SQLiteQueryBuilder.java revision e5360fbf3efe85427f7e7f59afe7bbeddb4949ac
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.Cursor; 20import android.database.DatabaseUtils; 21import android.provider.BaseColumns; 22import android.text.TextUtils; 23import android.util.Log; 24 25import java.util.Iterator; 26import java.util.Map; 27import java.util.Map.Entry; 28import java.util.Set; 29import java.util.regex.Pattern; 30 31/** 32 * This is a convience class that helps build SQL queries to be sent to 33 * {@link SQLiteDatabase} objects. 34 */ 35public class SQLiteQueryBuilder 36{ 37 private static final String TAG = "SQLiteQueryBuilder"; 38 private static final Pattern sLimitPattern = 39 Pattern.compile("\\s*\\d+\\s*(,\\s*\\d+\\s*)?"); 40 41 private Map<String, String> mProjectionMap = null; 42 private String mTables = ""; 43 private StringBuilder mWhereClause = null; // lazily created 44 private boolean mDistinct; 45 private SQLiteDatabase.CursorFactory mFactory; 46 private boolean mStrict; 47 48 public SQLiteQueryBuilder() { 49 mDistinct = false; 50 mFactory = null; 51 } 52 53 /** 54 * Mark the query as DISTINCT. 55 * 56 * @param distinct if true the query is DISTINCT, otherwise it isn't 57 */ 58 public void setDistinct(boolean distinct) { 59 mDistinct = distinct; 60 } 61 62 /** 63 * Returns the list of tables being queried 64 * 65 * @return the list of tables being queried 66 */ 67 public String getTables() { 68 return mTables; 69 } 70 71 /** 72 * Sets the list of tables to query. Multiple tables can be specified to perform a join. 73 * For example: 74 * setTables("foo, bar") 75 * setTables("foo LEFT OUTER JOIN bar ON (foo.id = bar.foo_id)") 76 * 77 * @param inTables the list of tables to query on 78 */ 79 public void setTables(String inTables) { 80 mTables = inTables; 81 } 82 83 /** 84 * Append a chunk to the WHERE clause of the query. All chunks appended are surrounded 85 * by parenthesis and ANDed with the selection passed to {@link #query}. The final 86 * WHERE clause looks like: 87 * 88 * WHERE (<append chunk 1><append chunk2>) AND (<query() selection parameter>) 89 * 90 * @param inWhere the chunk of text to append to the WHERE clause. 91 */ 92 public void appendWhere(CharSequence inWhere) { 93 if (mWhereClause == null) { 94 mWhereClause = new StringBuilder(inWhere.length() + 16); 95 } 96 if (mWhereClause.length() == 0) { 97 mWhereClause.append('('); 98 } 99 mWhereClause.append(inWhere); 100 } 101 102 /** 103 * Append a chunk to the WHERE clause of the query. All chunks appended are surrounded 104 * by parenthesis and ANDed with the selection passed to {@link #query}. The final 105 * WHERE clause looks like: 106 * 107 * WHERE (<append chunk 1><append chunk2>) AND (<query() selection parameter>) 108 * 109 * @param inWhere the chunk of text to append to the WHERE clause. it will be escaped 110 * to avoid SQL injection attacks 111 */ 112 public void appendWhereEscapeString(String inWhere) { 113 if (mWhereClause == null) { 114 mWhereClause = new StringBuilder(inWhere.length() + 16); 115 } 116 if (mWhereClause.length() == 0) { 117 mWhereClause.append('('); 118 } 119 DatabaseUtils.appendEscapedSQLString(mWhereClause, inWhere); 120 } 121 122 /** 123 * Sets the projection map for the query. The projection map maps 124 * from column names that the caller passes into query to database 125 * column names. This is useful for renaming columns as well as 126 * disambiguating column names when doing joins. For example you 127 * could map "name" to "people.name". If a projection map is set 128 * it must contain all column names the user may request, even if 129 * the key and value are the same. 130 * 131 * @param columnMap maps from the user column names to the database column names 132 */ 133 public void setProjectionMap(Map<String, String> columnMap) { 134 mProjectionMap = columnMap; 135 } 136 137 /** 138 * Sets the cursor factory to be used for the query. You can use 139 * one factory for all queries on a database but it is normally 140 * easier to specify the factory when doing this query. @param 141 * factory the factor to use 142 */ 143 public void setCursorFactory(SQLiteDatabase.CursorFactory factory) { 144 mFactory = factory; 145 } 146 147 /** 148 * When set, the selection is verified against malicious arguments. 149 * When using this class to create a statement using 150 * {@link #buildQueryString(boolean, String, String[], String, String, String, String, String)}, 151 * non-numeric limits will raise an exception. If a projection map is specified, fields 152 * not in that map will be ignored. 153 * If this class is used to execute the statement directly using 154 * {@link #query(SQLiteDatabase, String[], String, String[], String, String, String)} 155 * or 156 * {@link #query(SQLiteDatabase, String[], String, String[], String, String, String, String)}, 157 * additionally also parenthesis escaping selection are caught. 158 * 159 * To summarize: To get maximum protection against malicious third party apps (for example 160 * content provider consumers), make sure to do the following: 161 * <ul> 162 * <li>Set this value to true</li> 163 * <li>Use a projection map</li> 164 * <li>Use one of the query overloads instead of getting the statement as a sql string</li> 165 * </ul> 166 * By default, this value is false. 167 */ 168 public void setStrict(boolean flag) { 169 mStrict = flag; 170 } 171 172 /** 173 * Build an SQL query string from the given clauses. 174 * 175 * @param distinct true if you want each row to be unique, false otherwise. 176 * @param tables The table names to compile the query against. 177 * @param columns A list of which columns to return. Passing null will 178 * return all columns, which is discouraged to prevent reading 179 * data from storage that isn't going to be used. 180 * @param where A filter declaring which rows to return, formatted as an SQL 181 * WHERE clause (excluding the WHERE itself). Passing null will 182 * return all rows for the given URL. 183 * @param groupBy A filter declaring how to group rows, formatted as an SQL 184 * GROUP BY clause (excluding the GROUP BY itself). Passing null 185 * will cause the rows to not be grouped. 186 * @param having A filter declare which row groups to include in the cursor, 187 * if row grouping is being used, formatted as an SQL HAVING 188 * clause (excluding the HAVING itself). Passing null will cause 189 * all row groups to be included, and is required when row 190 * grouping is not being used. 191 * @param orderBy How to order the rows, formatted as an SQL ORDER BY clause 192 * (excluding the ORDER BY itself). Passing null will use the 193 * default sort order, which may be unordered. 194 * @param limit Limits the number of rows returned by the query, 195 * formatted as LIMIT clause. Passing null denotes no LIMIT clause. 196 * @return the SQL query string 197 */ 198 public static String buildQueryString( 199 boolean distinct, String tables, String[] columns, String where, 200 String groupBy, String having, String orderBy, String limit) { 201 if (TextUtils.isEmpty(groupBy) && !TextUtils.isEmpty(having)) { 202 throw new IllegalArgumentException( 203 "HAVING clauses are only permitted when using a groupBy clause"); 204 } 205 if (!TextUtils.isEmpty(limit) && !sLimitPattern.matcher(limit).matches()) { 206 throw new IllegalArgumentException("invalid LIMIT clauses:" + limit); 207 } 208 209 StringBuilder query = new StringBuilder(120); 210 211 query.append("SELECT "); 212 if (distinct) { 213 query.append("DISTINCT "); 214 } 215 if (columns != null && columns.length != 0) { 216 appendColumns(query, columns); 217 } else { 218 query.append("* "); 219 } 220 query.append("FROM "); 221 query.append(tables); 222 appendClause(query, " WHERE ", where); 223 appendClause(query, " GROUP BY ", groupBy); 224 appendClause(query, " HAVING ", having); 225 appendClause(query, " ORDER BY ", orderBy); 226 appendClause(query, " LIMIT ", limit); 227 228 return query.toString(); 229 } 230 231 private static void appendClause(StringBuilder s, String name, String clause) { 232 if (!TextUtils.isEmpty(clause)) { 233 s.append(name); 234 s.append(clause); 235 } 236 } 237 238 /** 239 * Add the names that are non-null in columns to s, separating 240 * them with commas. 241 */ 242 public static void appendColumns(StringBuilder s, String[] columns) { 243 int n = columns.length; 244 245 for (int i = 0; i < n; i++) { 246 String column = columns[i]; 247 248 if (column != null) { 249 if (i > 0) { 250 s.append(", "); 251 } 252 s.append(column); 253 } 254 } 255 s.append(' '); 256 } 257 258 /** 259 * Perform a query by combining all current settings and the 260 * information passed into this method. 261 * 262 * @param db the database to query on 263 * @param projectionIn A list of which columns to return. Passing 264 * null will return all columns, which is discouraged to prevent 265 * reading data from storage that isn't going to be used. 266 * @param selection A filter declaring which rows to return, 267 * formatted as an SQL WHERE clause (excluding the WHERE 268 * itself). Passing null will return all rows for the given URL. 269 * @param selectionArgs You may include ?s in selection, which 270 * will be replaced by the values from selectionArgs, in order 271 * that they appear in the selection. The values will be bound 272 * as Strings. 273 * @param groupBy A filter declaring how to group rows, formatted 274 * as an SQL GROUP BY clause (excluding the GROUP BY 275 * itself). Passing null will cause the rows to not be grouped. 276 * @param having A filter declare which row groups to include in 277 * the cursor, if row grouping is being used, formatted as an 278 * SQL HAVING clause (excluding the HAVING itself). Passing 279 * null will cause all row groups to be included, and is 280 * required when row grouping is not being used. 281 * @param sortOrder How to order the rows, formatted as an SQL 282 * ORDER BY clause (excluding the ORDER BY itself). Passing null 283 * will use the default sort order, which may be unordered. 284 * @return a cursor over the result set 285 * @see android.content.ContentResolver#query(android.net.Uri, String[], 286 * String, String[], String) 287 */ 288 public Cursor query(SQLiteDatabase db, String[] projectionIn, 289 String selection, String[] selectionArgs, String groupBy, 290 String having, String sortOrder) { 291 return query(db, projectionIn, selection, selectionArgs, groupBy, having, sortOrder, 292 null /* limit */); 293 } 294 295 /** 296 * Perform a query by combining all current settings and the 297 * information passed into this method. 298 * 299 * @param db the database to query on 300 * @param projectionIn A list of which columns to return. Passing 301 * null will return all columns, which is discouraged to prevent 302 * reading data from storage that isn't going to be used. 303 * @param selection A filter declaring which rows to return, 304 * formatted as an SQL WHERE clause (excluding the WHERE 305 * itself). Passing null will return all rows for the given URL. 306 * @param selectionArgs You may include ?s in selection, which 307 * will be replaced by the values from selectionArgs, in order 308 * that they appear in the selection. The values will be bound 309 * as Strings. 310 * @param groupBy A filter declaring how to group rows, formatted 311 * as an SQL GROUP BY clause (excluding the GROUP BY 312 * itself). Passing null will cause the rows to not be grouped. 313 * @param having A filter declare which row groups to include in 314 * the cursor, if row grouping is being used, formatted as an 315 * SQL HAVING clause (excluding the HAVING itself). Passing 316 * null will cause all row groups to be included, and is 317 * required when row grouping is not being used. 318 * @param sortOrder How to order the rows, formatted as an SQL 319 * ORDER BY clause (excluding the ORDER BY itself). Passing null 320 * will use the default sort order, which may be unordered. 321 * @param limit Limits the number of rows returned by the query, 322 * formatted as LIMIT clause. Passing null denotes no LIMIT clause. 323 * @return a cursor over the result set 324 * @see android.content.ContentResolver#query(android.net.Uri, String[], 325 * String, String[], String) 326 */ 327 public Cursor query(SQLiteDatabase db, String[] projectionIn, 328 String selection, String[] selectionArgs, String groupBy, 329 String having, String sortOrder, String limit) { 330 if (mTables == null) { 331 return null; 332 } 333 334 if (mStrict && selection != null && selection.length() > 0) { 335 // Validate the user-supplied selection to detect syntactic anomalies 336 // in the selection string that could indicate a SQL injection attempt. 337 // The idea is to ensure that the selection clause is a valid SQL expression 338 // by compiling it twice: once wrapped in parentheses and once as 339 // originally specified. An attacker cannot create an expression that 340 // would escape the SQL expression while maintaining balanced parentheses 341 // in both the wrapped and original forms. 342 String sqlForValidation = buildQuery(projectionIn, "(" + selection + ")", groupBy, 343 having, sortOrder, limit); 344 validateQuerySql(db, sqlForValidation); // will throw if query is invalid 345 } 346 347 String sql = buildQuery( 348 projectionIn, selection, groupBy, having, 349 sortOrder, limit); 350 351 if (Log.isLoggable(TAG, Log.DEBUG)) { 352 Log.d(TAG, "Performing query: " + sql); 353 } 354 return db.rawQueryWithFactory( 355 mFactory, sql, selectionArgs, 356 SQLiteDatabase.findEditTable(mTables)); // will throw if query is invalid 357 } 358 359 /** 360 * Verifies that a SQL SELECT statement is valid by compiling it. 361 * If the SQL statement is not valid, this method will throw a {@link SQLiteException}. 362 */ 363 private void validateQuerySql(SQLiteDatabase db, String sql) { 364 db.getThreadSession().prepare(sql, 365 db.getThreadDefaultConnectionFlags(true /*readOnly*/), null); 366 } 367 368 /** 369 * Construct a SELECT statement suitable for use in a group of 370 * SELECT statements that will be joined through UNION operators 371 * in buildUnionQuery. 372 * 373 * @param projectionIn A list of which columns to return. Passing 374 * null will return all columns, which is discouraged to 375 * prevent reading data from storage that isn't going to be 376 * used. 377 * @param selection A filter declaring which rows to return, 378 * formatted as an SQL WHERE clause (excluding the WHERE 379 * itself). Passing null will return all rows for the given 380 * URL. 381 * @param groupBy A filter declaring how to group rows, formatted 382 * as an SQL GROUP BY clause (excluding the GROUP BY itself). 383 * Passing null will cause the rows to not be grouped. 384 * @param having A filter declare which row groups to include in 385 * the cursor, if row grouping is being used, formatted as an 386 * SQL HAVING clause (excluding the HAVING itself). Passing 387 * null will cause all row groups to be included, and is 388 * required when row grouping is not being used. 389 * @param sortOrder How to order the rows, formatted as an SQL 390 * ORDER BY clause (excluding the ORDER BY itself). Passing null 391 * will use the default sort order, which may be unordered. 392 * @param limit Limits the number of rows returned by the query, 393 * formatted as LIMIT clause. Passing null denotes no LIMIT clause. 394 * @return the resulting SQL SELECT statement 395 */ 396 public String buildQuery( 397 String[] projectionIn, String selection, String groupBy, 398 String having, String sortOrder, String limit) { 399 String[] projection = computeProjection(projectionIn); 400 401 StringBuilder where = new StringBuilder(); 402 boolean hasBaseWhereClause = mWhereClause != null && mWhereClause.length() > 0; 403 404 if (hasBaseWhereClause) { 405 where.append(mWhereClause.toString()); 406 where.append(')'); 407 } 408 409 // Tack on the user's selection, if present. 410 if (selection != null && selection.length() > 0) { 411 if (hasBaseWhereClause) { 412 where.append(" AND "); 413 } 414 415 where.append('('); 416 where.append(selection); 417 where.append(')'); 418 } 419 420 return buildQueryString( 421 mDistinct, mTables, projection, where.toString(), 422 groupBy, having, sortOrder, limit); 423 } 424 425 /** 426 * @deprecated This method's signature is misleading since no SQL parameter 427 * substitution is carried out. The selection arguments parameter does not get 428 * used at all. To avoid confusion, call 429 * {@link #buildQuery(String[], String, String, String, String, String)} instead. 430 */ 431 @Deprecated 432 public String buildQuery( 433 String[] projectionIn, String selection, String[] selectionArgs, 434 String groupBy, String having, String sortOrder, String limit) { 435 return buildQuery(projectionIn, selection, groupBy, having, sortOrder, limit); 436 } 437 438 /** 439 * Construct a SELECT statement suitable for use in a group of 440 * SELECT statements that will be joined through UNION operators 441 * in buildUnionQuery. 442 * 443 * @param typeDiscriminatorColumn the name of the result column 444 * whose cells will contain the name of the table from which 445 * each row was drawn. 446 * @param unionColumns the names of the columns to appear in the 447 * result. This may include columns that do not appear in the 448 * table this SELECT is querying (i.e. mTables), but that do 449 * appear in one of the other tables in the UNION query that we 450 * are constructing. 451 * @param columnsPresentInTable a Set of the names of the columns 452 * that appear in this table (i.e. in the table whose name is 453 * mTables). Since columns in unionColumns include columns that 454 * appear only in other tables, we use this array to distinguish 455 * which ones actually are present. Other columns will have 456 * NULL values for results from this subquery. 457 * @param computedColumnsOffset all columns in unionColumns before 458 * this index are included under the assumption that they're 459 * computed and therefore won't appear in columnsPresentInTable, 460 * e.g. "date * 1000 as normalized_date" 461 * @param typeDiscriminatorValue the value used for the 462 * type-discriminator column in this subquery 463 * @param selection A filter declaring which rows to return, 464 * formatted as an SQL WHERE clause (excluding the WHERE 465 * itself). Passing null will return all rows for the given 466 * URL. 467 * @param groupBy A filter declaring how to group rows, formatted 468 * as an SQL GROUP BY clause (excluding the GROUP BY itself). 469 * Passing null will cause the rows to not be grouped. 470 * @param having A filter declare which row groups to include in 471 * the cursor, if row grouping is being used, formatted as an 472 * SQL HAVING clause (excluding the HAVING itself). Passing 473 * null will cause all row groups to be included, and is 474 * required when row grouping is not being used. 475 * @return the resulting SQL SELECT statement 476 */ 477 public String buildUnionSubQuery( 478 String typeDiscriminatorColumn, 479 String[] unionColumns, 480 Set<String> columnsPresentInTable, 481 int computedColumnsOffset, 482 String typeDiscriminatorValue, 483 String selection, 484 String groupBy, 485 String having) { 486 int unionColumnsCount = unionColumns.length; 487 String[] projectionIn = new String[unionColumnsCount]; 488 489 for (int i = 0; i < unionColumnsCount; i++) { 490 String unionColumn = unionColumns[i]; 491 492 if (unionColumn.equals(typeDiscriminatorColumn)) { 493 projectionIn[i] = "'" + typeDiscriminatorValue + "' AS " 494 + typeDiscriminatorColumn; 495 } else if (i <= computedColumnsOffset 496 || columnsPresentInTable.contains(unionColumn)) { 497 projectionIn[i] = unionColumn; 498 } else { 499 projectionIn[i] = "NULL AS " + unionColumn; 500 } 501 } 502 return buildQuery( 503 projectionIn, selection, groupBy, having, 504 null /* sortOrder */, 505 null /* limit */); 506 } 507 508 /** 509 * @deprecated This method's signature is misleading since no SQL parameter 510 * substitution is carried out. The selection arguments parameter does not get 511 * used at all. To avoid confusion, call 512 * {@link #buildUnionSubQuery} 513 * instead. 514 */ 515 @Deprecated 516 public String buildUnionSubQuery( 517 String typeDiscriminatorColumn, 518 String[] unionColumns, 519 Set<String> columnsPresentInTable, 520 int computedColumnsOffset, 521 String typeDiscriminatorValue, 522 String selection, 523 String[] selectionArgs, 524 String groupBy, 525 String having) { 526 return buildUnionSubQuery( 527 typeDiscriminatorColumn, unionColumns, columnsPresentInTable, 528 computedColumnsOffset, typeDiscriminatorValue, selection, 529 groupBy, having); 530 } 531 532 /** 533 * Given a set of subqueries, all of which are SELECT statements, 534 * construct a query that returns the union of what those 535 * subqueries return. 536 * @param subQueries an array of SQL SELECT statements, all of 537 * which must have the same columns as the same positions in 538 * their results 539 * @param sortOrder How to order the rows, formatted as an SQL 540 * ORDER BY clause (excluding the ORDER BY itself). Passing 541 * null will use the default sort order, which may be unordered. 542 * @param limit The limit clause, which applies to the entire union result set 543 * 544 * @return the resulting SQL SELECT statement 545 */ 546 public String buildUnionQuery(String[] subQueries, String sortOrder, String limit) { 547 StringBuilder query = new StringBuilder(128); 548 int subQueryCount = subQueries.length; 549 String unionOperator = mDistinct ? " UNION " : " UNION ALL "; 550 551 for (int i = 0; i < subQueryCount; i++) { 552 if (i > 0) { 553 query.append(unionOperator); 554 } 555 query.append(subQueries[i]); 556 } 557 appendClause(query, " ORDER BY ", sortOrder); 558 appendClause(query, " LIMIT ", limit); 559 return query.toString(); 560 } 561 562 private String[] computeProjection(String[] projectionIn) { 563 if (projectionIn != null && projectionIn.length > 0) { 564 if (mProjectionMap != null) { 565 String[] projection = new String[projectionIn.length]; 566 int length = projectionIn.length; 567 568 for (int i = 0; i < length; i++) { 569 String userColumn = projectionIn[i]; 570 String column = mProjectionMap.get(userColumn); 571 572 if (column != null) { 573 projection[i] = column; 574 continue; 575 } 576 577 if (!mStrict && 578 ( userColumn.contains(" AS ") || userColumn.contains(" as "))) { 579 /* A column alias already exist */ 580 projection[i] = userColumn; 581 continue; 582 } 583 584 throw new IllegalArgumentException("Invalid column " 585 + projectionIn[i]); 586 } 587 return projection; 588 } else { 589 return projectionIn; 590 } 591 } else if (mProjectionMap != null) { 592 // Return all columns in projection map. 593 Set<Entry<String, String>> entrySet = mProjectionMap.entrySet(); 594 String[] projection = new String[entrySet.size()]; 595 Iterator<Entry<String, String>> entryIter = entrySet.iterator(); 596 int i = 0; 597 598 while (entryIter.hasNext()) { 599 Entry<String, String> entry = entryIter.next(); 600 601 // Don't include the _count column when people ask for no projection. 602 if (entry.getKey().equals(BaseColumns._COUNT)) { 603 continue; 604 } 605 projection[i++] = entry.getValue(); 606 } 607 return projection; 608 } 609 return null; 610 } 611} 612