01: /*
02: * Licensed to the Apache Software Foundation (ASF) under one or more
03: * contributor license agreements. See the NOTICE file distributed with
04: * this work for additional information regarding copyright ownership.
05: * The ASF licenses this file to You under the Apache License, Version 2.0
06: * (the "License"); you may not use this file except in compliance with
07: * the License. You may obtain a copy of the License at
08: *
09: * http://www.apache.org/licenses/LICENSE-2.0
10: *
11: * Unless required by applicable law or agreed to in writing, software
12: * distributed under the License is distributed on an "AS IS" BASIS,
13: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14: * See the License for the specific language governing permissions and
15: * limitations under the License.
16: */
17: package org.apache.commons.dbutils.handlers;
18:
19: import java.sql.ResultSet;
20: import java.sql.SQLException;
21:
22: import org.apache.commons.dbutils.ResultSetHandler;
23:
24: /**
25: * <code>ResultSetHandler</code> implementation that converts one
26: * <code>ResultSet</code> column into an Object. This class is thread safe.
27: *
28: * @see org.apache.commons.dbutils.ResultSetHandler
29: */
30: public class ScalarHandler implements ResultSetHandler {
31:
32: /**
33: * The column number to retrieve.
34: */
35: private int columnIndex = 1;
36:
37: /**
38: * The column name to retrieve. Either columnName or columnIndex
39: * will be used but never both.
40: */
41: private String columnName = null;
42:
43: /**
44: * Creates a new instance of ScalarHandler. The first column will
45: * be returned from <code>handle()</code>.
46: */
47: public ScalarHandler() {
48: super ();
49: }
50:
51: /**
52: * Creates a new instance of ScalarHandler.
53: *
54: * @param columnIndex The index of the column to retrieve from the
55: * <code>ResultSet</code>.
56: */
57: public ScalarHandler(int columnIndex) {
58: this .columnIndex = columnIndex;
59: }
60:
61: /**
62: * Creates a new instance of ScalarHandler.
63: *
64: * @param columnName The name of the column to retrieve from the
65: * <code>ResultSet</code>.
66: */
67: public ScalarHandler(String columnName) {
68: this .columnName = columnName;
69: }
70:
71: /**
72: * Returns one <code>ResultSet</code> column as an object via the
73: * <code>ResultSet.getObject()</code> method that performs type
74: * conversions.
75: *
76: * @return The column or <code>null</code> if there are no rows in
77: * the <code>ResultSet</code>.
78: *
79: * @throws SQLException if a database access error occurs
80: *
81: * @see org.apache.commons.dbutils.ResultSetHandler#handle(java.sql.ResultSet)
82: */
83: public Object handle(ResultSet rs) throws SQLException {
84:
85: if (rs.next()) {
86: if (this.columnName == null) {
87: return rs.getObject(this.columnIndex);
88: } else {
89: return rs.getObject(this.columnName);
90: }
91:
92: } else {
93: return null;
94: }
95: }
96: }
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