added a "releaseResourcesAfterRead" property defaulting to false and code to handle releasing any LOB resources after read if requested (SPR-5998, SPR-6209)
This commit is contained in:
Thomas Risberg
parent
d9aab1079c
commit
5a158fb76f
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@ -64,12 +64,13 @@ import org.springframework.util.FileCopyUtils;
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*
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* <p>Coded via reflection to avoid dependencies on Oracle classes.
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* Even reads in Oracle constants via reflection because of different Oracle
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* drivers (classes12, ojdbc14) having different constant values! As this
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* LobHandler initializes Oracle classes on instantiation, do not define this
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* as eager-initializing singleton if you do not want to depend on the Oracle
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* drivers (classes12, ojdbc14, ojdbc5, ojdbc6) having different constant values!
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* As this LobHandler initializes Oracle classes on instantiation, do not define
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* this as eager-initializing singleton if you do not want to depend on the Oracle
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* JAR being in the class path: use "lazy-init=true" to avoid this issue.
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*
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* @author Juergen Hoeller
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* @author Thomas Risberg
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* @since 04.12.2003
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* @see #setNativeJdbcExtractor
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* @see oracle.sql.BLOB
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@ -85,6 +86,8 @@ public class OracleLobHandler extends AbstractLobHandler {
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private static final String MODE_READWRITE_FIELD_NAME = "MODE_READWRITE";
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private static final String MODE_READONLY_FIELD_NAME = "MODE_READONLY";
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protected final Log logger = LogFactory.getLog(getClass());
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@ -92,6 +95,8 @@ public class OracleLobHandler extends AbstractLobHandler {
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private Boolean cache = Boolean.TRUE;
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private Boolean releaseResourcesAfterRead = Boolean.FALSE;
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private Class blobClass;
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private Class clobClass;
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@ -100,6 +105,8 @@ public class OracleLobHandler extends AbstractLobHandler {
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private final Map<Class, Integer> modeReadWriteConstants = new HashMap<Class, Integer>(2);
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private final Map<Class, Integer> modeReadOnlyConstants = new HashMap<Class, Integer>(2);
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/**
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* Set an appropriate NativeJdbcExtractor to be able to retrieve the underlying
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@ -123,7 +130,9 @@ public class OracleLobHandler extends AbstractLobHandler {
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/**
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* Set whether to cache the temporary LOB in the buffer cache.
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* This value will be passed into BLOB/CLOB.createTemporary. Default is "true".
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* This value will be passed into BLOB/CLOB.createTemporary.
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*
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* <p>Default is <code>true</code>.
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* @see oracle.sql.BLOB#createTemporary
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* @see oracle.sql.CLOB#createTemporary
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*/
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@ -131,17 +140,42 @@ public class OracleLobHandler extends AbstractLobHandler {
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this.cache = cache;
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}
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/**
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* Set whether to agressively release any resources used by the LOB. If set to <code>true</code>
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* then you can only read the LOB values once. Any subsequent reads will fail since the resources
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* have been closed.
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*
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* <p>Setting this property to <code>true</code> can be useful when your queries generates large
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* temporary LOBs that occupy space in the TEMPORARY tablespace or when you want to free up any
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* memory allocated by the driver for the LOB reading.
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*
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* <p>Default is <code>false</code>.
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*
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* @see oracle.sql.BLOB#freeTemporary
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* @see oracle.sql.CLOB#freeTemporary
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* @see oracle.sql.BLOB#open
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* @see oracle.sql.CLOB#open
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* @see oracle.sql.BLOB#close
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* @see oracle.sql.CLOB#close
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* @since 3.0
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*/
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public void setReleaseResourcesAfterRead(boolean releaseResources) {
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this.releaseResourcesAfterRead = releaseResources;
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}
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/**
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* Retrieve the <code>oracle.sql.BLOB</code> and <code>oracle.sql.CLOB</code>
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* classes via reflection, and initialize the values for the
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* DURATION_SESSION and MODE_READWRITE constants defined there.
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* DURATION_SESSION, MODE_READWRITE and MODE_READONLY constants defined there.
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* @param con the Oracle Connection, for using the exact same class loader
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* that the Oracle driver was loaded with
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* @see oracle.sql.BLOB#DURATION_SESSION
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* @see oracle.sql.BLOB#MODE_READWRITE
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* @see oracle.sql.BLOB#MODE_READONLY
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* @see oracle.sql.CLOB#DURATION_SESSION
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* @see oracle.sql.CLOB#MODE_READWRITE
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* @see oracle.sql.CLOB#MODE_READONLY
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*/
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protected synchronized void initOracleDriverClasses(Connection con) {
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if (this.blobClass == null) {
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@ -152,6 +186,8 @@ public class OracleLobHandler extends AbstractLobHandler {
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this.blobClass, this.blobClass.getField(DURATION_SESSION_FIELD_NAME).getInt(null));
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this.modeReadWriteConstants.put(
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this.blobClass, this.blobClass.getField(MODE_READWRITE_FIELD_NAME).getInt(null));
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this.modeReadOnlyConstants.put(
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this.blobClass, this.blobClass.getField(MODE_READONLY_FIELD_NAME).getInt(null));
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// Initialize oracle.sql.CLOB class
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this.clobClass = con.getClass().getClassLoader().loadClass(CLOB_CLASS_NAME);
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@ -159,6 +195,8 @@ public class OracleLobHandler extends AbstractLobHandler {
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this.clobClass, this.clobClass.getField(DURATION_SESSION_FIELD_NAME).getInt(null));
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this.modeReadWriteConstants.put(
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this.clobClass, this.clobClass.getField(MODE_READWRITE_FIELD_NAME).getInt(null));
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this.modeReadOnlyConstants.put(
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this.clobClass, this.clobClass.getField(MODE_READONLY_FIELD_NAME).getInt(null));
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}
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catch (Exception ex) {
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throw new InvalidDataAccessApiUsageException(
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@ -172,37 +210,153 @@ public class OracleLobHandler extends AbstractLobHandler {
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public byte[] getBlobAsBytes(ResultSet rs, int columnIndex) throws SQLException {
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logger.debug("Returning Oracle BLOB as bytes");
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Blob blob = rs.getBlob(columnIndex);
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return (blob != null ? blob.getBytes(1, (int) blob.length()) : null);
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initializeResourcesBeforeRead(rs.getStatement().getConnection(), blob);
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byte[] retVal = (blob != null ? blob.getBytes(1, (int) blob.length()) : null);
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releaseResourcesAfterRead(rs.getStatement().getConnection(), blob);
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return retVal;
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}
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public InputStream getBlobAsBinaryStream(ResultSet rs, int columnIndex) throws SQLException {
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logger.debug("Returning Oracle BLOB as binary stream");
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Blob blob = rs.getBlob(columnIndex);
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return (blob != null ? blob.getBinaryStream() : null);
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initializeResourcesBeforeRead(rs.getStatement().getConnection(), blob);
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InputStream retVal = (blob != null ? blob.getBinaryStream() : null);
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releaseResourcesAfterRead(rs.getStatement().getConnection(), blob);
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return retVal;
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}
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public String getClobAsString(ResultSet rs, int columnIndex) throws SQLException {
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logger.debug("Returning Oracle CLOB as string");
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Clob clob = rs.getClob(columnIndex);
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return (clob != null ? clob.getSubString(1, (int) clob.length()) : null);
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initializeResourcesBeforeRead(rs.getStatement().getConnection(), clob);
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String retVal = (clob != null ? clob.getSubString(1, (int) clob.length()) : null);
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releaseResourcesAfterRead(rs.getStatement().getConnection(), clob);
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return retVal;
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}
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public InputStream getClobAsAsciiStream(ResultSet rs, int columnIndex) throws SQLException {
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logger.debug("Returning Oracle CLOB as ASCII stream");
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Clob clob = rs.getClob(columnIndex);
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return (clob != null ? clob.getAsciiStream() : null);
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initializeResourcesBeforeRead(rs.getStatement().getConnection(), clob);
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InputStream retVal = (clob != null ? clob.getAsciiStream() : null);
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releaseResourcesAfterRead(rs.getStatement().getConnection(), clob);
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return retVal;
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}
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public Reader getClobAsCharacterStream(ResultSet rs, int columnIndex) throws SQLException {
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logger.debug("Returning Oracle CLOB as character stream");
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Clob clob = rs.getClob(columnIndex);
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return (clob != null ? clob.getCharacterStream() : null);
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initializeResourcesBeforeRead(rs.getStatement().getConnection(), clob);
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Reader retVal = (clob != null ? clob.getCharacterStream() : null);
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releaseResourcesAfterRead(rs.getStatement().getConnection(), clob);
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return retVal;
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}
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public LobCreator getLobCreator() {
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return new OracleLobCreator();
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}
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/**
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* Initialize any LOB resources before a read is done.
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*
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* <p>This implementation calls
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* <code>BLOB.open(BLOB.MODE_READONLY)</code> or <code>CLOB.open(CLOB.MODE_READONLY)</code>
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* on any non-temporary LOBs
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* if <code>releaseResourcesAfterRead</code> property is set to <code>true</code>.
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* <p>This method can be overridden by sublcasses if different behavior is desired.
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* @param con the connection to be usde for initilization
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* @param lob the LOB to initialize
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*/
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protected void initializeResourcesBeforeRead(Connection con, Object lob) {
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if (releaseResourcesAfterRead) {
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initOracleDriverClasses(con);
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try {
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/*
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if (!((BLOB)lob.isTemporary() {
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*/
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Method isTemporary = lob.getClass().getMethod("isTemporary");
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Boolean temporary = (Boolean) isTemporary.invoke(lob);
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if (!temporary) {
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/*
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((BLOB)lob).open(BLOB.MODE_READONLY);
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*/
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Method open = lob.getClass().getMethod("open", int.class);
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open.invoke(lob, modeReadOnlyConstants.get(lob.getClass()));
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}
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}
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catch (InvocationTargetException ex) {
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logger.error("Could not open Oracle LOB", ex.getTargetException());
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}
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catch (Exception ex) {
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throw new DataAccessResourceFailureException("Could not open Oracle LOB", ex);
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}
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}
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}
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/**
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* Release any LOB resources after read is complete.
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*
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* <p>If <code>releaseResourcesAfterRead</code> property is set to <code>true</code>
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* then this implementation calls
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* <code>BLOB.close()</code> or <code>CLOB.close()</code>
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* on any non-temporary LOBs that are open or
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* <code>BLOB.freeTemporary()</code> or <code>CLOB.freeTemporary()</code>
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* on any temporary LOBs.
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*
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* <p>This method can be overridden by sublcasses if different behavior is desired.
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* @param con the connection to be usde for initilization
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* @param lob the LOB to initialize
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*/
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protected void releaseResourcesAfterRead(Connection con, Object lob) {
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if (releaseResourcesAfterRead) {
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initOracleDriverClasses(con);
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Boolean temporary = Boolean.FALSE;
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try {
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/*
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if (((BLOB)lob.isTemporary() {
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*/
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Method isTemporary = lob.getClass().getMethod("isTemporary");
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temporary = (Boolean) isTemporary.invoke(lob);
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if (temporary) {
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/*
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((BLOB)lob).freeTemporary();
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*/
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Method freeTemporary = lob.getClass().getMethod("freeTemporary");
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freeTemporary.invoke(lob);
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}
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else {
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/*
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if (((BLOB)lob.isOpen() {
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*/
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Method isOpen = lob.getClass().getMethod("isOpen");
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Boolean open = (Boolean) isOpen.invoke(lob);
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if (open) {
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/*
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((BLOB)lob).close();
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*/
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Method close = lob.getClass().getMethod("close");
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close.invoke(lob);
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}
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}
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}
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catch (InvocationTargetException ex) {
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if (temporary) {
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logger.error("Could not free Oracle LOB", ex.getTargetException());
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}
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else {
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logger.error("Could not close Oracle LOB", ex.getTargetException());
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}
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}
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catch (Exception ex) {
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if (temporary) {
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throw new DataAccessResourceFailureException("Could not free Oracle LOB", ex);
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}
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else {
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throw new DataAccessResourceFailureException("Could not close Oracle LOB", ex);
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}
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}
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}
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}
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/**
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* LobCreator implementation for Oracle databases.
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