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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      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  /**
23   * <code>ResultSetHandler</code> implementation that converts one
24   * <code>ResultSet</code> column into a <code>List</code> of
25   * <code>Object</code>s. This class is thread safe.
26   * 
27   * @see org.apache.commons.dbutils.ResultSetHandler
28   * @since DbUtils 1.1
29   */
30  public class ColumnListHandler extends AbstractListHandler {
31  
32      /**
33       * The column number to retrieve.
34       */
35      private final int columnIndex;
36  
37      /**
38       * The column name to retrieve.  Either columnName or columnIndex
39       * will be used but never both.
40       */
41      private final String columnName;
42  
43      /** 
44       * Creates a new instance of ColumnListHandler.  The first column of each
45       * row will be returned from <code>handle()</code>.
46       */
47      public ColumnListHandler() {
48          this(1, null);
49      }
50  
51      /** 
52       * Creates a new instance of ColumnListHandler.
53       * 
54       * @param columnIndex The index of the column to retrieve from the 
55       * <code>ResultSet</code>.
56       */
57      public ColumnListHandler(int columnIndex) {
58          this(columnIndex, null);
59      }
60  
61      /** 
62       * Creates a new instance of ColumnListHandler.
63       * 
64       * @param columnName The name of the column to retrieve from the 
65       * <code>ResultSet</code>.
66       */
67      public ColumnListHandler(String columnName) {
68          this(1, columnName);
69      }
70  
71      // Helper
72      private ColumnListHandler(int columnIndex, String columnName) {
73          super();
74          this.columnIndex = columnIndex;
75          this.columnName = columnName;        
76      }
77      
78      /**
79       * Returns one <code>ResultSet</code> column value as <code>Object</code>.
80       * 
81       * @return <code>Object</code>, never <code>null</code>.
82       * 
83       * @throws SQLException if a database access error occurs
84       * 
85       * @see org.apache.commons.dbutils.handlers.AbstractListHandler#handle(ResultSet)
86       */
87     protected Object handleRow(ResultSet rs) throws SQLException {
88          if (this.columnName == null) {
89              return rs.getObject(this.columnIndex);
90          } else {
91              return rs.getObject(this.columnName);
92          }
93     }
94  
95  }