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Java > Open Source Codes > net > sf > jasperreports > engine > query > JRQueryExecuter


1 /*
2  * ============================================================================
3  * GNU Lesser General Public License
4  * ============================================================================
5  *
6  * JasperReports - Free Java report-generating library.
7  * Copyright (C) 2001-2006 JasperSoft Corporation http://www.jaspersoft.com
8  *
9  * 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 /**
35  * Query executer interface.
36  * <p/>
37  * An implementation of this interface is created when the input data of a report/dataset
38  * is specified by a query.
39  * <p/>
40  * The implementation will run the query and create a {@link net.sf.jasperreports.engine.JRDataSource JRDataSource}
41  * from the result.
42  * <p/>
43  * The query executers would usually be initialized by a {@link net.sf.jasperreports.engine.query.JRQueryExecuterFactory JRQueryExecuterFactory}
44  * with the query and the parameter values.
45  *
46  * @author Lucian Chirita (lucianc@users.sourceforge.net)
47  * @version $Id: JRQueryExecuter.java 1229 2006-04-19 13:27:35 +0300 (Wed, 19 Apr 2006) teodord $
48  * @see net.sf.jasperreports.engine.query.JRQueryExecuterFactory
49  */
50 public interface JRQueryExecuter
51 {
52     /**
53      * Executes the query and creates a {@link JRDataSource JRDataSource} out of the result.
54      *
55      * @return a {@link JRDataSource JRDataSource} wrapping the query execution result.
56      * @throws JRException
57      */
58     public JRDataSource createDatasource() throws JRException;
59
60     /**
61      * Closes resources kept open during the data source iteration.
62      * <p/>
63      * This method is called after the report is filled or the dataset is iterated.
64      * If a resource is not needed after the data source has been created, it should be
65      * released at the end of {@link #createDatasource() createDatasource}.
66      */
67     public void close();
68
69     /**
70      * Cancels the query if it's currently running.
71      * <p/>
72      * This method will be called from a different thread if the client decides to
73      * cancel the filling process.
74      *
75      * @return <code>true</code> iff the query was running and it has been cancelled
76      * @throws JRException
77      */
78     public boolean cancelQuery() throws JRException;
79 }
80
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