/*
 * Copyright 2002-2008 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.support.lob;

import java.io.InputStream;
import java.io.Reader;
import java.sql.PreparedStatement;
import java.sql.SQLException;

/**
 * Interface that abstracts potentially database-specific creation of large binary
 * fields and large text fields. Does not work with <code>java.sql.Blob</code>
 * and <code>java.sql.Clob</code> instances in the API, as some JDBC drivers
 * do not support these types as such.
 *
 * <p>The LOB creation part is where {@link LobHandler} implementations usually
 * differ. Possible strategies include usage of
 * <code>PreparedStatement.setBinaryStream/setCharacterStream</code> but also
 * <code>PreparedStatement.setBlob/setClob</code> with either a stream argument
 * (requires JDBC 4.0) or <code>java.sql.Blob/Clob</code> wrapper objects.
 *
 * <p>A LobCreator represents a session for creating BLOBs: It is <i>not</i>
 * thread-safe and needs to be instantiated for each statement execution or for
 * each transaction. Each LobCreator needs to be closed after completion.
 *
 * <p>For convenient working with a PreparedStatement and a LobCreator,
 * consider using {@link org.springframework.jdbc.core.JdbcTemplate} with an
 *{@link org.springframework.jdbc.core.support.AbstractLobCreatingPreparedStatementCallback}
 * implementation. See the latter's javadoc for details.
 *
 * @author Juergen Hoeller
 * @since 04.12.2003
 * @see #close()
 * @see LobHandler#getLobCreator()
 * @see DefaultLobHandler.DefaultLobCreator
 * @see OracleLobHandler.OracleLobCreator
 * @see java.sql.PreparedStatement#setBlob
 * @see java.sql.PreparedStatement#setClob
 * @see java.sql.PreparedStatement#setBytes
 * @see java.sql.PreparedStatement#setBinaryStream
 * @see java.sql.PreparedStatement#setString
 * @see java.sql.PreparedStatement#setAsciiStream
 * @see java.sql.PreparedStatement#setCharacterStream
 */
public interface LobCreator {

	/**
	 * Set the given content as bytes on the given statement, using the given
	 * parameter index. Might simply invoke <code>PreparedStatement.setBytes</code>
	 * or create a Blob instance for it, depending on the database and driver.
	 * @param ps the PreparedStatement to the set the content on
	 * @param paramIndex the parameter index to use
	 * @param content the content as byte array, or <code>null</code> for SQL NULL
	 * @throws SQLException if thrown by JDBC methods
	 * @see java.sql.PreparedStatement#setBytes
	 */
	void setBlobAsBytes(PreparedStatement ps, int paramIndex, byte[] content)
	    throws SQLException;

	/**
	 * Set the given content as binary stream on the given statement, using the given
	 * parameter index. Might simply invoke <code>PreparedStatement.setBinaryStream</code>
	 * or create a Blob instance for it, depending on the database and driver.
	 * @param ps the PreparedStatement to the set the content on
	 * @param paramIndex the parameter index to use
	 * @param contentStream the content as binary stream, or <code>null</code> for SQL NULL
	 * @throws SQLException if thrown by JDBC methods
	 * @see java.sql.PreparedStatement#setBinaryStream
	 */
	void setBlobAsBinaryStream(
			PreparedStatement ps, int paramIndex, InputStream contentStream, int contentLength)
	    throws SQLException;

	/**
	 * Set the given content as String on the given statement, using the given
	 * parameter index. Might simply invoke <code>PreparedStatement.setString</code>
	 * or create a Clob instance for it, depending on the database and driver.
	 * @param ps the PreparedStatement to the set the content on
	 * @param paramIndex the parameter index to use
	 * @param content the content as String, or <code>null</code> for SQL NULL
	 * @throws SQLException if thrown by JDBC methods
	 * @see java.sql.PreparedStatement#setBytes
	 */
	void setClobAsString(PreparedStatement ps, int paramIndex, String content)
	    throws SQLException;

	/**
	 * Set the given content as ASCII stream on the given statement, using the given
	 * parameter index. Might simply invoke <code>PreparedStatement.setAsciiStream</code>
	 * or create a Clob instance for it, depending on the database and driver.
	 * @param ps the PreparedStatement to the set the content on
	 * @param paramIndex the parameter index to use
	 * @param asciiStream the content as ASCII stream, or <code>null</code> for SQL NULL
	 * @throws SQLException if thrown by JDBC methods
	 * @see java.sql.PreparedStatement#setAsciiStream
	 */
	void setClobAsAsciiStream(
			PreparedStatement ps, int paramIndex, InputStream asciiStream, int contentLength)
	    throws SQLException;

	/**
	 * Set the given content as character stream on the given statement, using the given
	 * parameter index. Might simply invoke <code>PreparedStatement.setCharacterStream</code>
	 * or create a Clob instance for it, depending on the database and driver.
	 * @param ps the PreparedStatement to the set the content on
	 * @param paramIndex the parameter index to use
	 * @param characterStream the content as character stream, or <code>null</code> for SQL NULL
	 * @throws SQLException if thrown by JDBC methods
	 * @see java.sql.PreparedStatement#setCharacterStream
	 */
	void setClobAsCharacterStream(
			PreparedStatement ps, int paramIndex, Reader characterStream, int contentLength)
	    throws SQLException;

	/**
	 * Close this LobCreator session and free its temporarily created BLOBs and CLOBs.
	 * Will not need to do anything if using PreparedStatement's standard methods,
	 * but might be necessary to free database resources if using proprietary means.
	 * <p><b>NOTE</b>: Needs to be invoked after the involved PreparedStatements have
	 * been executed or the affected O/R mapping sessions have been flushed.
	 * Otherwise, the database resources for the temporary BLOBs might stay allocated.
	 */
	void close();

}