content: /*
   * Copyright 2002-2018 the original author or authors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package org.springframework.jdbc.core;
  
  import java.sql.Connection;
  import java.sql.SQLException;
  
  import org.springframework.dao.DataAccessException;
  import org.springframework.lang.Nullable;
  
  /**
   * Generic callback interface for code that operates on a JDBC Connection.
   * Allows to execute any number of operations on a single Connection,
   * using any type and number of Statements.
   *
   * <p>This is particularly useful for delegating to existing data access code
   * that expects a Connection to work on and throws SQLException. For newly
   * written code, it is strongly recommended to use JdbcTemplate's more specific
   * operations, for example a {@code query} or {@code update} variant.
   *
   * @author Juergen Hoeller
   * @since 1.1.3
   * @param <T> the result type
   * @see JdbcTemplate#execute(ConnectionCallback)
   * @see JdbcTemplate#query
   * @see JdbcTemplate#update
   */
  @FunctionalInterface
  public interface ConnectionCallback<T> {
  
  	/**
  	 * Gets called by {@code JdbcTemplate.execute} with an active JDBC
  	 * Connection. Does not need to care about activating or closing the
  	 * Connection, or handling transactions.
  	 * <p>If called without a thread-bound JDBC transaction (initiated by
  	 * DataSourceTransactionManager), the code will simply get executed on the
  	 * JDBC connection with its transactional semantics. If JdbcTemplate is
  	 * configured to use a JTA-aware DataSource, the JDBC Connection and thus
  	 * the callback code will be transactional if a JTA transaction is active.
  	 * <p>Allows for returning a result object created within the callback, i.e.
  	 * a domain object or a collection of domain objects. Note that there's special
  	 * support for single step actions: see {@code JdbcTemplate.queryForObject}
  	 * etc. A thrown RuntimeException is treated as application exception:
  	 * it gets propagated to the caller of the template.
  	 * @param con active JDBC Connection
  	 * @return a result object, or {@code null} if none
  	 * @throws SQLException if thrown by a JDBC method, to be auto-converted
  	 * to a DataAccessException by a SQLExceptionTranslator
  	 * @throws DataAccessException in case of custom exceptions
  	 * @see JdbcTemplate#queryForObject(String, Class)
  	 * @see JdbcTemplate#queryForRowSet(String)
  	 */
  	@Nullable
  	T doInConnection(Connection con) throws SQLException, DataAccessException;
  
  }
  