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Java > Open Source Codes > org > apache > commons > dbutils > handlers > ScalarHandler


1 /*
2  * $Header: /home/cvs/jakarta-commons/dbutils/src/java/org/apache/commons/dbutils/handlers/ScalarHandler.java,v 1.1 2003/11/02 19:15:24 dgraham Exp $
3  * $Revision: 1.1 $
4  * $Date: 2003/11/02 19:15:24 $
5  *
6  * ====================================================================
7  *
8  * The Apache Software License, Version 1.1
9  *
10  * Copyright (c) 2003 The Apache Software Foundation. All rights
11  * reserved.
12  *
13  * Redistribution and use in source and binary forms, with or without
14  * modification, are permitted provided that the following conditions
15  * are met:
16  *
17  * 1. Redistributions of source code must retain the above copyright
18  * notice, this list of conditions and the following disclaimer.
19  *
20  * 2. Redistributions in binary form must reproduce the above copyright
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22  * the documentation and/or other materials provided with the
23  * distribution.
24  *
25  * 3. The end-user documentation included with the redistribution, if
26  * any, must include the following acknowledgement:
27  * "This product includes software developed by the
28  * Apache Software Foundation (http://www.apache.org/)."
29  * Alternately, this acknowledgement may appear in the software itself,
30  * if and wherever such third-party acknowledgements normally appear.
31  *
32  * 4. The names "The Jakarta Project", "Commons", and "Apache Software
33  * Foundation" must not be used to endorse or promote products derived
34  * from this software without prior written permission. For written
35  * permission, please contact apache@apache.org.
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37  * 5. Products derived from this software may not be called "Apache"
38  * nor may "Apache" appear in their names without prior written
39  * permission of the Apache Software Foundation.
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41  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
42  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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47  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
48  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
49  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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52  * SUCH DAMAGE.
53  * ====================================================================
54  *
55  * This software consists of voluntary contributions made by many
56  * individuals on behalf of the Apache Software Foundation. For more
57  * information on the Apache Software Foundation, please see
58  * <http://www.apache.org/>.
59  *
60  */
61
62 package org.apache.commons.dbutils.handlers;
63
64 import java.sql.ResultSet JavaDoc;
65 import java.sql.SQLException JavaDoc;
66
67 import org.apache.commons.dbutils.ResultSetHandler;
68
69 /**
70  * <code>ResultSetHandler</code> implementation that converts one
71  * <code>ResultSet</code> column into an Object. This class is thread safe.
72  *
73  * @see ResultSetHandler
74  * @author Juozas Baliuka
75  * @author David Graham
76  */
77 public class ScalarHandler implements ResultSetHandler {
78
79     /**
80      * The column number to retrieve.
81      */
82     private int columnIndex = 1;
83
84     /**
85      * The column name to retrieve. Either columnName or columnIndex
86      * will be used but never both.
87      */
88     private String JavaDoc columnName = null;
89
90     /**
91      * Creates a new instance of ScalarHandler. The first column will
92      * be returned from <code>handle()</code>.
93      */
94     public ScalarHandler() {
95         super();
96     }
97
98     /**
99      * Creates a new instance of ScalarHandler.
100      *
101      * @param columnIndex The index of the column to retrieve from the
102      * <code>ResultSet</code>.
103      */
104     public ScalarHandler(int columnIndex) {
105         this.columnIndex = columnIndex;
106     }
107
108     /**
109      * Creates a new instance of ScalarHandler.
110      *
111      * @param columnName The name of the column to retrieve from the
112      * <code>ResultSet</code>.
113      */
114     public ScalarHandler(String JavaDoc columnName) {
115         this.columnName = columnName;
116     }
117
118     /**
119      * Returns one <code>ResultSet</code> column as an object via the
120      * <code>ResultSet.getObject()</code> method that performs type
121      * conversions.
122      *
123      * @return The column or <code>null</code> if there are no rows in
124      * the <code>ResultSet</code>.
125      *
126      * @throws SQLException
127      *
128      * @see org.apache.commons.dbutils.ResultSetHandler#handle(java.sql.ResultSet)
129      */
130     public Object JavaDoc handle(ResultSet JavaDoc rs) throws SQLException JavaDoc {
131
132         if (rs.next()) {
133             if (this.columnName == null) {
134                 return rs.getObject(this.columnIndex);
135             } else {
136                 return rs.getObject(this.columnName);
137             }
138
139         } else {
140             return null;
141         }
142     }
143 }
144
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