfo info) {
/*
* Only allow it to be set once, so after the content service gives
* this to us clients can't change it.
*/
if (mContext == null) {
mContext = context;
if (info != null) {
setReadPermission(info.readPermission);
setWritePermission(info.writePermission);
}
ContentProvider.this.onCreate();
}
}
}
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