|
1 package org.apache.velocity.runtime.resource.loader;
2
3
18
19 import java.io.InputStream  ;
20 import java.io.BufferedInputStream ;
21 import java.util.Hashtable ;
22
23 import javax.sql.DataSource ;
24 import javax.naming.InitialContext ;
25
26 import org.apache.velocity.runtime.Runtime;
27 import org.apache.velocity.runtime.resource.Resource;
28
29 import org.apache.velocity.exception.ResourceNotFoundException;
30
31 import org.apache.commons.collections.ExtendedProperties;
32 import java.sql.Connection ;
33 import java.sql.ResultSet ;
34 import java.sql.Statement ;
35 import java.sql.SQLException ;
36
37
110 public class DataSourceResourceLoader extends ResourceLoader
111 {
112 private String dataSourceName;
113 private String tableName;
114 private String keyColumn;
115 private String templateColumn;
116 private String timestampColumn;
117 private InitialContext ctx;
118 private DataSource dataSource;
119
120 public void init( ExtendedProperties configuration)
121 {
122 dataSourceName = configuration.getString("resource.datasource");
123 tableName = configuration.getString("resource.table");
124 keyColumn = configuration.getString("resource.keycolumn");
125 templateColumn = configuration.getString("resource.templatecolumn");
126 timestampColumn = configuration.getString("resource.timestampcolumn");
127
128 Runtime.info("Resources Loaded From: " + dataSourceName + "/" + tableName);
129 Runtime.info( "Resource Loader using columns: " + keyColumn + ", "
130 + templateColumn + " and " + timestampColumn);
131 Runtime.info("Resource Loader Initalized.");
132 }
133
134 public boolean isSourceModified(Resource resource)
135 {
136 return (resource.getLastModified() !=
137 readLastModified(resource, "checking timestamp"));
138 }
139
140 public long getLastModified(Resource resource)
141 {
142 return readLastModified(resource, "getting timestamp");
143 }
144
145
152 public synchronized InputStream getResourceStream( String name )
153 throws ResourceNotFoundException
154 {
155 if (name == null || name.length() == 0)
156 {
157 throw new ResourceNotFoundException ("Need to specify a template name!");
158 }
159
160 try
161 {
162 Connection conn = openDbConnection();
163
164 try
165 {
166 ResultSet rs = readData(conn, templateColumn, name);
167
168 try
169 {
170 if (rs.next())
171 {
172 return new
173 BufferedInputStream (rs.getAsciiStream(templateColumn));
174 }
175 else
176 {
177 String msg = "DataSourceResourceLoader Error: cannot find resource "
178 + name;
179 Runtime.error(msg );
180
181 throw new ResourceNotFoundException (msg);
182 }
183 }
184 finally
185 {
186 rs.close();
187 }
188 }
189 finally
190 {
191 closeDbConnection(conn);
192 }
193 }
194 catch(Exception e)
195 {
196 String msg = "DataSourceResourceLoader Error: database problem trying to load resource "
197 + name + ": " + e.toString();
198
199 Runtime.error( msg );
200
201 throw new ResourceNotFoundException (msg);
202
203 }
204
205 }
206
207
215 private long readLastModified(Resource resource, String i_operation)
216 {
217
220
221 String name = resource.getName();
222 try
223 {
224 Connection conn = openDbConnection();
225
226 try
227 {
228 ResultSet rs = readData(conn, timestampColumn, name);
229 try
230 {
231 if (rs.next())
232 {
233 return rs.getTimestamp(timestampColumn).getTime();
234 }
235 else
236 {
237 Runtime.error("DataSourceResourceLoader Error: while "
238 + i_operation
239 + " could not find resource " + name);
240 }
241 }
242 finally
243 {
244 rs.close();
245 }
246 }
247 finally
248 {
249 closeDbConnection(conn);
250 }
251 }
252 catch(Exception e)
253 {
254 Runtime.error( "DataSourceResourceLoader Error: error while "
255 + i_operation + " when trying to load resource "
256 + name + ": " + e.toString() );
257 }
258 return 0;
259 }
260
261
267 private Connection openDbConnection()
268 throws Exception
269 {
270 if(ctx == null)
271 {
272 ctx = new InitialContext ();
273 }
274
275 if(dataSource == null)
276 {
277 dataSource = (DataSource )ctx.lookup(dataSourceName);
278 }
279
280 return dataSource.getConnection();
281 }
282
283
286 private void closeDbConnection(Connection conn)
287 {
288 try
289 {
290 conn.close();
291 }
292 catch (Exception e)
293 {
294 Runtime.info(
295 "DataSourceResourceLoader Quirk: problem when closing connection: "
296 + e.toString());
297 }
298 }
299
300
313 private ResultSet readData(Connection conn, String columnNames, String templateName)
314 throws SQLException
315 {
316 Statement stmt = conn.createStatement();
317
318 String sql = "SELECT " + columnNames
319 + " FROM " + tableName
320 + " WHERE " + keyColumn + " = '" + templateName + "'";
321
322 return stmt.executeQuery(sql);
323 }
324 }
325 |
Popular Tags |
Java API By Example, From Geeks To Geeks.