| 1 | /* |
| 2 | * Copyright 2006-2009 the original author or authors. |
| 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 | |
| 17 | package org.springframework.batch.item.database; |
| 18 | |
| 19 | import java.sql.Connection; |
| 20 | import java.sql.PreparedStatement; |
| 21 | import java.sql.ResultSet; |
| 22 | import java.sql.SQLException; |
| 23 | import java.sql.SQLWarning; |
| 24 | import java.sql.Statement; |
| 25 | |
| 26 | import javax.sql.DataSource; |
| 27 | |
| 28 | import org.apache.commons.logging.Log; |
| 29 | import org.apache.commons.logging.LogFactory; |
| 30 | import org.springframework.batch.item.ExecutionContext; |
| 31 | import org.springframework.batch.item.ItemStream; |
| 32 | import org.springframework.batch.item.ReaderNotOpenException; |
| 33 | import org.springframework.batch.item.support.AbstractItemCountingItemStreamItemReader; |
| 34 | import org.springframework.beans.factory.InitializingBean; |
| 35 | import org.springframework.dao.InvalidDataAccessApiUsageException; |
| 36 | import org.springframework.dao.InvalidDataAccessResourceUsageException; |
| 37 | import org.springframework.jdbc.SQLWarningException; |
| 38 | import org.springframework.jdbc.datasource.DataSourceUtils; |
| 39 | import org.springframework.jdbc.support.JdbcUtils; |
| 40 | import org.springframework.jdbc.support.SQLErrorCodeSQLExceptionTranslator; |
| 41 | import org.springframework.jdbc.support.SQLExceptionTranslator; |
| 42 | import org.springframework.jdbc.support.SQLStateSQLExceptionTranslator; |
| 43 | import org.springframework.transaction.support.TransactionSynchronizationManager; |
| 44 | import org.springframework.util.Assert; |
| 45 | |
| 46 | /** |
| 47 | * <p> |
| 48 | * Abstract base class for any simple item reader that opens a database cursor and continually retrieves |
| 49 | * the next row in the ResultSet. |
| 50 | * </p> |
| 51 | * |
| 52 | * <p> |
| 53 | * By default the cursor will be opened using a separate connection. The ResultSet for the cursor |
| 54 | * is held open regardless of commits or roll backs in a surrounding transaction. Clients of this |
| 55 | * reader are responsible for buffering the items in the case that they need to be re-presented on a |
| 56 | * rollback. This buffering is handled by the step implementations provided and is only a concern for |
| 57 | * anyone writing their own step implementations. |
| 58 | * </p> |
| 59 | * |
| 60 | * <p> |
| 61 | * There is an option ({@link #setUseSharedExtendedConnection(boolean)} that will share the connection |
| 62 | * used for the cursor with the rest of the step processing. If you set this flag to <code>true</code> |
| 63 | * then you must wrap the DataSource in a {@link ExtendedConnectionDataSourceProxy} to prevent the |
| 64 | * connection from being closed and released after each commit performed as part of the step processing. |
| 65 | * You must also use a JDBC driver supporting JDBC 3.0 or later since the cursor will be opened with the |
| 66 | * additional option of 'HOLD_CUSORS_OVER_COMMIT' enabled. |
| 67 | * </p> |
| 68 | * |
| 69 | * <p> |
| 70 | * Each call to {@link #read()} will attempt to map the row at the current position in the |
| 71 | * ResultSet. There is currently no wrapping of the ResultSet to suppress calls |
| 72 | * to next(). However, if the RowMapper (mistakenly) increments the current row, |
| 73 | * the next call to read will verify that the current row is at the expected |
| 74 | * position and throw a DataAccessException if it is not. The reason for such strictness on the |
| 75 | * ResultSet is due to the need to maintain control for transactions and |
| 76 | * restartability. This ensures that each call to {@link #read()} returns the |
| 77 | * ResultSet at the correct row, regardless of rollbacks or restarts. |
| 78 | * </p> |
| 79 | * |
| 80 | * <p> |
| 81 | * {@link ExecutionContext}: The current row is returned as restart data, and |
| 82 | * when restored from that same data, the cursor is opened and the current row |
| 83 | * set to the value within the restart data. See |
| 84 | * {@link #setDriverSupportsAbsolute(boolean)} for improving restart |
| 85 | * performance. |
| 86 | * </p> |
| 87 | * |
| 88 | * <p> |
| 89 | * Calling close on this {@link ItemStream} will cause all resources it is |
| 90 | * currently using to be freed. (Connection, ResultSet, etc). It is then illegal |
| 91 | * to call {@link #read()} again until it has been re-opened. |
| 92 | * </p> |
| 93 | * |
| 94 | * <p> |
| 95 | * Known limitation: when used with Derby |
| 96 | * {@link #setVerifyCursorPosition(boolean)} needs to be <code>false</code> |
| 97 | * because {@link ResultSet#getRow()} call used for cursor position verification |
| 98 | * is not available for 'TYPE_FORWARD_ONLY' result sets. |
| 99 | * </p> |
| 100 | * |
| 101 | * @author Lucas Ward |
| 102 | * @author Peter Zozom |
| 103 | * @author Robert Kasanicky |
| 104 | * @author Thomas Risberg |
| 105 | */ |
| 106 | public abstract class AbstractCursorItemReader<T> extends AbstractItemCountingItemStreamItemReader<T> |
| 107 | implements InitializingBean { |
| 108 | |
| 109 | /** Logger available to subclasses */ |
| 110 | protected final Log log = LogFactory.getLog(getClass()); |
| 111 | |
| 112 | public static final int VALUE_NOT_SET = -1; |
| 113 | private Connection con; |
| 114 | |
| 115 | protected ResultSet rs; |
| 116 | |
| 117 | private DataSource dataSource; |
| 118 | |
| 119 | private int fetchSize = VALUE_NOT_SET; |
| 120 | |
| 121 | private int maxRows = VALUE_NOT_SET; |
| 122 | |
| 123 | private int queryTimeout = VALUE_NOT_SET; |
| 124 | |
| 125 | private boolean ignoreWarnings = true; |
| 126 | |
| 127 | private boolean verifyCursorPosition = true; |
| 128 | |
| 129 | private SQLExceptionTranslator exceptionTranslator; |
| 130 | |
| 131 | private boolean initialized = false; |
| 132 | |
| 133 | private boolean driverSupportsAbsolute = false; |
| 134 | |
| 135 | private boolean useSharedExtendedConnection = false; |
| 136 | |
| 137 | |
| 138 | public AbstractCursorItemReader() { |
| 139 | super(); |
| 140 | } |
| 141 | |
| 142 | /** |
| 143 | * Assert that mandatory properties are set. |
| 144 | * |
| 145 | * @throws IllegalArgumentException if either data source or sql properties |
| 146 | * not set. |
| 147 | */ |
| 148 | public void afterPropertiesSet() throws Exception { |
| 149 | Assert.notNull(dataSource, "DataSource must be provided"); |
| 150 | } |
| 151 | |
| 152 | /** |
| 153 | * Public setter for the data source for injection purposes. |
| 154 | * |
| 155 | * @param dataSource |
| 156 | */ |
| 157 | public void setDataSource(DataSource dataSource) { |
| 158 | this.dataSource = dataSource; |
| 159 | } |
| 160 | |
| 161 | /** |
| 162 | * Public getter for the data source. |
| 163 | * |
| 164 | * @return the dataSource |
| 165 | */ |
| 166 | public DataSource getDataSource() { |
| 167 | return this.dataSource; |
| 168 | } |
| 169 | |
| 170 | /** |
| 171 | * Prepare the given JDBC Statement (or PreparedStatement or |
| 172 | * CallableStatement), applying statement settings such as fetch size, max |
| 173 | * rows, and query timeout. @param stmt the JDBC Statement to prepare |
| 174 | * @throws SQLException |
| 175 | * |
| 176 | * @see #setFetchSize |
| 177 | * @see #setMaxRows |
| 178 | * @see #setQueryTimeout |
| 179 | */ |
| 180 | protected void applyStatementSettings(PreparedStatement stmt) throws SQLException { |
| 181 | if (fetchSize != VALUE_NOT_SET) { |
| 182 | stmt.setFetchSize(fetchSize); |
| 183 | stmt.setFetchDirection(ResultSet.FETCH_FORWARD); |
| 184 | } |
| 185 | if (maxRows != VALUE_NOT_SET) { |
| 186 | stmt.setMaxRows(maxRows); |
| 187 | } |
| 188 | if (queryTimeout != VALUE_NOT_SET) { |
| 189 | stmt.setQueryTimeout(queryTimeout); |
| 190 | } |
| 191 | } |
| 192 | |
| 193 | /** |
| 194 | * Return the exception translator for this instance. |
| 195 | * |
| 196 | * Creates a default SQLErrorCodeSQLExceptionTranslator for the specified |
| 197 | * DataSource if none is set. |
| 198 | */ |
| 199 | protected SQLExceptionTranslator getExceptionTranslator() { |
| 200 | synchronized(this) { |
| 201 | if (exceptionTranslator == null) { |
| 202 | if (dataSource != null) { |
| 203 | exceptionTranslator = new SQLErrorCodeSQLExceptionTranslator(dataSource); |
| 204 | } |
| 205 | else { |
| 206 | exceptionTranslator = new SQLStateSQLExceptionTranslator(); |
| 207 | } |
| 208 | } |
| 209 | } |
| 210 | return exceptionTranslator; |
| 211 | } |
| 212 | |
| 213 | /** |
| 214 | * Throw a SQLWarningException if we're not ignoring warnings, else log the |
| 215 | * warnings (at debug level). |
| 216 | * |
| 217 | * @param statement the current statement to obtain the warnings from, if there are any. |
| 218 | * @throws SQLException |
| 219 | * |
| 220 | * @see org.springframework.jdbc.SQLWarningException |
| 221 | */ |
| 222 | protected void handleWarnings(Statement statement) throws SQLWarningException, |
| 223 | SQLException { |
| 224 | if (ignoreWarnings) { |
| 225 | if (log.isDebugEnabled()) { |
| 226 | SQLWarning warningToLog = statement.getWarnings(); |
| 227 | while (warningToLog != null) { |
| 228 | log.debug("SQLWarning ignored: SQL state '" + warningToLog.getSQLState() + "', error code '" |
| 229 | + warningToLog.getErrorCode() + "', message [" + warningToLog.getMessage() + "]"); |
| 230 | warningToLog = warningToLog.getNextWarning(); |
| 231 | } |
| 232 | } |
| 233 | } |
| 234 | else { |
| 235 | SQLWarning warnings = statement.getWarnings(); |
| 236 | if (warnings != null) { |
| 237 | throw new SQLWarningException("Warning not ignored", warnings); |
| 238 | } |
| 239 | } |
| 240 | } |
| 241 | |
| 242 | /** |
| 243 | * Moves the cursor in the ResultSet to the position specified by the row |
| 244 | * parameter by traversing the ResultSet. |
| 245 | * @param row |
| 246 | */ |
| 247 | private void moveCursorToRow(int row) { |
| 248 | try { |
| 249 | int count = 0; |
| 250 | while (row != count && rs.next()) { |
| 251 | count++; |
| 252 | } |
| 253 | } |
| 254 | catch (SQLException se) { |
| 255 | throw getExceptionTranslator().translate("Attempted to move ResultSet to last committed row", getSql(), se); |
| 256 | } |
| 257 | } |
| 258 | |
| 259 | /** |
| 260 | * Gives the JDBC driver a hint as to the number of rows that should be |
| 261 | * fetched from the database when more rows are needed for this |
| 262 | * <code>ResultSet</code> object. If the fetch size specified is zero, the |
| 263 | * JDBC driver ignores the value. |
| 264 | * |
| 265 | * @param fetchSize the number of rows to fetch |
| 266 | * @see ResultSet#setFetchSize(int) |
| 267 | */ |
| 268 | public void setFetchSize(int fetchSize) { |
| 269 | this.fetchSize = fetchSize; |
| 270 | } |
| 271 | |
| 272 | /** |
| 273 | * Sets the limit for the maximum number of rows that any |
| 274 | * <code>ResultSet</code> object can contain to the given number. |
| 275 | * |
| 276 | * @param maxRows the new max rows limit; zero means there is no limit |
| 277 | * @see Statement#setMaxRows(int) |
| 278 | */ |
| 279 | public void setMaxRows(int maxRows) { |
| 280 | this.maxRows = maxRows; |
| 281 | } |
| 282 | |
| 283 | /** |
| 284 | * Sets the number of seconds the driver will wait for a |
| 285 | * <code>Statement</code> object to execute to the given number of seconds. |
| 286 | * If the limit is exceeded, an <code>SQLException</code> is thrown. |
| 287 | * |
| 288 | * @param queryTimeout seconds the new query timeout limit in seconds; zero |
| 289 | * means there is no limit |
| 290 | * @see Statement#setQueryTimeout(int) |
| 291 | */ |
| 292 | public void setQueryTimeout(int queryTimeout) { |
| 293 | this.queryTimeout = queryTimeout; |
| 294 | } |
| 295 | |
| 296 | /** |
| 297 | * Set whether SQLWarnings should be ignored (only logged) or exception |
| 298 | * should be thrown. |
| 299 | * |
| 300 | * @param ignoreWarnings if TRUE, warnings are ignored |
| 301 | */ |
| 302 | public void setIgnoreWarnings(boolean ignoreWarnings) { |
| 303 | this.ignoreWarnings = ignoreWarnings; |
| 304 | } |
| 305 | |
| 306 | /** |
| 307 | * Allow verification of cursor position after current row is processed by |
| 308 | * RowMapper or RowCallbackHandler. Default value is TRUE. |
| 309 | * |
| 310 | * @param verifyCursorPosition if true, cursor position is verified |
| 311 | */ |
| 312 | public void setVerifyCursorPosition(boolean verifyCursorPosition) { |
| 313 | this.verifyCursorPosition = verifyCursorPosition; |
| 314 | } |
| 315 | |
| 316 | /** |
| 317 | * Indicate whether the JDBC driver supports setting the absolute row on a |
| 318 | * {@link ResultSet}. It is recommended that this is set to |
| 319 | * <code>true</code> for JDBC drivers that supports ResultSet.absolute() as |
| 320 | * it may improve performance, especially if a step fails while working with |
| 321 | * a large data set. |
| 322 | * |
| 323 | * @see ResultSet#absolute(int) |
| 324 | * |
| 325 | * @param driverSupportsAbsolute <code>false</code> by default |
| 326 | */ |
| 327 | public void setDriverSupportsAbsolute(boolean driverSupportsAbsolute) { |
| 328 | this.driverSupportsAbsolute = driverSupportsAbsolute; |
| 329 | } |
| 330 | |
| 331 | /** |
| 332 | * Indicate whether the connection used for the cursor should be used by all other processing |
| 333 | * thus sharing the same transaction. If this is set to false, which is the default, then the |
| 334 | * cursor will be opened using in its connection and will not participate in any transactions |
| 335 | * started for the rest of the step processing. If you set this flag to true then you must |
| 336 | * wrap the DataSource in a {@link ExtendedConnectionDataSourceProxy} to prevent the |
| 337 | * connection from being closed and released after each commit. |
| 338 | * |
| 339 | * When you set this option to <code>true</code> then the statement used to open the cursor |
| 340 | * will be created with both 'READ_ONLY' and 'HOLD_CUSORS_OVER_COMMIT' options. This allows |
| 341 | * holding the cursor open over transaction start and commits performed in the step processing. |
| 342 | * To use this feature you need a database that supports this and a JDBC driver supporting |
| 343 | * JDBC 3.0 or later. |
| 344 | * |
| 345 | * @param useSharedExtendedConnection <code>false</code> by default |
| 346 | */ |
| 347 | public void setUseSharedExtendedConnection(boolean useSharedExtendedConnection) { |
| 348 | this.useSharedExtendedConnection = useSharedExtendedConnection; |
| 349 | } |
| 350 | |
| 351 | public boolean isUseSharedExtendedConnection() { |
| 352 | return useSharedExtendedConnection; |
| 353 | } |
| 354 | |
| 355 | public abstract String getSql(); |
| 356 | |
| 357 | /** |
| 358 | * Check the result set is in synch with the currentRow attribute. This is |
| 359 | * important to ensure that the user hasn't modified the current row. |
| 360 | */ |
| 361 | private void verifyCursorPosition(long expectedCurrentRow) throws SQLException { |
| 362 | if (verifyCursorPosition) { |
| 363 | if (expectedCurrentRow != this.rs.getRow()) { |
| 364 | throw new InvalidDataAccessResourceUsageException("Unexpected cursor position change."); |
| 365 | } |
| 366 | } |
| 367 | } |
| 368 | |
| 369 | /** |
| 370 | * Close the cursor and database connection. Make call to cleanupOnClose so sub classes can cleanup |
| 371 | * any resources they have allocated. |
| 372 | */ |
| 373 | protected void doClose() throws Exception { |
| 374 | initialized = false; |
| 375 | JdbcUtils.closeResultSet(this.rs); |
| 376 | rs = null; |
| 377 | cleanupOnClose(); |
| 378 | if (useSharedExtendedConnection && dataSource instanceof ExtendedConnectionDataSourceProxy) { |
| 379 | ((ExtendedConnectionDataSourceProxy)dataSource).stopCloseSuppression(this.con); |
| 380 | if (!TransactionSynchronizationManager.isActualTransactionActive()) { |
| 381 | DataSourceUtils.releaseConnection(con, dataSource); |
| 382 | } |
| 383 | } |
| 384 | else { |
| 385 | JdbcUtils.closeConnection(this.con); |
| 386 | } |
| 387 | } |
| 388 | |
| 389 | protected abstract void cleanupOnClose() throws Exception; |
| 390 | |
| 391 | /** |
| 392 | * Execute the statement to open the cursor. |
| 393 | */ |
| 394 | @Override |
| 395 | protected final void doOpen() throws Exception { |
| 396 | |
| 397 | Assert.state(!initialized, "Stream is already initialized. Close before re-opening."); |
| 398 | Assert.isNull(rs, "ResultSet still open! Close before re-opening."); |
| 399 | |
| 400 | initializeConnection(); |
| 401 | openCursor(con); |
| 402 | initialized = true; |
| 403 | |
| 404 | } |
| 405 | |
| 406 | protected void initializeConnection() { |
| 407 | Assert.state(getDataSource() != null, "DataSource must not be null."); |
| 408 | |
| 409 | try { |
| 410 | if (useSharedExtendedConnection) { |
| 411 | if (!(getDataSource() instanceof ExtendedConnectionDataSourceProxy)) { |
| 412 | throw new InvalidDataAccessApiUsageException( |
| 413 | "You must use a ExtendedConnectionDataSourceProxy for the dataSource when " + |
| 414 | "useSharedExtendedConnection is set to true."); |
| 415 | } |
| 416 | this.con = DataSourceUtils.getConnection(dataSource); |
| 417 | ((ExtendedConnectionDataSourceProxy)dataSource).startCloseSuppression(this.con); |
| 418 | } |
| 419 | else { |
| 420 | this.con = dataSource.getConnection(); |
| 421 | } |
| 422 | } |
| 423 | catch (SQLException se) { |
| 424 | close(); |
| 425 | throw getExceptionTranslator().translate("Executing query", getSql(), se); |
| 426 | } |
| 427 | } |
| 428 | |
| 429 | protected abstract void openCursor(Connection con); |
| 430 | |
| 431 | /** |
| 432 | * Read next row and map it to item, verify cursor position if |
| 433 | * {@link #setVerifyCursorPosition(boolean)} is true. |
| 434 | */ |
| 435 | protected T doRead() throws Exception { |
| 436 | if (rs == null) { |
| 437 | throw new ReaderNotOpenException("Reader must be open before it can be read."); |
| 438 | } |
| 439 | |
| 440 | try { |
| 441 | if (!rs.next()) { |
| 442 | return null; |
| 443 | } |
| 444 | int currentRow = getCurrentItemCount(); |
| 445 | T item = readCursor(rs, currentRow); |
| 446 | verifyCursorPosition(currentRow); |
| 447 | return item; |
| 448 | } |
| 449 | catch (SQLException se) { |
| 450 | throw getExceptionTranslator().translate("Attempt to process next row failed", getSql(), se); |
| 451 | } |
| 452 | } |
| 453 | |
| 454 | /** |
| 455 | * Read the cursor and map to the type of object this reader should return. This method must be |
| 456 | * overriden by subclasses. |
| 457 | * |
| 458 | * @param rs The current result set |
| 459 | * @param currentRow Current position of the result set |
| 460 | * @return the mapped object at the cursor position |
| 461 | * @throws SQLException |
| 462 | */ |
| 463 | protected abstract T readCursor(ResultSet rs, int currentRow) throws SQLException; |
| 464 | |
| 465 | /** |
| 466 | * Use {@link ResultSet#absolute(int)} if possible, otherwise scroll by |
| 467 | * calling {@link ResultSet#next()}. |
| 468 | */ |
| 469 | protected void jumpToItem(int itemIndex) throws Exception { |
| 470 | if (driverSupportsAbsolute) { |
| 471 | try { |
| 472 | rs.absolute(itemIndex); |
| 473 | } |
| 474 | catch (SQLException e) { |
| 475 | // Driver does not support rs.absolute(int) revert to |
| 476 | // traversing ResultSet |
| 477 | log.warn("The JDBC driver does not appear to support ResultSet.absolute(). Consider" |
| 478 | + " reverting to the default behavior setting the driverSupportsAbsolute to false", e); |
| 479 | |
| 480 | moveCursorToRow(itemIndex); |
| 481 | } |
| 482 | } |
| 483 | else { |
| 484 | moveCursorToRow(itemIndex); |
| 485 | } |
| 486 | } |
| 487 | |
| 488 | } |