spring DefaultLobHandler 源码
spring DefaultLobHandler 代码
文件路径：/spring-jdbc/src/main/java/org/springframework/jdbc/support/lob/DefaultLobHandler.java
/*
* Copyright 2002-2017 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
*
* https://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.nio.charset.StandardCharsets;
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;
import org.springframework.lang.Nullable;
/**
* Default implementation of the {@link LobHandler} interface.
* Invokes the direct accessor methods that {@code java.sql.ResultSet}
* and {@code java.sql.PreparedStatement} offer.
*
* <p>By default, incoming streams are going to be passed to the appropriate
* {@code setBinary/Ascii/CharacterStream} method on the JDBC driver's
* {@link PreparedStatement}. If the specified content length is negative,
* this handler will use the JDBC 4.0 variants of the set-stream methods
* without a length parameter; otherwise, it will pass the specified length
* on to the driver.
*
* <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's drivers at all; as of Oracle 10g,
* it does work but may still come with LOB size limitations. Consider using
* recent Oracle drivers even when working against an older database server.
* See the {@link LobHandler} javadoc for the full set of recommendations.
*
* <p>Some JDBC drivers require values with a BLOB/CLOB target column to be
* explicitly set through the JDBC {@code setBlob} / {@code setClob} 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 setClob} 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>Finally, this LobHandler also supports the creation of temporary BLOB/CLOB
* objects. Consider switching the {@link #setCreateTemporaryLob "createTemporaryLob"}
* property to "true" when "streamAsLob" happens to run into LOB size limitations.
*
* <p>See the {@link LobHandler} interface javadoc for a summary of recommendations.
*
* @author Juergen Hoeller
* @since 04.12.2003
* @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;
private boolean createTemporaryLob = 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 setClob} method with a Blob / Clob argument.
* <p>Default is "false", using the common JDBC 2.0 {@code setBinaryStream}
* / {@code setCharacterStream} 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 for access to OID
* columns, whereas BYTEA columns need to be accessed the standard way).
* <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 setClob} method with a stream argument.
* <p>Default is "false", using the common JDBC 2.0 {@code setBinaryStream}
* / {@code setCharacterStream} method for setting the content.
* Switch this to "true" for explicit JDBC 4.0 streaming, 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;
}
/**
* Specify whether to copy a byte array / String into a temporary JDBC
* Blob / Clob object created through the JDBC 4.0 {@code createBlob} /
* {@code createClob} methods.
* <p>Default is "false", using the common JDBC 2.0 {@code setBinaryStream}
* / {@code setCharacterStream} method for setting the content. Switch this
* to "true" for explicit Blob / Clob creation using JDBC 4.0.
* <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.Connection#createBlob()
* @see java.sql.Connection#createClob()
*/
public void setCreateTemporaryLob(boolean createTemporaryLob) {
this.createTemporaryLob = createTemporaryLob;
}
@Override
@Nullable
public byte[] getBlobAsBytes(ResultSet rs, int columnIndex) throws SQLException {
logger.debug("Returning BLOB as bytes");
if (this.wrapAsLob) {
Blob blob = rs.getBlob(columnIndex);
return blob.getBytes(1, (int) blob.length());
}
else {
return rs.getBytes(columnIndex);
}
}
@Override
@Nullable
public InputStream getBlobAsBinaryStream(ResultSet rs, int columnIndex) throws SQLException {
logger.debug("Returning BLOB as binary stream");
if (this.wrapAsLob) {
Blob blob = rs.getBlob(columnIndex);
return blob.getBinaryStream();
}
else {
return rs.getBinaryStream(columnIndex);
}
}
@Override
@Nullable
public String getClobAsString(ResultSet rs, int columnIndex) throws SQLException {
logger.debug("Returning CLOB as string");
if (this.wrapAsLob) {
Clob clob = rs.getClob(columnIndex);
return clob.getSubString(1, (int) clob.length());
}
else {
return rs.getString(columnIndex);
}
}
@Override
public InputStream getClobAsAsciiStream(ResultSet rs, int columnIndex) throws SQLException {
logger.debug("Returning CLOB as ASCII stream");
if (this.wrapAsLob) {
Clob clob = rs.getClob(columnIndex);
return clob.getAsciiStream();
}
else {
return rs.getAsciiStream(columnIndex);
}
}
@Override
public Reader getClobAsCharacterStream(ResultSet rs, int columnIndex) throws SQLException {
logger.debug("Returning CLOB as character stream");
if (this.wrapAsLob) {
Clob clob = rs.getClob(columnIndex);
return clob.getCharacterStream();
}
else {
return rs.getCharacterStream(columnIndex);
}
}
@Override
public LobCreator getLobCreator() {
return (this.createTemporaryLob ? new TemporaryLobCreator() : new DefaultLobCreator());
}
/**
* Default LobCreator implementation as an inner class.
* Can be subclassed in DefaultLobHandler extensions.
*/
protected class DefaultLobCreator implements LobCreator {
@Override
public void setBlobAsBytes(PreparedStatement ps, int paramIndex, @Nullable 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");
}
}
@Override
public void setBlobAsBinaryStream(
PreparedStatement ps, int paramIndex, @Nullable InputStream binaryStream, int contentLength)
throws SQLException {
if (streamAsLob) {
if (binaryStream != null) {
if (contentLength >= 0) {
ps.setBlob(paramIndex, binaryStream, contentLength);
}
else {
ps.setBlob(paramIndex, binaryStream);
}
}
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 if (contentLength >= 0) {
ps.setBinaryStream(paramIndex, binaryStream, contentLength);
}
else {
ps.setBinaryStream(paramIndex, binaryStream);
}
if (logger.isDebugEnabled()) {
logger.debug(binaryStream != null ? "Set binary stream for BLOB with length " + contentLength :
"Set BLOB to null");
}
}
@Override
public void setClobAsString(PreparedStatement ps, int paramIndex, @Nullable 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");
}
}
@Override
public void setClobAsAsciiStream(
PreparedStatement ps, int paramIndex, @Nullable InputStream asciiStream, int contentLength)
throws SQLException {
if (streamAsLob) {
if (asciiStream != null) {
Reader reader = new InputStreamReader(asciiStream, StandardCharsets.US_ASCII);
if (contentLength >= 0) {
ps.setClob(paramIndex, reader, contentLength);
}
else {
ps.setClob(paramIndex, reader);
}
}
else {
ps.setClob(paramIndex, (Clob) null);
}
}
else if (wrapAsLob) {
if (asciiStream != null) {
ps.setClob(paramIndex, new PassThroughClob(asciiStream, contentLength));
}
else {
ps.setClob(paramIndex, (Clob) null);
}
}
else if (contentLength >= 0) {
ps.setAsciiStream(paramIndex, asciiStream, contentLength);
}
else {
ps.setAsciiStream(paramIndex, asciiStream);
}
if (logger.isDebugEnabled()) {
logger.debug(asciiStream != null ? "Set ASCII stream for CLOB with length " + contentLength :
"Set CLOB to null");
}
}
@Override
public void setClobAsCharacterStream(
PreparedStatement ps, int paramIndex, @Nullable Reader characterStream, int contentLength)
throws SQLException {
if (streamAsLob) {
if (characterStream != null) {
if (contentLength >= 0) {
ps.setClob(paramIndex, characterStream, contentLength);
}
else {
ps.setClob(paramIndex, characterStream);
}
}
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 if (contentLength >= 0) {
ps.setCharacterStream(paramIndex, characterStream, contentLength);
}
else {
ps.setCharacterStream(paramIndex, characterStream);
}
if (logger.isDebugEnabled()) {
logger.debug(characterStream != null ? "Set character stream for CLOB with length " + contentLength :
"Set CLOB to null");
}
}
@Override
public void close() {
// nothing to do when not creating temporary LOBs
}
}
}
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