SQLiteCursor.java revision ebc016c01ea9d5707287cfc19ccc59b21a486c00
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 for (int i = 0; i < mColumns.length; i++) { 109 // Make note of the row ID column index for quick access to it 110 if ("_id".equals(mColumns[i])) { 111 mRowIdColumnIndex = i; 112 } 113 } 114 } 115 116 /** 117 * Get the database that this cursor is associated with. 118 * @return the SQLiteDatabase that this cursor is associated with. 119 */ 120 public SQLiteDatabase getDatabase() { 121 return mQuery.getDatabase(); 122 } 123 124 @Override 125 public boolean onMove(int oldPosition, int newPosition) { 126 // Make sure the row at newPosition is present in the window 127 if (mWindow == null || newPosition < mWindow.getStartPosition() || 128 newPosition >= (mWindow.getStartPosition() + mWindow.getNumRows())) { 129 fillWindow(newPosition); 130 } 131 132 return true; 133 } 134 135 @Override 136 public int getCount() { 137 if (mCount == NO_COUNT) { 138 fillWindow(0); 139 } 140 return mCount; 141 } 142 143 private void fillWindow(int requiredPos) { 144 clearOrCreateWindow(getDatabase().getPath()); 145 146 if (mCount == NO_COUNT) { 147 int startPos = DatabaseUtils.cursorPickFillWindowStartPosition(requiredPos, 0); 148 mCount = mQuery.fillWindow(mWindow, startPos, requiredPos, true); 149 mCursorWindowCapacity = mWindow.getNumRows(); 150 if (Log.isLoggable(TAG, Log.DEBUG)) { 151 Log.d(TAG, "received count(*) from native_fill_window: " + mCount); 152 } 153 } else { 154 int startPos = DatabaseUtils.cursorPickFillWindowStartPosition(requiredPos, 155 mCursorWindowCapacity); 156 mQuery.fillWindow(mWindow, startPos, requiredPos, false); 157 } 158 } 159 160 @Override 161 public int getColumnIndex(String columnName) { 162 // Create mColumnNameMap on demand 163 if (mColumnNameMap == null) { 164 String[] columns = mColumns; 165 int columnCount = columns.length; 166 HashMap<String, Integer> map = new HashMap<String, Integer>(columnCount, 1); 167 for (int i = 0; i < columnCount; i++) { 168 map.put(columns[i], i); 169 } 170 mColumnNameMap = map; 171 } 172 173 // Hack according to bug 903852 174 final int periodIndex = columnName.lastIndexOf('.'); 175 if (periodIndex != -1) { 176 Exception e = new Exception(); 177 Log.e(TAG, "requesting column name with table name -- " + columnName, e); 178 columnName = columnName.substring(periodIndex + 1); 179 } 180 181 Integer i = mColumnNameMap.get(columnName); 182 if (i != null) { 183 return i.intValue(); 184 } else { 185 return -1; 186 } 187 } 188 189 @Override 190 public String[] getColumnNames() { 191 return mColumns; 192 } 193 194 @Override 195 public void deactivate() { 196 super.deactivate(); 197 mDriver.cursorDeactivated(); 198 } 199 200 @Override 201 public void close() { 202 super.close(); 203 synchronized (this) { 204 mQuery.close(); 205 mDriver.cursorClosed(); 206 } 207 } 208 209 @Override 210 public boolean requery() { 211 if (isClosed()) { 212 return false; 213 } 214 215 synchronized (this) { 216 if (!mQuery.getDatabase().isOpen()) { 217 return false; 218 } 219 220 if (mWindow != null) { 221 mWindow.clear(); 222 } 223 mPos = -1; 224 mCount = NO_COUNT; 225 226 mDriver.cursorRequeried(this); 227 } 228 229 try { 230 return super.requery(); 231 } catch (IllegalStateException e) { 232 // for backwards compatibility, just return false 233 Log.w(TAG, "requery() failed " + e.getMessage(), e); 234 return false; 235 } 236 } 237 238 @Override 239 public void setWindow(CursorWindow window) { 240 super.setWindow(window); 241 mCount = NO_COUNT; 242 } 243 244 /** 245 * Changes the selection arguments. The new values take effect after a call to requery(). 246 */ 247 public void setSelectionArguments(String[] selectionArgs) { 248 mDriver.setBindArguments(selectionArgs); 249 } 250 251 /** 252 * Release the native resources, if they haven't been released yet. 253 */ 254 @Override 255 protected void finalize() { 256 try { 257 // if the cursor hasn't been closed yet, close it first 258 if (mWindow != null) { 259 if (mStackTrace != null) { 260 String sql = mQuery.getSql(); 261 int len = sql.length(); 262 StrictMode.onSqliteObjectLeaked( 263 "Finalizing a Cursor that has not been deactivated or closed. " + 264 "database = " + mQuery.getDatabase().getLabel() + 265 ", table = " + mEditTable + 266 ", query = " + sql.substring(0, (len > 1000) ? 1000 : len), 267 mStackTrace); 268 } 269 close(); 270 } 271 } finally { 272 super.finalize(); 273 } 274 } 275} 276