org.springframework.batch.item.database
Class ExtendedConnectionDataSourceProxy

java.lang.Object
  org.springframework.batch.item.database.ExtendedConnectionDataSourceProxy

All Implemented Interfaces:

Wrapper, CommonDataSource, DataSource, InitializingBean, SmartDataSource

public class ExtendedConnectionDataSourceProxy
extends Object
implements SmartDataSource, InitializingBean

Implementation of SmartDataSource that is capable of keeping a single JDBC Connection which is NOT closed after each use even if Connection.close() is called. The connection can be kept open over multiple transactions when used together with any of Spring's PlatformTransactionManager implementations.

Loosely based on the SingleConnectionDataSource implementation in Spring Core. Intended to be used with the JdbcCursorItemReader to provide a connection that remains open across transaction boundaries, It remains open for the life of the cursor, and can be shared with the main transaction of the rest of the step processing.

Once close suppression has been turned on for a connection, it will be returned for the first getConnection() call. Any subsequent calls to getConnection() will retrieve a new connection from the wrapped DataSource until the DataSourceUtils queries whether the connection should be closed or not by calling shouldClose(Connection) for the close-suppressed Connection. At that point the cycle starts over again, and the next getConnection() call will have the Connection that is being close-suppressed returned. This allows the use of the close-suppressed Connection to be the main Connection for an extended data access process. The close suppression is turned off by calling stopCloseSuppression(Connection).

This class is not multi-threading capable.

The connection returned will be a close-suppressing proxy instead of the physical Connection. Be aware that you will not be able to cast this to a native OracleConnection or the like anymore; you need to use a NativeJdbcExtractor.

Since:

2.0

Author:

Thomas Risberg

See Also:

getConnection(), Connection.close(), DataSourceUtils.releaseConnection(java.sql.Connection, javax.sql.DataSource), NativeJdbcExtractor

Constructor Summary

ExtendedConnectionDataSourceProxy()
No arg constructor for use when configured using JavaBean style.

ExtendedConnectionDataSourceProxy(DataSource dataSource)
Constructor that takes as a parameter with the {&link DataSource} to be wrapped.

Method Summary

void	afterPropertiesSet()
protected Connection	getCloseSuppressingConnectionProxy(Connection target) Wrap the given Connection with a proxy that delegates every method call to it but suppresses close calls.
Connection	getConnection()
Connection	getConnection(String username, String password)
int	getLoginTimeout()
PrintWriter	getLogWriter()
Logger	getParentLogger() Added due to JDK 7 compatibility, sadly a proper implementation that would throw SqlFeatureNotSupportedException is not possible in Java 5 (the class was added in Java 6).
boolean	isCloseSuppressionActive(Connection connection) Return the status of close suppression being activated for a given Connection
boolean	isWrapperFor(Class<?> iface) Performs only a 'shallow' non-recursive check of self's and delegate's class to retain Java 5 compatibility.
void	setDataSource(DataSource dataSource) Setter for the {&link DataSource} that is to be wrapped.
void	setLoginTimeout(int seconds)
void	setLogWriter(PrintWriter out)
boolean	shouldClose(Connection connection)
void	startCloseSuppression(Connection connection)
void	stopCloseSuppression(Connection connection)
<T> T	unwrap(Class<T> iface) Returns either self or delegate (in this order) if one of them can be cast to supplied parameter class.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ExtendedConnectionDataSourceProxy

public ExtendedConnectionDataSourceProxy()

No arg constructor for use when configured using JavaBean style.

ExtendedConnectionDataSourceProxy

public ExtendedConnectionDataSourceProxy(DataSource dataSource)

Constructor that takes as a parameter with the {&link DataSource} to be wrapped.

Method Detail

setDataSource

public void setDataSource(DataSource dataSource)

Setter for the {&link DataSource} that is to be wrapped.

Parameters:

dataSource - the DataSource

shouldClose

public boolean shouldClose(Connection connection)

Specified by:

shouldClose in interface SmartDataSource

See Also:

SmartDataSource

isCloseSuppressionActive

public boolean isCloseSuppressionActive(Connection connection)

Return the status of close suppression being activated for a given Connection

Parameters:

connection - the Connection that the close suppression status is requested for

Returns:

true or false

startCloseSuppression

public void startCloseSuppression(Connection connection)

Parameters:

connection - the Connection that close suppression is requested for

stopCloseSuppression

public void stopCloseSuppression(Connection connection)

Parameters:

connection - the Connection that close suppression should be turned off for

getConnection

public Connection getConnection()
                         throws SQLException

Specified by:

getConnection in interface DataSource

Throws:

SQLException

getConnection

public Connection getConnection(String username,
                                String password)
                         throws SQLException

Specified by:

getConnection in interface DataSource

Throws:

SQLException

getLogWriter

public PrintWriter getLogWriter()
                         throws SQLException

Specified by:

getLogWriter in interface CommonDataSource

Throws:

SQLException

getLoginTimeout

public int getLoginTimeout()
                    throws SQLException

Specified by:

getLoginTimeout in interface CommonDataSource

Throws:

SQLException

setLogWriter

public void setLogWriter(PrintWriter out)
                  throws SQLException

Specified by:

setLogWriter in interface CommonDataSource

Throws:

SQLException

setLoginTimeout

public void setLoginTimeout(int seconds)
                     throws SQLException

Specified by:

setLoginTimeout in interface CommonDataSource

Throws:

SQLException

getCloseSuppressingConnectionProxy

protected Connection getCloseSuppressingConnectionProxy(Connection target)

Wrap the given Connection with a proxy that delegates every method call to it but suppresses close calls.

Parameters:

target - the original Connection to wrap

Returns:

the wrapped Connection

isWrapperFor

public boolean isWrapperFor(Class<?> iface)
                     throws SQLException

Performs only a 'shallow' non-recursive check of self's and delegate's class to retain Java 5 compatibility.

Specified by:

isWrapperFor in interface Wrapper

Throws:

SQLException

unwrap

public <T> T unwrap(Class<T> iface)
         throws SQLException

Returns either self or delegate (in this order) if one of them can be cast to supplied parameter class. Does *not* support recursive unwrapping of the delegate to retain Java 5 compatibility.

Specified by:

unwrap in interface Wrapper

Throws:

SQLException

afterPropertiesSet

public void afterPropertiesSet()
                        throws Exception

Specified by:

afterPropertiesSet in interface InitializingBean

Throws:

Exception

getParentLogger

public Logger getParentLogger()

Added due to JDK 7 compatibility, sadly a proper implementation that would throw SqlFeatureNotSupportedException is not possible in Java 5 (the class was added in Java 6).