ResultSetIterator


1   /*
2    * $Header: /cvsroot/valuelist/valuelist/src/java/net/mlw/vlh/adapter/jdbc/dynabean/fix/ResultSetIterator.java,v 1.1 2004/06/03 14:27:13 mlavwilson Exp $
3    * $Revision: 1.1 $
4    * $Date: 2004/06/03 14:27:13 $
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61  
62  
63  package net.mlw.vlh.adapter.jdbc.dynabean.fix;
64  
65  
66  import java.sql.SQLException  ;
67  import java.util.Iterator  ;
68  import java.util.NoSuchElementException  ;
69  
70  import org.apache.commons.beanutils.DynaBean;
71  import org.apache.commons.beanutils.DynaClass;
72  
73  
74  /**
75   * <p>Implementation of <code>java.util.Iterator</code> returned by the
76   * <code>iterator()</code> method of {@link ResultSetDynaClass}.  Each
77   * object returned by this iterator will be a {@link DynaBean} that
78   * represents a single row from the result set being wrapped.</p>
79   *
80   * @author Craig R. McClanahan
81   * @version $Revision: 1.1 $ $Date: 2004/06/03 14:27:13 $
82   */
83  
84  public class ResultSetIterator implements DynaBean, Iterator   {
85  
86  
87      // ------------------------------------------------------------ Constructor
88  
89  
90      /**
91       * <p>Construct an <code>Iterator</code> for the result set being wrapped
92       * by the specified {@link ResultSetDynaClass}.</p>
93       *
94       * @param dynaClass The {@link ResultSetDynaClass} wrapping the
95       *  result set we will iterate over
96       */
97      ResultSetIterator(ResultSetDynaClass dynaClass) {
98  
99          this.dynaClass = dynaClass;
100 
101     }
102 
103 
104     // ----------------------------------------------------- Instance Variables
105 
106 
107 
108     /**
109      * <p>Flag indicating whether the result set is currently positioned at a
110      * row for which we have not yet returned an element in the iteration.</p>
111      */
112     protected boolean current = false;
113 
114 
115     /**
116      * <p>The {@link ResultSetDynaClass} we are associated with.</p>
117      */
118     protected ResultSetDynaClass dynaClass = null;
119 
120 
121     /**
122      * <p>Flag indicating whether the result set has indicated that there are
123      * no further rows.</p>
124      */
125     protected boolean eof = false;
126 
127 
128     // ------------------------------------------------------- DynaBean Methods
129 
130 
131     /**
132      * Does the specified mapped property contain a value for the specified
133      * key value?
134      *
135      * @param name Name of the property to check
136      * @param key Name of the key to check
137      *
138      * @exception IllegalArgumentException if there is no property
139      *  of the specified name
140      */
141     public boolean contains(String   name, String   key) {
142 
143         throw new UnsupportedOperationException  
144             ("FIXME - mapped properties not currently supported");
145 
146     }
147 
148 
149     /**
150      * Return the value of a simple property with the specified name.
151      *
152      * @param name Name of the property whose value is to be retrieved
153      *
154      * @exception IllegalArgumentException if there is no property
155      *  of the specified name
156      */
157     public Object   get(String   name) {
158 
159         if (dynaClass.getDynaProperty(name) == null) {
160             throw new IllegalArgumentException  (name);
161         }
162         try {
163             return (dynaClass.getResultSet().getObject(name));
164         } catch (SQLException   e) {
165             return null;
166         }
167 
168     }
169 
170 
171     /**
172      * Return the value of an indexed property with the specified name.
173      *
174      * @param name Name of the property whose value is to be retrieved
175      * @param index Index of the value to be retrieved
176      *
177      * @exception IllegalArgumentException if there is no property
178      *  of the specified name
179      * @exception IllegalArgumentException if the specified property
180      *  exists, but is not indexed
181      * @exception IndexOutOfBoundsException if the specified index
182      *  is outside the range of the underlying property
183      * @exception NullPointerException if no array or List has been
184      *  initialized for this property
185      */
186     public Object   get(String   name, int index) {
187 
188         throw new UnsupportedOperationException  
189             ("FIXME - indexed properties not currently supported");
190 
191     }
192 
193 
194     /**
195      * Return the value of a mapped property with the specified name,
196      * or <code>null</code> if there is no value for the specified key.
197      *
198      * @param name Name of the property whose value is to be retrieved
199      * @param key Key of the value to be retrieved
200      *
201      * @exception IllegalArgumentException if there is no property
202      *  of the specified name
203      * @exception IllegalArgumentException if the specified property
204      *  exists, but is not mapped
205      */
206     public Object   get(String   name, String   key) {
207 
208         throw new UnsupportedOperationException  
209             ("FIXME - mapped properties not currently supported");
210 
211     }
212 
213 
214     /**
215      * Return the <code>DynaClass</code> instance that describes the set of
216      * properties available for this DynaBean.
217      */
218     public DynaClass getDynaClass() {
219 
220         return (this.dynaClass);
221 
222     }
223 
224 
225     /**
226      * Remove any existing value for the specified key on the
227      * specified mapped property.
228      *
229      * @param name Name of the property for which a value is to
230      *  be removed
231      * @param key Key of the value to be removed
232      *
233      * @exception IllegalArgumentException if there is no property
234      *  of the specified name
235      */
236     public void remove(String   name, String   key) {
237 
238         throw new UnsupportedOperationException  
239             ("FIXME - mapped operations not currently supported");
240 
241     }
242 
243 
244     /**
245      * Set the value of a simple property with the specified name.
246      *
247      * @param name Name of the property whose value is to be set
248      * @param value Value to which this property is to be set
249      *
250      * @exception ConversionException if the specified value cannot be
251      *  converted to the type required for this property
252      * @exception IllegalArgumentException if there is no property
253      *  of the specified name
254      * @exception NullPointerException if an attempt is made to set a
255      *  primitive property to null
256      */
257     public void set(String   name, Object   value) {
258 
259         if (dynaClass.getDynaProperty(name) == null) {
260             throw new IllegalArgumentException  (name);
261         }
262         try {
263             dynaClass.getResultSet().updateObject(name, value);
264         } catch (SQLException   e) {
265             throw new RuntimeException  
266                 ("set(" + name + "): SQLException: " + e);
267         }
268 
269     }
270 
271 
272     /**
273      * Set the value of an indexed property with the specified name.
274      *
275      * @param name Name of the property whose value is to be set
276      * @param index Index of the property to be set
277      * @param value Value to which this property is to be set
278      *
279      * @exception ConversionException if the specified value cannot be
280      *  converted to the type required for this property
281      * @exception IllegalArgumentException if there is no property
282      *  of the specified name
283      * @exception IllegalArgumentException if the specified property
284      *  exists, but is not indexed
285      * @exception IndexOutOfBoundsException if the specified index
286      *  is outside the range of the underlying property
287      */
288     public void set(String   name, int index, Object   value) {
289 
290         throw new UnsupportedOperationException  
291             ("FIXME - indexed properties not currently supported");
292 
293     }
294 
295 
296     /**
297      * Set the value of a mapped property with the specified name.
298      *
299      * @param name Name of the property whose value is to be set
300      * @param key Key of the property to be set
301      * @param value Value to which this property is to be set
302      *
303      * @exception ConversionException if the specified value cannot be
304      *  converted to the type required for this property
305      * @exception IllegalArgumentException if there is no property
306      *  of the specified name
307      * @exception IllegalArgumentException if the specified property
308      *  exists, but is not mapped
309      */
310     public void set(String   name, String   key, Object   value) {
311 
312         throw new UnsupportedOperationException  
313             ("FIXME - mapped properties not currently supported");
314 
315     }
316 
317 
318     // ------------------------------------------------------- Iterator Methods
319 
320 
321     /**
322      * <p>Return <code>true</code> if the iteration has more elements.</p>
323      */
324     public boolean hasNext() {
325 
326         try {
327             advance();
328             return (!eof);
329         } catch (SQLException   e) {
330             throw new RuntimeException  ("hasNext():  SQLException:  " + e);
331         }
332 
333     }
334 
335 
336     /**
337      * <p>Return the next element in the iteration.</p>
338      */
339     public Object   next() {
340 
341         try {
342             advance();
343             if (eof) {
344                 throw new NoSuchElementException  ();
345             }
346             current = false;
347             return (this);
348         } catch (SQLException   e) {
349             throw new RuntimeException  ("next():  SQLException:  " + e);
350         }
351 
352     }
353 
354 
355     /**
356      * <p>Remove the current element from the iteration.  This method is
357      * not supported.</p>
358      */
359     public void remove() {
360 
361         throw new UnsupportedOperationException  ("remove()");
362 
363     }
364 
365 
366     // ------------------------------------------------------ Protected Methods
367 
368 
369     /**
370      * <p>Advance the result set to the next row, if there is not a current
371      * row (and if we are not already at eof).</p>
372      *
373      * @exception SQLException if the result set throws an exception
374      */
375     protected void advance() throws SQLException   {
376 
377         if (!current && !eof) {
378             if (dynaClass.getResultSet().next()) {
379                 current = true;
380                 eof = false;
381             } else {
382                 current = false;
383                 eof = true;
384             }
385         }
386 
387     }
388 
389 
390 }
391
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