/*
* 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.database.sqlite;
import android.database.AbstractWindowedCursor;
import android.database.CursorWindow;
import android.database.DatabaseUtils;
import android.os.StrictMode;
import android.util.Log;
import java.util.HashMap;
import java.util.Map;
/**
* A Cursor implementation that exposes results from a query on a
* {@link SQLiteDatabase}.
*
* SQLiteCursor is not internally synchronized so code using a SQLiteCursor from multiple
* threads should perform its own synchronization when using the SQLiteCursor.
*/
public class SQLiteCursor extends AbstractWindowedCursor {
static final String TAG = "SQLiteCursor";
static final int NO_COUNT = -1;
/** The name of the table to edit */
private final String mEditTable;
/** The names of the columns in the rows */
private final String[] mColumns;
/** The query object for the cursor */
private final SQLiteQuery mQuery;
/** The compiled query this cursor came from */
private final SQLiteCursorDriver mDriver;
/** The number of rows in the cursor */
private int mCount = NO_COUNT;
/** The number of rows that can fit in the cursor window, 0 if unknown */
private int mCursorWindowCapacity;
/** A mapping of column names to column indices, to speed up lookups */
private Map<String, Integer> mColumnNameMap;
/** Used to find out where a cursor was allocated in case it never got released. */
private final Throwable mStackTrace;
/**
* Execute a query and provide access to its result set through a Cursor
* interface. For a query such as: {@code SELECT name, birth, phone FROM
* myTable WHERE ... LIMIT 1,20 ORDER BY...} the column names (name, birth,
* phone) would be in the projection argument and everything from
* {@code FROM} onward would be in the params argument.
*
* @param db a reference to a Database object that is already constructed
* and opened. This param is not used any longer
* @param editTable the name of the table used for this query
* @param query the rest of the query terms
* cursor is finalized
* @deprecated use {@link #SQLiteCursor(SQLiteCursorDriver, String, SQLiteQuery)} instead
*/
@Deprecated
public SQLiteCursor(SQLiteDatabase db, SQLiteCursorDriver driver,
String editTable, SQLiteQuery query) {
this(driver, editTable, query);
}
/**
* Execute a query and provide access to its result set through a Cursor
* interface. For a query such as: {@code SELECT name, birth, phone FROM
* myTable WHERE ... LIMIT 1,20 ORDER BY...} the column names (name, birth,
* phone) would be in the projection argument and everything from
* {@code FROM} onward would be in the params argument.
*
* @param editTable the name of the table used for this query
* @param query the {@link SQLiteQuery} object associated with this cursor object.
*/
public SQLiteCursor(SQLiteCursorDriver driver, String editTable, SQLiteQuery query) {
if (query == null) {
throw new IllegalArgumentException("query object cannot be null");
}
if (StrictMode.vmSqliteObjectLeaksEnabled()) {
mStackTrace = new DatabaseObjectNotClosedException().fillInStackTrace();
} else {
mStackTrace = null;
}
mDriver = driver;
mEditTable = editTable;
mColumnNameMap = null;
mQuery = query;
mColumns = query.getColumnNames();
mRowIdColumnIndex = DatabaseUtils.findRowIdColumnIndex(mColumns);
}
/**
* Get the database that this cursor is associated with.
* @return the SQLiteDatabase that this cursor is associated with.
*/
public SQLiteDatabase getDatabase() {
return mQuery.getDatabase();
}
@Override
public boolean onMove(int oldPosition, int newPosition) {
// Make sure the row at newPosition is present in the window
if (mWindow == null || newPosition < mWindow.getStartPosition() ||
newPosition >= (mWindow.getStartPosition() + mWindow.getNumRows())) {
fillWindow(newPosition);
}
return true;
}
@Override
public int getCount() {
if (mCount == NO_COUNT) {
fillWindow(0);
}
return mCount;
}
private void fillWindow(int requiredPos) {
clearOrCreateWindow(getDatabase().getPath());
try {
if (mCount == NO_COUNT) {
int startPos = DatabaseUtils.cursorPickFillWindowStartPosition(requiredPos, 0);
mCount = mQuery.fillWindow(mWindow, startPos, requiredPos, true);
mCursorWindowCapacity = mWindow.getNumRows();
if (Log.isLoggable(TAG, Log.DEBUG)) {
Log.d(TAG, "received count(*) from native_fill_window: " + mCount);
}
} else {
int startPos = DatabaseUtils.cursorPickFillWindowStartPosition(requiredPos,
mCursorWindowCapacity);
mQuery.fillWindow(mWindow, startPos, requiredPos, false);
}
} catch (RuntimeException ex) {
// Close the cursor window if the query failed and therefore will
// not produce any results. This helps to avoid accidentally leaking
// the cursor window if the client does not correctly handle exceptions
// and fails to close the cursor.
closeWindow();
throw ex;
}
}
@Override
public int getColumnIndex(String columnName) {
// Create mColumnNameMap on demand
if (mColumnNameMap == null) {
String[] columns = mColumns;
int columnCount = columns.length;
HashMap<String, Integer> map = new HashMap<String, Integer>(columnCount, 1);
for (int i = 0; i < columnCount; i++) {
map.put(columns[i], i);
}
mColumnNameMap = map;
}
// Hack according to bug 903852
final int periodIndex = columnName.lastIndexOf('.');
if (periodIndex != -1) {
Exception e = new Exception();
Log.e(TAG, "requesting column name with table name -- " + columnName, e);
columnName = columnName.substring(periodIndex + 1);
}
Integer i = mColumnNameMap.get(columnName);
if (i != null) {
return i.intValue();
} else {
return -1;
}
}
@Override
public String[] getColumnNames() {
return mColumns;
}
@Override
public void deactivate() {
super.deactivate();
mDriver.cursorDeactivated();
}
@Override
public void close() {
super.close();
synchronized (this) {
mQuery.close();
mDriver.cursorClosed();
}
}
@Override
public boolean requery() {
if (isClosed()) {
return false;
}
synchronized (this) {
if (!mQuery.getDatabase().isOpen()) {
return false;
}
if (mWindow != null) {
mWindow.clear();
}
mPos = -1;
mCount = NO_COUNT;
mDriver.cursorRequeried(this);
}
try {
return super.requery();
} catch (IllegalStateException e) {
// for backwards compatibility, just return false
Log.w(TAG, "requery() failed " + e.getMessage(), e);
return false;
}
}
@Override
public void setWindow(CursorWindow window) {
super.setWindow(window);
mCount = NO_COUNT;
}
/**
* Changes the selection arguments. The new values take effect after a call to requery().
*/
public void setSelectionArguments(String[] selectionArgs) {
mDriver.setBindArguments(selectionArgs);
}
/**
* Release the native resources, if they haven't been released yet.
*/
@Override
protected void finalize() {
try {
// if the cursor hasn't been closed yet, close it first
if (mWindow != null) {
if (mStackTrace != null) {
String sql = mQuery.getSql();
int len = sql.length();
StrictMode.onSqliteObjectLeaked(
"Finalizing a Cursor that has not been deactivated or closed. " +
"database = " + mQuery.getDatabase().getLabel() +
", table = " + mEditTable +
", query = " + sql.substring(0, (len > 1000) ? 1000 : len),
mStackTrace);
}
close();
}
} finally {
super.finalize();
}
}
}
|
