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106
107 package com.Yasna.forum.database;
108
109 import java.util.Iterator  ;
110 import java.sql.*;
111
112 import com.Yasna.forum.*;
113
114
117 public class DbThreadIterator implements Iterator {
118
119
120 private static final String MESSAGE_COUNT =
121 "SELECT count(messageID) FROM yazdMessage WHERE threadID=?";
122 private static final String GET_MESSAGES =
123 "SELECT messageID, creationDate FROM yazdMessage WHERE threadID=? " +
124 "ORDER BY creationDate ASC";
125
126 private ForumThread thread;
127 private int [] messages;
128 private int currentIndex = -1;
129
130 private ForumMessage nextMessage = null;
131
132 protected DbThreadIterator(ForumThread thread) {
133 this.thread = thread;
134 Connection con = null;
135 PreparedStatement pstmt = null;
136 try {
137 con = DbConnectionManager.getConnection();
138 pstmt = con.prepareStatement(MESSAGE_COUNT);
139 pstmt.setInt(1, thread.getID());
140 ResultSet rs = pstmt.executeQuery();
141 rs.next();
142 messages = new int[rs.getInt(1)];
143 pstmt.close();
144
145 pstmt = con.prepareStatement(GET_MESSAGES);
146 pstmt.setInt(1, thread.getID());
147 rs = pstmt.executeQuery();
148 for (int i=0; i<messages.length; i++) {
149 rs.next();
150 messages[i] = rs.getInt(1);
151 }
152 }
153 catch( SQLException sqle ) {
154 System.err.println("Error in DbThreadIterator:constructor()-" + sqle);
155 }
156 finally {
157 try { pstmt.close(); }
158 catch (Exception e) { e.printStackTrace(); }
159 try { con.close(); }
160 catch (Exception e) { e.printStackTrace(); }
161 }
162 }
163
164 protected DbThreadIterator(ForumThread thread, int startIndex, int numResults)
165 {
166 this.thread = thread;
167
168 int[] tempMessages = new int[numResults];
169 int messageCount = 0;
173
174 Connection con = null;
175 PreparedStatement pstmt = null;
176
177 try {
178 con = DbConnectionManager.getConnection();
179 pstmt = con.prepareStatement(GET_MESSAGES);
180 pstmt.setInt(1, thread.getID());
181 ResultSet rs = pstmt.executeQuery();
182 for (int i=0; i<startIndex; i++) {
184 rs.next();
185 }
186 for (int i=0; i<numResults; i++) {
188 if (rs.next()) {
189 tempMessages[messageCount] = rs.getInt("messageID");
190 messageCount++;
191 }
192 else {
193 break;
194 }
195 }
196 }
197 catch( SQLException sqle ) {
198 System.err.println("Error in DbThreadIterator:constructor()-" + sqle);
199 }
200 finally {
201 try { pstmt.close(); }
202 catch (Exception e) { e.printStackTrace(); }
203 try { con.close(); }
204 catch (Exception e) { e.printStackTrace(); }
205 }
206 messages = new int[messageCount];
207 for (int i=0; i<messageCount; i++) {
208 messages[i] = tempMessages[i];
209 }
210 }
211
212
217 public boolean hasNext() {
218 if (currentIndex+1 >= messages.length) {
221 return false;
222 }
223 return true;
224
225
243 }
244
245
251 public Object next() throws java.util.NoSuchElementException {
252 ForumMessage message = null;
253 if (nextMessage != null) {
254 message = nextMessage;
255 nextMessage = null;
256 }
257 else {
258 message = getNextMessage();
259 if (message == null) {
260 throw new java.util.NoSuchElementException ();
261 }
262 }
263 return message;
264 }
265
266
272 public void remove() throws UnsupportedOperationException {
273 throw new UnsupportedOperationException ();
274 }
275
276
280 private ForumMessage getNextMessage() {
281 while (currentIndex+1 < messages.length) {
282 currentIndex++;
283 try {
284 ForumMessage message = thread.getMessage(messages[currentIndex]);
285 return message;
286 }
287 catch (ForumMessageNotFoundException mnfe) { }
288 }
289 return null;
290 }
291 }
292 |
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