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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;
18  
19  import java.sql.ResultSet;
20  import java.sql.SQLException;
21  
22  /**
23   * Defines how to process columns when constructing a bean from a {@link ResultSet}. Instances do the work of retrieving data from a {@code ResultSet}.
24   *
25   * @param <T> The return type.
26   */
27  public interface ColumnHandler<T> {
28  
29      /**
30       * Retrieves the current row's column value from a {@link ResultSet} and stores it into an instance of {@code propType}. This method is only called if
31       * {@link #match(Class)} returns true.
32       *
33       * @param resultSet   The source result set. This must be on the correct row.
34       * @param columnIndex The position of the column to retrieve, a 1-based index.
35       * @return The converted value or the original value if something doesn't work out.
36       * @throws SQLException if the columnIndex is not valid; if a database access error occurs or this method is called on a closed result set
37       */
38      T apply(ResultSet resultSet, int columnIndex) throws SQLException;
39  
40      /**
41       * Tests whether to handle a column targeted for a value type matching {@code propType}.
42       *
43       * @param propType The type of the target parameter.
44       * @return true is this property handler handles this {@code propType}; false otherwise.
45       */
46      boolean match(Class<?> propType);
47  }