001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.dbutils.wrappers;
018
019 import java.io.InputStream;
020 import java.io.Reader;
021 import java.lang.reflect.InvocationHandler;
022 import java.lang.reflect.Method;
023 import java.math.BigDecimal;
024 import java.net.URL;
025 import java.sql.Blob;
026 import java.sql.Clob;
027 import java.sql.Date;
028 import java.sql.Ref;
029 import java.sql.ResultSet;
030 import java.sql.Time;
031 import java.sql.Timestamp;
032 import java.util.HashMap;
033 import java.util.Map;
034
035 import org.apache.commons.dbutils.ProxyFactory;
036
037 /**
038 * Decorates a <code>ResultSet</code> with checks for a SQL NULL value on each
039 * <code>getXXX</code> method. If a column value obtained by a
040 * <code>getXXX</code> method is not SQL NULL, the column value is returned. If
041 * the column value is SQL null, an alternate value is returned. The alternate
042 * value defaults to the Java <code>null</code> value, which can be overridden
043 * for instances of the class.
044 *
045 * <p>
046 * Usage example:
047 * <blockquote>
048 * <pre>
049 * Connection conn = // somehow get a connection
050 * Statement stmt = conn.createStatement();
051 * ResultSet rs = stmt.executeQuery("SELECT col1, col2 FROM table1");
052 *
053 * // Wrap the result set for SQL NULL checking
054 * SqlNullCheckedResultSet wrapper = new SqlNullCheckedResultSet(rs);
055 * wrapper.setNullString("---N/A---"); // Set null string
056 * wrapper.setNullInt(-999); // Set null integer
057 * rs = ProxyFactory.instance().createResultSet(wrapper);
058 *
059 * while (rs.next()) {
060 * // If col1 is SQL NULL, value returned will be "---N/A---"
061 * String col1 = rs.getString("col1");
062 * // If col2 is SQL NULL, value returned will be -999
063 * int col2 = rs.getInt("col2");
064 * }
065 * rs.close();
066 * </pre>
067 * </blockquote>
068 * </p>
069 * <p>Unlike some other classes in DbUtils, this class is NOT thread-safe.</p>
070 */
071 public class SqlNullCheckedResultSet implements InvocationHandler {
072
073 /**
074 * Maps normal method names (ie. "getBigDecimal") to the corresponding null
075 * Method object (ie. getNullBigDecimal).
076 */
077 private static final Map nullMethods = new HashMap();
078
079 static {
080 Method[] methods = SqlNullCheckedResultSet.class.getMethods();
081 for (int i = 0; i < methods.length; i++) {
082 String methodName = methods[i].getName();
083
084 if (methodName.startsWith("getNull")) {
085 String normalName = "get" + methodName.substring(7);
086 nullMethods.put(normalName, methods[i]);
087 }
088 }
089 }
090
091 /**
092 * The factory to create proxies with.
093 */
094 private static final ProxyFactory factory = ProxyFactory.instance();
095
096 /**
097 * Wraps the <code>ResultSet</code> in an instance of this class. This is
098 * equivalent to:
099 * <pre>
100 * ProxyFactory.instance().createResultSet(new SqlNullCheckedResultSet(rs));
101 * </pre>
102 *
103 * @param rs The <code>ResultSet</code> to wrap.
104 * @return wrapped ResultSet
105 */
106 public static ResultSet wrap(ResultSet rs) {
107 return factory.createResultSet(new SqlNullCheckedResultSet(rs));
108 }
109
110 private InputStream nullAsciiStream = null;
111 private BigDecimal nullBigDecimal = null;
112 private InputStream nullBinaryStream = null;
113 private Blob nullBlob = null;
114 private boolean nullBoolean = false;
115 private byte nullByte = 0;
116 private byte[] nullBytes = null;
117 private Reader nullCharacterStream = null;
118 private Clob nullClob = null;
119 private Date nullDate = null;
120 private double nullDouble = 0.0;
121 private float nullFloat = 0.0f;
122 private int nullInt = 0;
123 private long nullLong = 0;
124 private Object nullObject = null;
125 private Ref nullRef = null;
126 private short nullShort = 0;
127 private String nullString = null;
128 private Time nullTime = null;
129 private Timestamp nullTimestamp = null;
130 private URL nullURL = null;
131
132 /**
133 * The wrapped result.
134 */
135 private final ResultSet rs;
136
137 /**
138 * Constructs a new instance of
139 * <code>SqlNullCheckedResultSet</code>
140 * to wrap the specified <code>ResultSet</code>.
141 * @param rs ResultSet to wrap
142 */
143 public SqlNullCheckedResultSet(ResultSet rs) {
144 super();
145 this.rs = rs;
146 }
147
148 /**
149 * Returns the value when a SQL null is encountered as the result of
150 * invoking a <code>getAsciiStream</code> method.
151 *
152 * @return the value
153 */
154 public InputStream getNullAsciiStream() {
155 return this.nullAsciiStream;
156 }
157
158 /**
159 * Returns the value when a SQL null is encountered as the result of
160 * invoking a <code>getBigDecimal</code> method.
161 *
162 * @return the value
163 */
164 public BigDecimal getNullBigDecimal() {
165 return this.nullBigDecimal;
166 }
167
168 /**
169 * Returns the value when a SQL null is encountered as the result of
170 * invoking a <code>getBinaryStream</code> method.
171 *
172 * @return the value
173 */
174 public InputStream getNullBinaryStream() {
175 return this.nullBinaryStream;
176 }
177
178 /**
179 * Returns the value when a SQL null is encountered as the result of
180 * invoking a <code>getBlob</code> method.
181 *
182 * @return the value
183 */
184 public Blob getNullBlob() {
185 return this.nullBlob;
186 }
187
188 /**
189 * Returns the value when a SQL null is encountered as the result of
190 * invoking a <code>getBoolean</code> method.
191 *
192 * @return the value
193 */
194 public boolean getNullBoolean() {
195 return this.nullBoolean;
196 }
197
198 /**
199 * Returns the value when a SQL null is encountered as the result of
200 * invoking a <code>getByte</code> method.
201 *
202 * @return the value
203 */
204 public byte getNullByte() {
205 return this.nullByte;
206 }
207
208 /**
209 * Returns the value when a SQL null is encountered as the result of
210 * invoking a <code>getBytes</code> method.
211 *
212 * @return the value
213 */
214 public byte[] getNullBytes() {
215 return this.nullBytes;
216 }
217
218 /**
219 * Returns the value when a SQL null is encountered as the result of
220 * invoking a <code>getCharacterStream</code> method.
221 *
222 * @return the value
223 */
224 public Reader getNullCharacterStream() {
225 return this.nullCharacterStream;
226 }
227
228 /**
229 * Returns the value when a SQL null is encountered as the result of
230 * invoking a <code>getClob</code> method.
231 *
232 * @return the value
233 */
234 public Clob getNullClob() {
235 return this.nullClob;
236 }
237
238 /**
239 * Returns the value when a SQL null is encountered as the result of
240 * invoking a <code>getDate</code> method.
241 *
242 * @return the value
243 */
244 public Date getNullDate() {
245 return this.nullDate;
246 }
247
248 /**
249 * Returns the value when a SQL null is encountered as the result of
250 * invoking a <code>getDouble</code> method.
251 *
252 * @return the value
253 */
254 public double getNullDouble() {
255 return this.nullDouble;
256 }
257
258 /**
259 * Returns the value when a SQL null is encountered as the result of
260 * invoking a <code>getFloat</code> method.
261 *
262 * @return the value
263 */
264 public float getNullFloat() {
265 return this.nullFloat;
266 }
267
268 /**
269 * Returns the value when a SQL null is encountered as the result of
270 * invoking a <code>getInt</code> method.
271 *
272 * @return the value
273 */
274 public int getNullInt() {
275 return this.nullInt;
276 }
277
278 /**
279 * Returns the value when a SQL null is encountered as the result of
280 * invoking a <code>getLong</code> method.
281 *
282 * @return the value
283 */
284 public long getNullLong() {
285 return this.nullLong;
286 }
287
288 /**
289 * Returns the value when a SQL null is encountered as the result of
290 * invoking a <code>getObject</code> method.
291 *
292 * @return the value
293 */
294 public Object getNullObject() {
295 return this.nullObject;
296 }
297
298 /**
299 * Returns the value when a SQL null is encountered as the result of
300 * invoking a <code>getRef</code> method.
301 *
302 * @return the value
303 */
304 public Ref getNullRef() {
305 return this.nullRef;
306 }
307
308 /**
309 * Returns the value when a SQL null is encountered as the result of
310 * invoking a <code>getShort</code> method.
311 *
312 * @return the value
313 */
314 public short getNullShort() {
315 return this.nullShort;
316 }
317
318 /**
319 * Returns the value when a SQL null is encountered as the result of
320 * invoking a <code>getString</code> method.
321 *
322 * @return the value
323 */
324 public String getNullString() {
325 return this.nullString;
326 }
327
328 /**
329 * Returns the value when a SQL null is encountered as the result of
330 * invoking a <code>getTime</code> method.
331 *
332 * @return the value
333 */
334 public Time getNullTime() {
335 return this.nullTime;
336 }
337
338 /**
339 * Returns the value when a SQL null is encountered as the result of
340 * invoking a <code>getTimestamp</code> method.
341 *
342 * @return the value
343 */
344 public Timestamp getNullTimestamp() {
345 return this.nullTimestamp;
346 }
347
348 /**
349 * Returns the value when a SQL null is encountered as the result of
350 * invoking a <code>getURL</code> method.
351 *
352 * @return the value
353 */
354 public URL getNullURL() {
355 return this.nullURL;
356 }
357
358 /**
359 * Intercepts calls to <code>get*</code> methods and calls the appropriate
360 * <code>getNull*</code> method if the <code>ResultSet</code> returned
361 * <code>null</code>.
362 *
363 * @throws Throwable
364 * @see java.lang.reflect.InvocationHandler#invoke(java.lang.Object, java.lang.reflect.Method, java.lang.Object[])
365 */
366 public Object invoke(Object proxy, Method method, Object[] args)
367 throws Throwable {
368
369 Object result = method.invoke(this.rs, args);
370
371 Method nullMethod = (Method) nullMethods.get(method.getName());
372
373 // Check nullMethod != null first so that we don't call wasNull()
374 // before a true getter method was invoked on the ResultSet.
375 return (nullMethod != null && this.rs.wasNull())
376 ? nullMethod.invoke(this, (Object[]) null)
377 : result;
378 }
379
380 /**
381 * Sets the value to return when a SQL null is encountered as the result of
382 * invoking a <code>getAsciiStream</code> method.
383 *
384 * @param nullAsciiStream the value
385 */
386 public void setNullAsciiStream(InputStream nullAsciiStream) {
387 this.nullAsciiStream = nullAsciiStream;
388 }
389
390 /**
391 * Sets the value to return when a SQL null is encountered as the result of
392 * invoking a <code>getBigDecimal</code> method.
393 *
394 * @param nullBigDecimal the value
395 */
396 public void setNullBigDecimal(BigDecimal nullBigDecimal) {
397 this.nullBigDecimal = nullBigDecimal;
398 }
399
400 /**
401 * Sets the value to return when a SQL null is encountered as the result of
402 * invoking a <code>getBinaryStream</code> method.
403 *
404 * @param nullBinaryStream the value
405 */
406 public void setNullBinaryStream(InputStream nullBinaryStream) {
407 this.nullBinaryStream = nullBinaryStream;
408 }
409
410 /**
411 * Sets the value to return when a SQL null is encountered as the result of
412 * invoking a <code>getBlob</code> method.
413 *
414 * @param nullBlob the value
415 */
416 public void setNullBlob(Blob nullBlob) {
417 this.nullBlob = nullBlob;
418 }
419
420 /**
421 * Sets the value to return when a SQL null is encountered as the result of
422 * invoking a <code>getBoolean</code> method.
423 *
424 * @param nullBoolean the value
425 */
426 public void setNullBoolean(boolean nullBoolean) {
427 this.nullBoolean = nullBoolean;
428 }
429
430 /**
431 * Sets the value to return when a SQL null is encountered as the result of
432 * invoking a <code>getByte</code> method.
433 *
434 * @param nullByte the value
435 */
436 public void setNullByte(byte nullByte) {
437 this.nullByte = nullByte;
438 }
439
440 /**
441 * Sets the value to return when a SQL null is encountered as the result of
442 * invoking a <code>getBytes</code> method.
443 *
444 * @param nullBytes the value
445 */
446 public void setNullBytes(byte[] nullBytes) {
447 this.nullBytes = nullBytes;
448 }
449
450 /**
451 * Sets the value to return when a SQL null is encountered as the result of
452 * invoking a <code>getCharacterStream</code> method.
453 *
454 * @param nullCharacterStream the value
455 */
456 public void setNullCharacterStream(Reader nullCharacterStream) {
457 this.nullCharacterStream = nullCharacterStream;
458 }
459
460 /**
461 * Sets the value to return when a SQL null is encountered as the result of
462 * invoking a <code>getClob</code> method.
463 *
464 * @param nullClob the value
465 */
466 public void setNullClob(Clob nullClob) {
467 this.nullClob = nullClob;
468 }
469
470 /**
471 * Sets the value to return when a SQL null is encountered as the result of
472 * invoking a <code>getDate</code> method.
473 *
474 * @param nullDate the value
475 */
476 public void setNullDate(Date nullDate) {
477 this.nullDate = nullDate;
478 }
479
480 /**
481 * Sets the value to return when a SQL null is encountered as the result of
482 * invoking a <code>getDouble</code> method.
483 *
484 * @param nullDouble the value
485 */
486 public void setNullDouble(double nullDouble) {
487 this.nullDouble = nullDouble;
488 }
489
490 /**
491 * Sets the value to return when a SQL null is encountered as the result of
492 * invoking a <code>getFloat</code> method.
493 *
494 * @param nullFloat the value
495 */
496 public void setNullFloat(float nullFloat) {
497 this.nullFloat = nullFloat;
498 }
499
500 /**
501 * Sets the value to return when a SQL null is encountered as the result of
502 * invoking a <code>getInt</code> method.
503 *
504 * @param nullInt the value
505 */
506 public void setNullInt(int nullInt) {
507 this.nullInt = nullInt;
508 }
509
510 /**
511 * Sets the value to return when a SQL null is encountered as the result of
512 * invoking a <code>getLong</code> method.
513 *
514 * @param nullLong the value
515 */
516 public void setNullLong(long nullLong) {
517 this.nullLong = nullLong;
518 }
519
520 /**
521 * Sets the value to return when a SQL null is encountered as the result of
522 * invoking a <code>getObject</code> method.
523 *
524 * @param nullObject the value
525 */
526 public void setNullObject(Object nullObject) {
527 this.nullObject = nullObject;
528 }
529
530 /**
531 * Sets the value to return when a SQL null is encountered as the result of
532 * invoking a <code>getRef</code> method.
533 *
534 * @param nullRef the value
535 */
536 public void setNullRef(Ref nullRef) {
537 this.nullRef = nullRef;
538 }
539
540 /**
541 * Sets the value to return when a SQL null is encountered as the result of
542 * invoking a <code>getShort</code> method.
543 *
544 * @param nullShort the value
545 */
546 public void setNullShort(short nullShort) {
547 this.nullShort = nullShort;
548 }
549
550 /**
551 * Sets the value to return when a SQL null is encountered as the result of
552 * invoking a <code>getString</code> method.
553 *
554 * @param nullString the value
555 */
556 public void setNullString(String nullString) {
557 this.nullString = nullString;
558 }
559
560 /**
561 * Sets the value to return when a SQL null is encountered as the result of
562 * invoking a <code>getTime</code> method.
563 *
564 * @param nullTime the value
565 */
566 public void setNullTime(Time nullTime) {
567 this.nullTime = nullTime;
568 }
569
570 /**
571 * Sets the value to return when a SQL null is encountered as the result of
572 * invoking a <code>getTimestamp</code> method.
573 *
574 * @param nullTimestamp the value
575 */
576 public void setNullTimestamp(Timestamp nullTimestamp) {
577 this.nullTimestamp = nullTimestamp;
578 }
579
580 /**
581 * Sets the value to return when a SQL null is encountered as the result of
582 * invoking a <code>getURL</code> method.
583 *
584 * @param nullURL the value
585 */
586 public void setNullURL(URL nullURL) {
587 this.nullURL = nullURL;
588 }
589
590 }