ResultSetExtractor


1   /*
2    * Copyright 2002-2007 the original author or authors.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.springframework.jdbc.core;
18  
19  import java.sql.ResultSet  ;
20  import java.sql.SQLException  ;
21  
22  import org.springframework.dao.DataAccessException;
23  
24  /** 
25   * Callback interface used by {@link JdbcTemplate}'s query methods.
26   * Implementations of this interface perform the actual work of extracting
27   * results from a {@link java.sql.ResultSet}, but don't need to worry
28   * about exception handling. {@link java.sql.SQLException SQLExceptions}
29   * will be caught and handled by the calling JdbcTemplate.
30   *
31   * <p>This interface is mainly used within the JDBC framework itself.
32   * A {@link RowMapper} is usually a simpler choice for ResultSet processing,
33   * mapping one result object per row instead of one result object for
34   * the entire ResultSet.
35   *
36   * <p>Note: In contrast to a {@link RowCallbackHandler}, a ResultSetExtractor
37   * object is typically stateless and thus reusable, as long as it doesn't
38   * access stateful resources (such as output streams when streaming LOB
39   * contents) or keep result state within the object.
40   *
41   * @author Rod Johnson
42   * @author Juergen Hoeller
43   * @since April 24, 2003
44   * @see JdbcTemplate
45   * @see RowCallbackHandler
46   * @see RowMapper
47   * @see org.springframework.jdbc.core.support.AbstractLobStreamingResultSetExtractor
48   */
49  public interface ResultSetExtractor {
50  
51      /**
52       * Implementations must implement this method to process the entire ResultSet.
53       * @param rs ResultSet to extract data from. Implementations should
54       * not close this: it will be closed by the calling JdbcTemplate.
55       * @return an arbitrary result object, or <code>null</code> if none
56       * (the extractor will typically be stateful in the latter case).
57       * @throws SQLException if a SQLException is encountered getting column
58       * values or navigating (that is, there's no need to catch SQLException)
59       * @throws DataAccessException in case of custom exceptions
60       */
61      Object   extractData(ResultSet   rs) throws SQLException  , DataAccessException;
62  
63  }
64
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