geirm 01/02/23 02:06:55 Added: whiteboard/geir DataSourceResourceLoader.java Log: I think this is Paulo's riff, and renamed to DataSourceResourceLoader. Putting here to let David, Paulo et all take a look, and if ok, we can replace DBResourceLoader with it. Revision Changes Path 1.1 jakarta-velocity/whiteboard/geir/DataSourceResourceLoader.java Index: DataSourceResourceLoader.java =================================================================== package org.apache.velocity.runtime.resource.loader; /* * The Apache Software License, Version 1.1 * * Copyright (c) 2001 The Apache Software Foundation. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. The end-user documentation included with the redistribution, if * any, must include the following acknowlegement: * "This product includes software developed by the * Apache Software Foundation (http://www.apache.org/)." * Alternately, this acknowlegement may appear in the software itself, * if and wherever such third-party acknowlegements normally appear. * * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software * Foundation" must not be used to endorse or promote products derived * from this software without prior written permission. For written * permission, please contact [EMAIL PROTECTED] * * 5. Products derived from this software may not be called "Apache" * nor may "Apache" appear in their names without prior written * permission of the Apache Group. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. */ import java.io.InputStream; import java.io.BufferedInputStream; import java.util.Map; import java.util.Hashtable; import java.sql.*; import javax.sql.DataSource; import javax.naming.InitialContext; import org.apache.velocity.runtime.Runtime; import org.apache.velocity.runtime.resource.Resource; /** * This is a simple template file loader that loads templates * from a DataSource instead of plain files. * * It can be configured with a datasource name, a table name, * id column (name), content column (the template body) and a * timestamp column (for last modification info). * * Example configuration snippet for velociy.properties: * * resource.loader.1.public.name = DB * resource.loader.1.description = Velocity DB Resource Loader * resource.loader.1.class = org.apache.velocity.runtime.resource.loader.DBResourceLoader * resource.loader.1.resource.datasource = jdbc/SomeDS * resource.loader.1.resource.table = template_table * resource.loader.1.resource.keycolumn = template_id * resource.loader.1.resource.templatecolumn = template_definition * resource.loader.1.resource.timestampcolumn = template_timestamp * resource.loader.1.cache = false * resource.loader.1.modificationCheckInterval = 60 * * @author <a href="mailto:[EMAIL PROTECTED]">David Kinnvall</a> */ public class DataSourceResourceLoader extends ResourceLoader { private String dataSourceName; private String tableName; private String keyColumn; private String templateColumn; private String timestampColumn; private InitialContext ctx; private DataSource dataSource; /* * This should probably be moved into the super class, * the stand init stuff. For the properties that all * loaders will probably share. */ public void init(Map initializer) { dataSourceName = (String) initializer.get("resource.datasource"); tableName = (String) initializer.get("resource.table"); keyColumn = (String) initializer.get("resource.keycolumn"); templateColumn = (String) initializer.get("resource.templatecolumn"); timestampColumn = (String) initializer.get("resource.timestampcolumn"); Runtime.info("Resources Loaded From: " + dataSourceName + "/" + tableName); Runtime.info( "Resource Loader using columns: " + keyColumn + ", " + templateColumn + " and " + timestampColumn); Runtime.info("Resource Loader Initalized."); } public boolean isSourceModified(Resource resource) { return (resource.getLastModified() != readLastModified(resource, "checking timestamp")); } public long getLastModified(Resource resource) { return readLastModified(resource, "getting timestamp"); } /** * Get an InputStream so that the Runtime can build a * template with it. */ public synchronized InputStream getResourceStream( String name ) throws Exception { if (name == null || name.length() == 0) { throw new Exception ("Need to specify a template name!"); } try { Connection conn = openDbConnection(); try { ResultSet rs = readData(conn, templateColumn, name); try { if (rs.next()) { return new BufferedInputStream(rs.getAsciiStream(templateColumn)); } else { Runtime.error( "DBResourceLoader Error: cannot find resource " + name); } } finally { rs.close(); } } finally { closeDbConnection(conn); } } catch(Exception e) { Runtime.error( "DBResourceLoader Error: database problem trying to load resource " + name + ": " + e.toString() ); } return null; } private long readLastModified(Resource resource, String i_operation) { String name = resource.getName(); try { Connection conn = openDbConnection(); try { ResultSet rs = readData(conn, timestampColumn, name); try { if (rs.next()) { return rs.getLong(timestampColumn); } else { Runtime.error("DBResourceLoader Error: while " + i_operation + " could not find resource " + name); } } finally { rs.close(); } } finally { closeDbConnection(conn); } } catch(Exception e) { Runtime.error( "DBResourceLoader Error: error while " + i_operation + " when trying to load resource " + name + ": " + e.toString() ); } return 0; } private Connection openDbConnection() throws Exception { if(ctx == null) { ctx = new InitialContext(); } if(dataSource == null) { dataSource = (DataSource)ctx.lookup(dataSourceName); } return dataSource.getConnection(); } private void closeDbConnection(Connection conn) { try { conn.close(); } catch (Exception e) { Runtime.info( "DBResourceLoader Quirk: problem when closing connection: " + e.toString()); } } private ResultSet readData(Connection conn, String columnNames, String templateName) throws SQLException { Statement stmt = conn.createStatement(); String sql = "select " + columnNames + " from " + tableName + " where " + keyColumn + " = '" + templateName + "'"; return stmt.executeQuery(sql); } }
