Hi David,
At a first glance:
- DBResourceLoader.isSourceModified() has too much code in common
with DBResourceLoader.getLastModified();
- There is some more code repeated.
Without (almost) changing the functionality, what about this
implementation (just the DBResourceLoader class)?
Paulo
The code follows:
public class DBResourceLoader 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);
}
}
