01: /*
02: * ============================================================================
03: * GNU Lesser General Public License
04: * ============================================================================
05: *
06: * JasperReports - Free Java report-generating library.
07: * Copyright (C) 2001-2006 JasperSoft Corporation http://www.jaspersoft.com
08: *
09: * This library is free software; you can redistribute it and/or
10: * modify it under the terms of the GNU Lesser General Public
11: * License as published by the Free Software Foundation; either
12: * version 2.1 of the License, or (at your option) any later version.
13: *
14: * This library is distributed in the hope that it will be useful,
15: * but WITHOUT ANY WARRANTY; without even the implied warranty of
16: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17: * Lesser General Public License for more details.
18: *
19: * You should have received a copy of the GNU Lesser General Public
20: * License along with this library; if not, write to the Free Software
21: * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
22: *
23: * JasperSoft Corporation
24: * 303 Second Street, Suite 450 North
25: * San Francisco, CA 94107
26: * http://www.jaspersoft.com
27: */
28: package net.sf.jasperreports.engine.query;
29:
30: import net.sf.jasperreports.engine.JRDataSource;
31: import net.sf.jasperreports.engine.JRException;
32:
33: /**
34: * Query executer interface.
35: * <p/>
36: * An implementation of this interface is created when the input data of a report/dataset
37: * is specified by a query.
38: * <p/>
39: * The implementation will run the query and create a {@link net.sf.jasperreports.engine.JRDataSource JRDataSource}
40: * from the result.
41: * <p/>
42: * The query executers would usually be initialized by a {@link net.sf.jasperreports.engine.query.JRQueryExecuterFactory JRQueryExecuterFactory}
43: * with the query and the parameter values.
44: *
45: * @author Lucian Chirita (lucianc@users.sourceforge.net)
46: * @version $Id: JRQueryExecuter.java 1229 2006-04-19 10:27:35Z teodord $
47: * @see net.sf.jasperreports.engine.query.JRQueryExecuterFactory
48: */
49: public interface JRQueryExecuter {
50: /**
51: * Executes the query and creates a {@link JRDataSource JRDataSource} out of the result.
52: *
53: * @return a {@link JRDataSource JRDataSource} wrapping the query execution result.
54: * @throws JRException
55: */
56: public JRDataSource createDatasource() throws JRException;
57:
58: /**
59: * Closes resources kept open during the data source iteration.
60: * <p/>
61: * This method is called after the report is filled or the dataset is iterated.
62: * If a resource is not needed after the data source has been created, it should be
63: * released at the end of {@link #createDatasource() createDatasource}.
64: */
65: public void close();
66:
67: /**
68: * Cancels the query if it's currently running.
69: * <p/>
70: * This method will be called from a different thread if the client decides to
71: * cancel the filling process.
72: *
73: * @return <code>true</code> iff the query was running and it has been cancelled
74: * @throws JRException
75: */
76: public boolean cancelQuery() throws JRException;
77: }
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