package org.apache.commons.digester3.examples.api.dbinsert;
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import java.sql.Connection;
import java.util.Iterator;
import org.apache.commons.digester3.Rule;
import org.apache.commons.digester3.examples.api.dbinsert.Row.Column;
/**
* See Main.java.
*/
public class RowInserterRule
extends Rule
{
private Connection conn;
public RowInserterRule( Connection conn )
{
this.conn = conn;
}
/**
* This method is invoked when the start tag for an xml element representing
* a database row is encountered. It pushes a new Row instance onto the
* digester stack (rather like an ObjectCreateRule) so that column data
* can be stored on it.
*/
@Override
public void begin( String namespace, String name, org.xml.sax.Attributes attrs )
{
getDigester().push( new Row() );
}
/**
* This method is invoked when the end tag for an xml element representing
* a database row is encountered. It pops a fully-configured Row instance
* off the digester stack, accesses the object below it on the stack (a
* Table object) to get the tablename, then does an SQL insert). Actually,
* here we just print out text rather than do the sql insert, but the
* real implementation should be fairly simple.
* <p>
* Note that after this rule completes, the row/column information is
* <i>discarded</i>, ie this rule performs actions <i>as the input is
* parsed</i>. This contrasts with the more usual way digester is used,
* which is to build trees of objects for later use. But it's a perfectly
* valid use of Digester.
*/
@Override
public void end( String namespace, String name )
{
Row row = getDigester().pop();
Table table = getDigester().peek();
// Obviously, all this would be replaced by code like:
// stmt = conn.prepareStatement();
// stmt.setString(n, value);
//
// Many improvements can then be implemented, such as using the
// PreparedStatement.getParameterMetaData method to retrieve
// retrieve parameter types, etc.
StringBuilder colnames = new StringBuilder();
StringBuilder colvalues = new StringBuilder();
for ( Iterator<Column> i = row.getColumns().iterator(); i.hasNext(); )
{
Column column = i.next();
if ( colnames.length() > 0 )
{
colnames.append( ", " );
colvalues.append( ", " );
}
colnames.append( "'" );
colnames.append( column.getName() );
colnames.append( "'" );
colvalues.append( "'" );
colvalues.append( column.getValue() );
colvalues.append( "'" );
}
StringBuilder buf = new StringBuilder();
buf.append( "insert into " );
buf.append( table.getName() );
buf.append( " (" );
buf.append( colnames.toString() );
buf.append( ") values (" );
buf.append( colvalues.toString() );
buf.append( ")" );
// here the prepared statement would be executed....
System.out.println( buf.toString() );
}
}