1 package org.apache.velocity.runtime.resource.loader;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import java.io.BufferedInputStream;
23 import java.io.InputStream;
24 import java.sql.Connection;
25 import java.sql.PreparedStatement;
26 import java.sql.ResultSet;
27 import java.sql.SQLException;
28 import java.sql.Timestamp;
29
30 import javax.naming.InitialContext;
31 import javax.naming.NamingException;
32 import javax.sql.DataSource;
33
34 import org.apache.commons.collections.ExtendedProperties;
35 import org.apache.velocity.exception.ResourceNotFoundException;
36 import org.apache.velocity.runtime.resource.Resource;
37 import org.apache.velocity.util.ExceptionUtils;
38 import org.apache.velocity.util.StringUtils;
39
40 /**
41 * <P>This is a simple template file loader that loads templates
42 * from a DataSource instead of plain files.
43 *
44 * <P>It can be configured with a datasource name, a table name,
45 * id column (name), content column (the template body) and a
46 * datetime column (for last modification info).
47 * <br>
48 * <br>
49 * Example configuration snippet for velocity.properties:
50 * <br>
51 * <br>
52 * resource.loader = file, ds <br>
53 * <br>
54 * ds.resource.loader.public.name = DataSource <br>
55 * ds.resource.loader.description = Velocity DataSource Resource Loader <br>
56 * ds.resource.loader.class = org.apache.velocity.runtime.resource.loader.DataSourceResourceLoader <br>
57 * ds.resource.loader.resource.datasource = java:comp/env/jdbc/Velocity <br>
58 * ds.resource.loader.resource.table = tb_velocity_template <br>
59 * ds.resource.loader.resource.keycolumn = id_template <br>
60 * ds.resource.loader.resource.templatecolumn = template_definition <br>
61 * ds.resource.loader.resource.timestampcolumn = template_timestamp <br>
62 * ds.resource.loader.cache = false <br>
63 * ds.resource.loader.modificationCheckInterval = 60 <br>
64 * <br>
65 * <P>Optionally, the developer can instantiate the DataSourceResourceLoader and set the DataSource via code in
66 * a manner similar to the following:
67 * <BR>
68 * <BR>
69 * DataSourceResourceLoader ds = new DataSourceResourceLoader();<BR>
70 * ds.setDataSource(DATASOURCE);<BR>
71 * Velocity.setProperty("ds.resource.loader.instance",ds);<BR>
72 * <P> The property <code>ds.resource.loader.class</code> should be left out, otherwise all the other
73 * properties in velocity.properties would remain the same.
74 * <BR>
75 * <BR>
76 *
77 * Example WEB-INF/web.xml: <br>
78 * <br>
79 * <resource-ref> <br>
80 * <description>Velocity template DataSource</description> <br>
81 * <res-ref-name>jdbc/Velocity</res-ref-name> <br>
82 * <res-type>javax.sql.DataSource</res-type> <br>
83 * <res-auth>Container</res-auth> <br>
84 * </resource-ref> <br>
85 * <br>
86 * <br>
87 * and Tomcat 4 server.xml file: <br>
88 * [...] <br>
89 * <Context path="/exampleVelocity" docBase="exampleVelocity" debug="0"> <br>
90 * [...] <br>
91 * <ResourceParams name="jdbc/Velocity"> <br>
92 * <parameter> <br>
93 * <name>driverClassName</name> <br>
94 * <value>org.hsql.jdbcDriver</value> <br>
95 * </parameter> <br>
96 * <parameter> <br>
97 * <name>driverName</name> <br>
98 * <value>jdbc:HypersonicSQL:database</value> <br>
99 * </parameter> <br>
100 * <parameter> <br>
101 * <name>user</name> <br>
102 * <value>database_username</value> <br>
103 * </parameter> <br>
104 * <parameter> <br>
105 * <name>password</name> <br>
106 * <value>database_password</value> <br>
107 * </parameter> <br>
108 * </ResourceParams> <br>
109 * [...] <br>
110 * </Context> <br>
111 * [...] <br>
112 * <br>
113 * Example sql script:<br>
114 * CREATE TABLE tb_velocity_template ( <br>
115 * id_template varchar (40) NOT NULL , <br>
116 * template_definition text (16) NOT NULL , <br>
117 * template_timestamp datetime NOT NULL <br>
118 * ) <br>
119 *
120 * @author <a href="mailto:wglass@forio.com">Will Glass-Husain</a>
121 * @author <a href="mailto:matt@raibledesigns.com">Matt Raible</a>
122 * @author <a href="mailto:david.kinnvall@alertir.com">David Kinnvall</a>
123 * @author <a href="mailto:paulo.gaspar@krankikom.de">Paulo Gaspar</a>
124 * @author <a href="mailto:lachiewicz@plusnet.pl">Sylwester Lachiewicz</a>
125 * @author <a href="mailto:henning@apache.org">Henning P. Schmiedehausen</a>
126 * @version $Id: DataSourceResourceLoader.java 471259 2006-11-04 20:26:57Z henning $
127 */
128 public class DataSourceResourceLoader extends ResourceLoader
129 {
130 private String dataSourceName;
131 private String tableName;
132 private String keyColumn;
133 private String templateColumn;
134 private String timestampColumn;
135 private InitialContext ctx;
136 private DataSource dataSource;
137
138 /**
139 * @see org.apache.velocity.runtime.resource.loader.ResourceLoader#init(org.apache.commons.collections.ExtendedProperties)
140 */
141 public void init(ExtendedProperties configuration)
142 {
143 dataSourceName = StringUtils.nullTrim(configuration.getString("resource.datasource"));
144 tableName = StringUtils.nullTrim(configuration.getString("resource.table"));
145 keyColumn = StringUtils.nullTrim(configuration.getString("resource.keycolumn"));
146 templateColumn = StringUtils.nullTrim(configuration.getString("resource.templatecolumn"));
147 timestampColumn = StringUtils.nullTrim(configuration.getString("resource.timestampcolumn"));
148
149 if (dataSource != null)
150 {
151 if (log.isDebugEnabled())
152 {
153 log.debug("DataSourceResourceLoader: using dataSource instance with table \""
154 + tableName + "\"");
155 log.debug("DataSourceResourceLoader: using columns \""
156 + keyColumn + "\", \"" + templateColumn + "\" and \""
157 + timestampColumn + "\"");
158 }
159
160 log.trace("DataSourceResourceLoader initialized.");
161 }
162 else if (dataSourceName != null)
163 {
164 if (log.isDebugEnabled())
165 {
166 log.debug("DataSourceResourceLoader: using \"" + dataSourceName
167 + "\" datasource with table \"" + tableName + "\"");
168 log.debug("DataSourceResourceLoader: using columns \""
169 + keyColumn + "\", \"" + templateColumn + "\" and \""
170 + timestampColumn + "\"");
171 }
172
173 log.trace("DataSourceResourceLoader initialized.");
174 }
175 else
176 {
177 log.warn("DataSourceResourceLoader not properly initialized. No DataSource was identified.");
178 }
179 }
180
181 /**
182 * Set the DataSource used by this resource loader. Call this as an alternative to
183 * specifying the data source name via properties.
184 * @param dataSource The data source for this ResourceLoader.
185 */
186 public void setDataSource(final DataSource dataSource)
187 {
188 this.dataSource = dataSource;
189 }
190
191 /**
192 * @see org.apache.velocity.runtime.resource.loader.ResourceLoader#isSourceModified(org.apache.velocity.runtime.resource.Resource)
193 */
194 public boolean isSourceModified(final Resource resource)
195 {
196 return (resource.getLastModified() !=
197 readLastModified(resource, "checking timestamp"));
198 }
199
200 /**
201 * @see org.apache.velocity.runtime.resource.loader.ResourceLoader#getLastModified(org.apache.velocity.runtime.resource.Resource)
202 */
203 public long getLastModified(final Resource resource)
204 {
205 return readLastModified(resource, "getting timestamp");
206 }
207
208 /**
209 * Get an InputStream so that the Runtime can build a
210 * template with it.
211 *
212 * @param name name of template
213 * @return InputStream containing template
214 * @throws ResourceNotFoundException
215 */
216 public synchronized InputStream getResourceStream(final String name)
217 throws ResourceNotFoundException
218 {
219 if (org.apache.commons.lang.StringUtils.isEmpty(name))
220 {
221 throw new ResourceNotFoundException ("DataSourceResourceLoader: "
222 + "Template name was empty or null");
223 }
224
225 Connection conn = null;
226 ResultSet rs = null;
227 try
228 {
229 conn = openDbConnection();
230 rs = readData(conn, templateColumn, name);
231
232 if (rs.next())
233 {
234 InputStream ascStream = rs.getAsciiStream(templateColumn);
235 if (ascStream == null)
236 {
237 throw new ResourceNotFoundException("DataSourceResourceLoader: "
238 + "template column for '" + name + "' is null");
239 }
240
241 return new BufferedInputStream(ascStream);
242 }
243 else
244 {
245 throw new ResourceNotFoundException("DataSourceResourceLoader: "
246 + "could not find resource '" + name + "'");
247
248 }
249 }
250 catch(SQLException sqle)
251 {
252 String msg = "DataSourceResourceLoader: database problem while getting resource '"
253 + name + "': ";
254
255 log.error(msg, sqle);
256 throw new ResourceNotFoundException(msg);
257 }
258 catch(NamingException ne)
259 {
260 String msg = "DataSourceResourceLoader: database problem while getting resource '"
261 + name + "': ";
262
263 log.error(msg, ne);
264 throw new ResourceNotFoundException(msg);
265 }
266 finally
267 {
268 closeResultSet(rs);
269 closeDbConnection(conn);
270 }
271 }
272
273 /**
274 * Fetches the last modification time of the resource
275 *
276 * @param resource Resource object we are finding timestamp of
277 * @param operation string for logging, indicating caller's intention
278 *
279 * @return timestamp as long
280 */
281 private long readLastModified(final Resource resource, final String operation)
282 {
283 long timeStamp = 0;
284
285 /*
286 * get the template name from the resource
287 */
288 String name = resource.getName();
289
290 if (name == null || name.length() == 0)
291 {
292 log.error("DataSourceResourceLoader: "
293 + "Template name was empty or null");
294 }
295 else
296 {
297 Connection conn = null;
298 ResultSet rs = null;
299
300 try
301 {
302 conn = openDbConnection();
303 rs = readData(conn, timestampColumn, name);
304
305 if (rs.next())
306 {
307 Timestamp ts = rs.getTimestamp(timestampColumn);
308 timeStamp = ts != null ? ts.getTime() : 0;
309 }
310 else
311 {
312 log.error("DataSourceResourceLoader: could not find resource "
313 + name + " while " + operation);
314 }
315 }
316 catch(SQLException sqle)
317 {
318 String msg = "DataSourceResourceLoader: database problem while " + operation + " of '"
319 + name + "': ";
320
321 log.error(msg, sqle);
322 throw ExceptionUtils.createRuntimeException(msg, sqle);
323 }
324 catch(NamingException ne)
325 {
326 String msg = "DataSourceResourceLoader: database problem while " + operation + " of '"
327 + name + "': ";
328
329 log.error(msg, ne);
330 throw ExceptionUtils.createRuntimeException(msg, ne);
331 }
332 finally
333 {
334 closeResultSet(rs);
335 closeDbConnection(conn);
336 }
337 }
338 return timeStamp;
339 }
340
341 /**
342 * Gets connection to the datasource specified through the configuration
343 * parameters.
344 *
345 * @return connection
346 */
347 private Connection openDbConnection()
348 throws NamingException, SQLException
349 {
350 if (dataSource != null)
351 {
352 return dataSource.getConnection();
353 }
354
355 if (ctx == null)
356 {
357 ctx = new InitialContext();
358 }
359
360 dataSource = (DataSource) ctx.lookup(dataSourceName);
361
362 return dataSource.getConnection();
363 }
364
365 /**
366 * Closes connection to the datasource
367 */
368 private void closeDbConnection(final Connection conn)
369 {
370 if (conn != null)
371 {
372 try
373 {
374 conn.close();
375 }
376 catch (RuntimeException re)
377 {
378 throw re;
379 }
380 catch (Exception e)
381 {
382 log.warn("DataSourceResourceLoader: problem when closing connection", e);
383 }
384 }
385 }
386
387 /**
388 * Closes the result set.
389 */
390 private void closeResultSet(final ResultSet rs)
391 {
392 if (rs != null)
393 {
394 try
395 {
396 rs.close();
397 }
398 catch (RuntimeException re)
399 {
400 throw re;
401 }
402 catch (Exception e)
403 {
404 log.warn("DataSourceResourceLoader: problem when closing result set: ", e);
405 }
406 }
407 }
408
409 /**
410 * Reads the data from the datasource. It simply does the following query :
411 * <br>
412 * SELECT <i>columnNames</i> FROM <i>tableName</i> WHERE <i>keyColumn</i>
413 * = '<i>templateName</i>'
414 * <br>
415 * where <i>keyColumn</i> is a class member set in init()
416 *
417 * @param conn connection to datasource
418 * @param columnNames columns to fetch from datasource
419 * @param templateName name of template to fetch
420 * @return result set from query
421 */
422 private ResultSet readData(final Connection conn, final String columnNames, final String templateName)
423 throws SQLException
424 {
425 PreparedStatement ps = conn.prepareStatement("SELECT " + columnNames + " FROM "+ tableName + " WHERE " + keyColumn + " = ?");
426 ps.setString(1, templateName);
427 return ps.executeQuery();
428 }
429 }
430