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106
107 package com.Yasna.forum.database;
108
109 import java.sql.*;
110
111 import com.Yasna.forum.*;
112 import com.Yasna.util.*;
113
114
120 public class DbTreeWalker implements TreeWalker {
121
122
123 private static final String  GET_CHILD =
124 "SELECT yazdMessageTree.childID, yazdMessage.creationDate FROM " +
125 "yazdMessageTree, yazdMessage WHERE " +
126 "yazdMessageTree.childID=yazdMessage.messageID AND " +
127 "yazdMessageTree.parentID=? ORDER BY yazdMessage.creationDate";
128 private static final String CHILD_COUNT =
129 "SELECT count(*) FROM yazdMessageTree WHERE parentID=?";
130 private static final String INDEX_OF_CHILD =
131 "SELECT yazdMessageTree.childID, yazdMessage.creationDate " +
132 "FROM yazdMessageTree, yazdMessage WHERE yazdMessageTree.childID=yazdMessage.messageID " +
133 "AND yazdMessageTree.parentID=? ORDER BY yazdMessage.creationDate";
134
135 private DbForumThread thread;
136 private DbForumFactory factory;
137
138 public DbTreeWalker(DbForumThread thread, DbForumFactory factory) {
139 this.thread = thread;
140 this.factory = factory;
141 }
142
143
148 public ForumMessage getRoot() {
149 return thread.getRootMessage();
150 }
151
152
161 public ForumMessage getChild(ForumMessage parent, int index) {
162 ForumMessage message = null;
163 Connection con = null;
164 PreparedStatement pstmt = null;
165 try {
166 con = DbConnectionManager.getConnection();
167 pstmt = con.prepareStatement(GET_CHILD);
168 pstmt.setInt(1, parent.getID());
169 ResultSet rs = pstmt.executeQuery();
170 while (rs.next() && index > 0) {
171 index--;
172 }
173 if (index == 0) {
174 int messageID = rs.getInt(1);
175 message = thread.getMessage(messageID);
176 }
177 }
178 catch (Exception e) {
179 System.err.println("Error in DbMessageTreeWalker:getChild("
180 + index + ")-" + e);
181 e.printStackTrace();
182 }
183 finally {
184 try { pstmt.close(); }
185 catch (Exception e) { e.printStackTrace(); }
186 try { con.close(); }
187 catch (Exception e) { e.printStackTrace(); }
188 }
189 return message;
190 }
191
192
199 public int getChildCount(ForumMessage parent) {
200 int childCount = 0;
201 Connection con = null;
202 PreparedStatement pstmt = null;
203 try {
204 con = DbConnectionManager.getConnection();
205 pstmt = con.prepareStatement(CHILD_COUNT);
206 pstmt.setInt(1, parent.getID());
207 ResultSet rs = pstmt.executeQuery();
208 rs.next();
209 childCount = rs.getInt(1);
210 }
211 catch (Exception e) {
212 System.err.println("Error in DbTreeWalker:getChildCount()-"
213 + e);
214 e.printStackTrace();
215 }
216 finally {
217 try { pstmt.close(); }
218 catch (Exception e) { e.printStackTrace(); }
219 try { con.close(); }
220 catch (Exception e) { e.printStackTrace(); }
221 }
222 return childCount;
223 }
224
225
230 public int getRecursiveChildCount(ForumMessage parent) {
231 int numChildren = 0;
232 int num = getChildCount(parent);
233 numChildren += num;
234 for (int i=0; i<num; i++) {
235 ForumMessage child = getChild(parent,i);
236 if (child != null) {
237 numChildren += getRecursiveChildCount(child);
238 }
239 }
240 return numChildren;
241 }
242
243
246 public int getIndexOfChild(ForumMessage parent, ForumMessage child) {
247 int index = 0;
248 Connection con = null;
249 PreparedStatement pstmt = null;
250 ResultSet rs = null;
251 try {
252 con = DbConnectionManager.getConnection();
253 pstmt = con.prepareStatement(INDEX_OF_CHILD);
254 pstmt.setInt(1, parent.getID());
255 rs = pstmt.executeQuery();
256 while (rs.next()) {
257 if (rs.getInt(1) == child.getID()) {
258 break;
259 }
260 index++;
261 }
262 }
263 catch (Exception e) {
264 System.err.println("Error in DbTreeWalker:getIndexOfChild()-" + e);
265 }
266 finally {
267 try { pstmt.close(); }
268 catch (Exception e) { e.printStackTrace(); }
269 try { con.close(); }
270 catch (Exception e) { e.printStackTrace(); }
271 }
272 return index;
273 }
274
275
282 public boolean isLeaf(ForumMessage node) {
283 return (getChildCount(node) == 0);
284 }
285 }
286 |
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