1/* 2 * Copyright (C) 2006 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17package android.database.sqlite; 18 19import android.database.AbstractWindowedCursor; 20import android.database.CursorWindow; 21import android.database.DatabaseUtils; 22import android.os.StrictMode; 23import android.util.Log; 24 25import java.util.HashMap; 26import java.util.Map; 27 28/** 29 * A Cursor implementation that exposes results from a query on a 30 * {@link SQLiteDatabase}. 31 * 32 * SQLiteCursor is not internally synchronized so code using a SQLiteCursor from multiple 33 * threads should perform its own synchronization when using the SQLiteCursor. 34 */ 35public class SQLiteCursor extends AbstractWindowedCursor { 36 static final String TAG = "SQLiteCursor"; 37 static final int NO_COUNT = -1; 38 39 /** The name of the table to edit */ 40 private final String mEditTable; 41 42 /** The names of the columns in the rows */ 43 private final String[] mColumns; 44 45 /** The query object for the cursor */ 46 private final SQLiteQuery mQuery; 47 48 /** The compiled query this cursor came from */ 49 private final SQLiteCursorDriver mDriver; 50 51 /** The number of rows in the cursor */ 52 private int mCount = NO_COUNT; 53 54 /** The number of rows that can fit in the cursor window, 0 if unknown */ 55 private int mCursorWindowCapacity; 56 57 /** A mapping of column names to column indices, to speed up lookups */ 58 private Map<String, Integer> mColumnNameMap; 59 60 /** Used to find out where a cursor was allocated in case it never got released. */ 61 private final Throwable mStackTrace; 62 63 /** 64 * Execute a query and provide access to its result set through a Cursor 65 * interface. For a query such as: {@code SELECT name, birth, phone FROM 66 * myTable WHERE ... LIMIT 1,20 ORDER BY...} the column names (name, birth, 67 * phone) would be in the projection argument and everything from 68 * {@code FROM} onward would be in the params argument. 69 * 70 * @param db a reference to a Database object that is already constructed 71 * and opened. This param is not used any longer 72 * @param editTable the name of the table used for this query 73 * @param query the rest of the query terms 74 * cursor is finalized 75 * @deprecated use {@link #SQLiteCursor(SQLiteCursorDriver, String, SQLiteQuery)} instead 76 */ 77 @Deprecated 78 public SQLiteCursor(SQLiteDatabase db, SQLiteCursorDriver driver, 79 String editTable, SQLiteQuery query) { 80 this(driver, editTable, query); 81 } 82 83 /** 84 * Execute a query and provide access to its result set through a Cursor 85 * interface. For a query such as: {@code SELECT name, birth, phone FROM 86 * myTable WHERE ... LIMIT 1,20 ORDER BY...} the column names (name, birth, 87 * phone) would be in the projection argument and everything from 88 * {@code FROM} onward would be in the params argument. 89 * 90 * @param editTable the name of the table used for this query 91 * @param query the {@link SQLiteQuery} object associated with this cursor object. 92 */ 93 public SQLiteCursor(SQLiteCursorDriver driver, String editTable, SQLiteQuery query) { 94 if (query == null) { 95 throw new IllegalArgumentException("query object cannot be null"); 96 } 97 if (StrictMode.vmSqliteObjectLeaksEnabled()) { 98 mStackTrace = new DatabaseObjectNotClosedException().fillInStackTrace(); 99 } else { 100 mStackTrace = null; 101 } 102 mDriver = driver; 103 mEditTable = editTable; 104 mColumnNameMap = null; 105 mQuery = query; 106 107 mColumns = query.getColumnNames(); 108 mRowIdColumnIndex = DatabaseUtils.findRowIdColumnIndex(mColumns); 109 } 110 111 /** 112 * Get the database that this cursor is associated with. 113 * @return the SQLiteDatabase that this cursor is associated with. 114 */ 115 public SQLiteDatabase getDatabase() { 116 return mQuery.getDatabase(); 117 } 118 119 @Override 120 public boolean onMove(int oldPosition, int newPosition) { 121 // Make sure the row at newPosition is present in the window 122 if (mWindow == null || newPosition < mWindow.getStartPosition() || 123 newPosition >= (mWindow.getStartPosition() + mWindow.getNumRows())) { 124 fillWindow(newPosition); 125 } 126 127 return true; 128 } 129 130 @Override 131 public int getCount() { 132 if (mCount == NO_COUNT) { 133 fillWindow(0); 134 } 135 return mCount; 136 } 137 138 private void fillWindow(int requiredPos) { 139 clearOrCreateWindow(getDatabase().getPath()); 140 141 if (mCount == NO_COUNT) { 142 int startPos = DatabaseUtils.cursorPickFillWindowStartPosition(requiredPos, 0); 143 mCount = mQuery.fillWindow(mWindow, startPos, requiredPos, true); 144 mCursorWindowCapacity = mWindow.getNumRows(); 145 if (Log.isLoggable(TAG, Log.DEBUG)) { 146 Log.d(TAG, "received count(*) from native_fill_window: " + mCount); 147 } 148 } else { 149 int startPos = DatabaseUtils.cursorPickFillWindowStartPosition(requiredPos, 150 mCursorWindowCapacity); 151 mQuery.fillWindow(mWindow, startPos, requiredPos, false); 152 } 153 } 154 155 @Override 156 public int getColumnIndex(String columnName) { 157 // Create mColumnNameMap on demand 158 if (mColumnNameMap == null) { 159 String[] columns = mColumns; 160 int columnCount = columns.length; 161 HashMap<String, Integer> map = new HashMap<String, Integer>(columnCount, 1); 162 for (int i = 0; i < columnCount; i++) { 163 map.put(columns[i], i); 164 } 165 mColumnNameMap = map; 166 } 167 168 // Hack according to bug 903852 169 final int periodIndex = columnName.lastIndexOf('.'); 170 if (periodIndex != -1) { 171 Exception e = new Exception(); 172 Log.e(TAG, "requesting column name with table name -- " + columnName, e); 173 columnName = columnName.substring(periodIndex + 1); 174 } 175 176 Integer i = mColumnNameMap.get(columnName); 177 if (i != null) { 178 return i.intValue(); 179 } else { 180 return -1; 181 } 182 } 183 184 @Override 185 public String[] getColumnNames() { 186 return mColumns; 187 } 188 189 @Override 190 public void deactivate() { 191 super.deactivate(); 192 mDriver.cursorDeactivated(); 193 } 194 195 @Override 196 public void close() { 197 super.close(); 198 synchronized (this) { 199 mQuery.close(); 200 mDriver.cursorClosed(); 201 } 202 } 203 204 @Override 205 public boolean requery() { 206 if (isClosed()) { 207 return false; 208 } 209 210 synchronized (this) { 211 if (!mQuery.getDatabase().isOpen()) { 212 return false; 213 } 214 215 if (mWindow != null) { 216 mWindow.clear(); 217 } 218 mPos = -1; 219 mCount = NO_COUNT; 220 221 mDriver.cursorRequeried(this); 222 } 223 224 try { 225 return super.requery(); 226 } catch (IllegalStateException e) { 227 // for backwards compatibility, just return false 228 Log.w(TAG, "requery() failed " + e.getMessage(), e); 229 return false; 230 } 231 } 232 233 @Override 234 public void setWindow(CursorWindow window) { 235 super.setWindow(window); 236 mCount = NO_COUNT; 237 } 238 239 /** 240 * Changes the selection arguments. The new values take effect after a call to requery(). 241 */ 242 public void setSelectionArguments(String[] selectionArgs) { 243 mDriver.setBindArguments(selectionArgs); 244 } 245 246 /** 247 * Release the native resources, if they haven't been released yet. 248 */ 249 @Override 250 protected void finalize() { 251 try { 252 // if the cursor hasn't been closed yet, close it first 253 if (mWindow != null) { 254 if (mStackTrace != null) { 255 String sql = mQuery.getSql(); 256 int len = sql.length(); 257 StrictMode.onSqliteObjectLeaked( 258 "Finalizing a Cursor that has not been deactivated or closed. " + 259 "database = " + mQuery.getDatabase().getLabel() + 260 ", table = " + mEditTable + 261 ", query = " + sql.substring(0, (len > 1000) ? 1000 : len), 262 mStackTrace); 263 } 264 close(); 265 } 266 } finally { 267 super.finalize(); 268 } 269 } 270} 271