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Posted to dev@velocity.apache.org by ge...@apache.org on 2001/02/23 11:06:55 UTC
cvs commit: jakarta-velocity/whiteboard/geir DataSourceResourceLoader.java
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 apache@apache.org.
*
* 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:david.kinnvall@alertir.com">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);
}
}