我们将获得的Cursor对象交与Activity 来管理，这样Cursor对象的生命周期便能与当前的Activity自动同步，省去了自己管理Cursor。

 

public class NotesProvider extends ContentProvider {

 public static final String AUTHORITY = "com.example.android.honeypad.notesprovider";

 private static final String NOTE_MIME_TYPE = "vnd.android.cursor.item/vnd.honeypad.note";

 public static final Uri CONTENT_URI = Uri.parse("content://" + AUTHORITY

   + "/notes");

 // The underlying database

 private SQLiteDatabase notesDB;

 // Create the constants used to differentiate between the different URI

 // requests.

 private static final int ALL_NOTES = 1;

 private static final int NOTE_ID = 2;

 private static final UriMatcher uriMatcher;

 // Allocate the UriMatcher object, where a URI ending in 'notes' will

 // correspond to a request for all notes, and 'notes' with a trailing

 // '/[rowID]' will represent a single note row.

 static {

  uriMatcher = new UriMatcher(UriMatcher.NO_MATCH);

  uriMatcher.addURI(AUTHORITY, "notes", ALL_NOTES);

  uriMatcher.addURI(AUTHORITY, "notes/#", NOTE_ID);

 }

 @Override

 public boolean onCreate() {

  NotesDatabaseHelper helper = new NotesDatabaseHelper(getContext());

  notesDB = helper.getWritableDatabase();

  return notesDB != null;

 }

 @Override

 public Cursor query(Uri uri, String[] projection, String selection,

   String[] selectionArgs, String sort) {

  SQLiteQueryBuilder qb = new SQLiteQueryBuilder();

  qb.setTables(DATABASE_TABLE);

  // If this is a row query, limit the result set to the passed in row.

  switch (uriMatcher.match(uri)) {

  case NOTE_ID:

   qb.appendWhere(KEY_ID + "=" + uri.getPathSegments().get(1));

   break;

  default:

   break;

  }

  // Apply the query to the underlying database.

  Cursor c = qb.query(notesDB, projection, selection, selectionArgs,

    null, null, sort);

  // Register the contexts ContentResolver to be notified if

  // the cursor result set changes.

  c.setNotificationUri(getContext().getContentResolver(), uri);

  // Return a cursor to the query result.

  return c;

 }

 @Override

 public Uri insert(Uri uri, ContentValues initialValues) {

  // Insert the new row, will return the row number if

  // successful.

  long rowID = notesDB.insert(DATABASE_TABLE, "note", initialValues);

  // Return a URI to the newly inserted row on success.

  if (rowID > 0) {

   Uri newUri = ContentUris.withAppendedId(CONTENT_URI, rowID);

   getContext().getContentResolver().notifyChange(newUri, null);

   return newUri;

  }

  throw new SQLException("Failed to insert row into " + uri);

 }

 @Override

 public int delete(Uri uri, String where, String[] whereArgs) {

  int count;

  switch (uriMatcher.match(uri)) {

  case ALL_NOTES:

   count = notesDB.delete(DATABASE_TABLE, where, whereArgs);

   break;

  case NOTE_ID:

   String segment = uri.getPathSegments().get(1);

   StringBuilder whereClause = new StringBuilder(KEY_ID).append("=")

     .append(segment);

   if (!TextUtils.isEmpty(where)) {

    whereClause.append(" AND (").append(where).append(")");

   }

   count = notesDB.delete(DATABASE_TABLE, whereClause.toString(),

     whereArgs);

   break;

  default:

   throw new IllegalArgumentException("Unsupported URI: " + uri);

  }

  getContext().getContentResolver().notifyChange(uri, null);

  return count;

 }

 @Override

 public int update(Uri uri, ContentValues values, String where,

   String[] whereArgs) {

  int count;

  switch (uriMatcher.match(uri)) {

  case ALL_NOTES:

   count = notesDB.update(DATABASE_TABLE, values, where, whereArgs);

   break;

  case NOTE_ID:

   String segment = uri.getPathSegments().get(1);

   StringBuilder whereClause = new StringBuilder(KEY_ID).append("=")

     .append(segment);

   if (!TextUtils.isEmpty(where)) {

    whereClause.append(" AND (").append(where).append(")");

   }

   count = notesDB.update(DATABASE_TABLE, values,

     whereClause.toString(), whereArgs);

   break;

  default:

   throw new IllegalArgumentException("Unknown URI " + uri);

  }

  getContext().getContentResolver().notifyChange(uri, null);

  return count;

 }

 @Override

 public String getType(Uri uri) {

  switch (uriMatcher.match(uri)) {

  case ALL_NOTES:

   return "vnd.android.cursor.dir/vnd.honeypad.notes";

  case NOTE_ID:

   return NOTE_MIME_TYPE;

  default:

   throw new IllegalArgumentException("Unsupported URI: " + uri);

  }

 }

 // column names

 public static final String KEY_ID = "_id";

 public static final String KEY_TITLE = "title";

 public static final String KEY_BODY = "body";

 

 // column indexes

 public static final int ID_COLUMN = 0;

 public static final int TITLE_COLUMN = 1;

 public static final int BODY_COLUMN = 2;

 

 private static final String TAG = "NotesDbAdapter";

 private static final String DATABASE_NAME = "honeypad.db";

 private static final String DATABASE_TABLE = "notes";

 private static final int DATABASE_VERSION = 1;

 /**

  * Database creation sql statement

  */

 private static final String DATABASE_CREATE = String.format("create table %s (%s integer primary key autoincrement, %s text not null, %s text not null);",

   DATABASE_TABLE, KEY_ID, KEY_TITLE, KEY_BODY);

 private static class NotesDatabaseHelper extends SQLiteOpenHelper {

  NotesDatabaseHelper(Context context) {

   super(context, DATABASE_NAME, null, DATABASE_VERSION);

  }

  @Override

  public void onCreate(SQLiteDatabase db) {

   db.execSQL(DATABASE_CREATE);

  }

  @Override

  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

   Log.w(TAG, "Upgrading database from version " + oldVersion + " to "

     + newVersion + ", which will destroy all old data");

   db.execSQL("DROP TABLE IF EXISTS notes");

   onCreate(db);

  }

 }

 }