defaultlobhandler.java

来自「spring framework 2.5.4源代码」· Java 代码 · 共 304 行

/*
 * 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.ByteArrayInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.io.StringReader;
import java.io.UnsupportedEncodingException;
import java.sql.Blob;
import java.sql.Clob;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Default implementation of the {@link LobHandler} interface. Invokes
 * the direct accessor methods that <code>java.sql.ResultSet</code>
 * and <code>java.sql.PreparedStatement</code> offer.
 *
 * <p>This LobHandler should work for any JDBC driver that is JDBC compliant
 * in terms of the spec's suggestions regarding simple BLOB and CLOB handling.
 * This does not apply to Oracle 9i, and only to a limited degree to Oracle 10g!
 * As a consequence, use {@link OracleLobHandler} for accessing Oracle BLOBs/CLOBs.
 *
 * <p>Some JDBC drivers require values with a BLOB/CLOB target column to be
 * explicitly set through the JDBC <code>setBlob</code> / <code>setClob</code>
 * API: for example, PostgreSQL's driver. Switch the {@link #setWrapAsLob "wrapAsLob"}
 * property to "true" when operating against such a driver.
 *
 * <p>On JDBC 4.0, this LobHandler also supports streaming the BLOB/CLOB content
 * via the <code>setBlob</code> / <code>setClob</code> variants that take a stream
 * argument directly. Consider switching the {@link #setStreamAsLob "streamAsLob"}
 * property to "true" when operating against a fully compliant JDBC 4.0 driver.
 *
 * <p>See the {@link LobHandler} javadoc for a summary of recommendations.
 *
 * @author Juergen Hoeller
 * @since 04.12.2003
 * @see #setStreamAsLob
 * @see java.sql.ResultSet#getBytes
 * @see java.sql.ResultSet#getBinaryStream
 * @see java.sql.ResultSet#getString
 * @see java.sql.ResultSet#getAsciiStream
 * @see java.sql.ResultSet#getCharacterStream
 * @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 class DefaultLobHandler extends AbstractLobHandler {

	protected final Log logger = LogFactory.getLog(getClass());

	private boolean wrapAsLob = false;

	private boolean streamAsLob = false;


	/**
	 * Specify whether to submit a byte array / String to the JDBC driver
	 * wrapped in a JDBC Blob / Clob object, using the JDBC <code>setBlob</code> /
	 * <code>setClob</code> method with a Blob / Clob argument.
	 * <p>Default is "false", using the common JDBC 2.0 <code>setBinaryStream</code>
	 * / <code>setCharacterStream</code> method for setting the content.
	 * Switch this to "true" for explicit Blob / Clob wrapping against
	 * JDBC drivers that are known to require such wrapping (e.g. PostgreSQL's).
	 * <p>This setting affects byte array / String arguments as well as stream
	 * arguments, unless {@link #setStreamAsLob "streamAsLob"} overrides this
	 * handling to use JDBC 4.0's new explicit streaming support (if available).
	 * @see java.sql.PreparedStatement#setBlob(int, java.sql.Blob)
	 * @see java.sql.PreparedStatement#setClob(int, java.sql.Clob)
	 */
	public void setWrapAsLob(boolean wrapAsLob) {
		this.wrapAsLob = wrapAsLob;
	}

	/**
	 * Specify whether to submit a binary stream / character stream to the JDBC
	 * driver as explicit LOB content, using the JDBC 4.0 <code>setBlob</code> /
	 * <code>setClob</code> method with a stream argument.
	 * <p>Default is "false", using the common JDBC 2.0 <code>setBinaryStream</code>
	 * / <code>setCharacterStream</code> method for setting the content.
	 * Switch this to "true" for explicit JDBC 4.0 usage, provided that your
	 * JDBC driver actually supports those JDBC 4.0 operations (e.g. Derby's).
	 * <p>This setting affects stream arguments as well as byte array / String
	 * arguments, requiring JDBC 4.0 support. For supporting LOB content against
	 * JDBC 3.0, check out the {@link #setWrapAsLob "wrapAsLob"} setting.
	 * @see java.sql.PreparedStatement#setBlob(int, java.io.InputStream, long)
	 * @see java.sql.PreparedStatement#setClob(int, java.io.Reader, long)
	 */
	public void setStreamAsLob(boolean streamAsLob) {
		this.streamAsLob = streamAsLob;
	}


	public byte[] getBlobAsBytes(ResultSet rs, int columnIndex) throws SQLException {
		logger.debug("Returning BLOB as bytes");
		return rs.getBytes(columnIndex);
	}

	public InputStream getBlobAsBinaryStream(ResultSet rs, int columnIndex) throws SQLException {
		logger.debug("Returning BLOB as binary stream");
		return rs.getBinaryStream(columnIndex);
	}

	public String getClobAsString(ResultSet rs, int columnIndex) throws SQLException {
		logger.debug("Returning CLOB as string");
		return rs.getString(columnIndex);
	}

	public InputStream getClobAsAsciiStream(ResultSet rs, int columnIndex) throws SQLException {
		logger.debug("Returning CLOB as ASCII stream");
		return rs.getAsciiStream(columnIndex);
	}

	public Reader getClobAsCharacterStream(ResultSet rs, int columnIndex) throws SQLException {
		logger.debug("Returning CLOB as character stream");
		return rs.getCharacterStream(columnIndex);
	}

	public LobCreator getLobCreator() {
		return new DefaultLobCreator();
	}


	/**
	 * Default LobCreator implementation as inner class.
	 * Can be subclassed in DefaultLobHandler extensions.
	 */
	protected class DefaultLobCreator implements LobCreator {

		public void setBlobAsBytes(PreparedStatement ps, int paramIndex, byte[] content)
				throws SQLException {

			if (streamAsLob) {
				if (content != null) {
					ps.setBlob(paramIndex, new ByteArrayInputStream(content), content.length);
				}
				else {
					ps.setBlob(paramIndex, (Blob) null);
				}
			}
			else if (wrapAsLob) {
				if (content != null) {
					ps.setBlob(paramIndex, new PassThroughBlob(content));
				}
				else {
					ps.setBlob(paramIndex, (Blob) null);
				}
			}
			else {
				ps.setBytes(paramIndex, content);
			}
			if (logger.isDebugEnabled()) {
				logger.debug(content != null ? "Set bytes for BLOB with length " + content.length :
						"Set BLOB to null");
			}
		}

		public void setBlobAsBinaryStream(
				PreparedStatement ps, int paramIndex, InputStream binaryStream, int contentLength)
				throws SQLException {

			if (streamAsLob) {
				if (binaryStream != null) {
					ps.setBlob(paramIndex, binaryStream, contentLength);
				}
				else {
					ps.setBlob(paramIndex, (Blob) null);
				}
			}
			else if (wrapAsLob) {
				if (binaryStream != null) {
					ps.setBlob(paramIndex, new PassThroughBlob(binaryStream, contentLength));
				}
				else {
					ps.setBlob(paramIndex, (Blob) null);
				}
			}
			else {
				ps.setBinaryStream(paramIndex, binaryStream, contentLength);
			}
			if (logger.isDebugEnabled()) {
				logger.debug(binaryStream != null ? "Set binary stream for BLOB with length " + contentLength :
						"Set BLOB to null");
			}
		}

		public void setClobAsString(PreparedStatement ps, int paramIndex, String content)
		    throws SQLException {

			if (streamAsLob) {
				if (content != null) {
					ps.setClob(paramIndex, new StringReader(content), content.length());
				}
				else {
					ps.setClob(paramIndex, (Clob) null);
				}
			}
			else if (wrapAsLob) {
				if (content != null) {
					ps.setClob(paramIndex, new PassThroughClob(content));
				}
				else {
					ps.setClob(paramIndex, (Clob) null);
				}
			}
			else {
				ps.setString(paramIndex, content);
			}
			if (logger.isDebugEnabled()) {
				logger.debug(content != null ? "Set string for CLOB with length " + content.length() :
						"Set CLOB to null");
			}
		}

		public void setClobAsAsciiStream(
				PreparedStatement ps, int paramIndex, InputStream asciiStream, int contentLength)
		    throws SQLException {

			if (streamAsLob || wrapAsLob) {
				if (asciiStream != null) {
					try {
						Reader reader = new InputStreamReader(asciiStream, "US-ASCII");
						if (streamAsLob) {
							ps.setClob(paramIndex, reader, contentLength);
						}
						else {
							ps.setClob(paramIndex, new PassThroughClob(reader, contentLength));
						}
					}
					catch (UnsupportedEncodingException ex) {
						throw new SQLException("US-ASCII encoding not supported: " + ex);
					}
				}
				else {
					ps.setClob(paramIndex, (Clob) null);
				}
			}
			else {
				ps.setAsciiStream(paramIndex, asciiStream, contentLength);
			}
			if (logger.isDebugEnabled()) {
				logger.debug(asciiStream != null ? "Set ASCII stream for CLOB with length " + contentLength :
						"Set CLOB to null");
			}
		}

		public void setClobAsCharacterStream(
				PreparedStatement ps, int paramIndex, Reader characterStream, int contentLength)
		    throws SQLException {

			if (streamAsLob) {
				if (characterStream != null) {
					ps.setClob(paramIndex, characterStream, contentLength);
				}
				else {
					ps.setClob(paramIndex, (Clob) null);
				}
			}
			else if (wrapAsLob) {
				if (characterStream != null) {
					ps.setClob(paramIndex, new PassThroughClob(characterStream, contentLength));
				}
				else {
					ps.setClob(paramIndex, (Clob) null);
				}
			}
			else {
				ps.setCharacterStream(paramIndex, characterStream, contentLength);
			}
			if (logger.isDebugEnabled()) {
				logger.debug(characterStream != null ? "Set character stream for CLOB with length " + contentLength :
						"Set CLOB to null");
			}
		}

		public void close() {
			// nothing to do here
		}
	}

}