java.lang.Object
- org.springframework.jdbc.datasource.DelegatingDataSource
- - org.springframework.jdbc.datasource.TransactionAwareDataSourceProxy

All Implemented Interfaces:
Wrapper, CommonDataSource, DataSource, InitializingBean
```
public class TransactionAwareDataSourceProxy
extends DelegatingDataSource
```
Proxy for a target JDBC DataSource, adding awareness of Spring-managed transactions. Similar to a transactional JNDI DataSource as provided by a Java EE server.
Data access code that should remain unaware of Spring's data access support can work with this proxy to seamlessly participate in Spring-managed transactions. Note that the transaction manager, for example DataSourceTransactionManager, still needs to work with the underlying DataSource, not with this proxy.
Make sure that TransactionAwareDataSourceProxy is the outermost DataSource of a chain of DataSource proxies/adapters. TransactionAwareDataSourceProxy can delegate either directly to the target connection pool or to some intermediary proxy/adapter like LazyConnectionDataSourceProxy or UserCredentialsDataSourceAdapter.
Delegates to DataSourceUtils for automatically participating in thread-bound transactions, for example managed by DataSourceTransactionManager. getConnection calls and close calls on returned Connections will behave properly within a transaction, i.e. always operate on the transactional Connection. If not within a transaction, normal DataSource behavior applies.
This proxy allows data access code to work with the plain JDBC API and still participate in Spring-managed transactions, similar to JDBC code in a Java EE/JTA environment. However, if possible, use Spring's DataSourceUtils, JdbcTemplate or JDBC operation objects to get transaction participation even without a proxy for the target DataSource, avoiding the need to define such a proxy in the first place.
As a further effect, using a transaction-aware DataSource will apply remaining transaction timeouts to all created JDBC (Prepared/Callable)Statement. This means that all operations performed through standard JDBC will automatically participate in Spring-managed transaction timeouts.
NOTE: This DataSource proxy needs to return wrapped Connections (which implement the ConnectionProxy interface) in order to handle close calls properly. Therefore, the returned Connections cannot be cast to a native JDBC Connection type such as OracleConnection or to a connection pool implementation type. Use a corresponding NativeJdbcExtractor or JDBC 4's Wrapper.unwrap(java.lang.Class<T>) to retrieve the native JDBC Connection.
Since:
1.1
Author:
Juergen Hoeller
See Also:
DataSource.getConnection(), Connection.close(), DataSourceUtils.doGetConnection(javax.sql.DataSource), DataSourceUtils.applyTransactionTimeout(java.sql.Statement, javax.sql.DataSource), DataSourceUtils.doReleaseConnection(java.sql.Connection, javax.sql.DataSource)

Constructor Summary

Constructors
Constructor	Description
`TransactionAwareDataSourceProxy()`	Create a new TransactionAwareDataSourceProxy.
`TransactionAwareDataSourceProxy(DataSource targetDataSource)`	Create a new TransactionAwareDataSourceProxy.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`Connection`	`getConnection()`	Delegates to DataSourceUtils for automatically participating in Spring-managed transactions.
`protected Connection`	`getTransactionAwareConnectionProxy(DataSource targetDataSource)`	Wraps the given Connection with a proxy that delegates every method call to it but delegates `close()` calls to DataSourceUtils.
`void`	`setReobtainTransactionalConnections(boolean reobtainTransactionalConnections)`	Specify whether to reobtain the target Connection for each operation performed within a transaction.
`protected boolean`	`shouldObtainFixedConnection(DataSource targetDataSource)`	Determine whether to obtain a fixed target Connection for the proxy or to reobtain the target Connection for each operation.

Methods inherited from class org.springframework.jdbc.datasource.DelegatingDataSource
afterPropertiesSet, getConnection, getLoginTimeout, getLogWriter, getParentLogger, getTargetDataSource, isWrapperFor, setLoginTimeout, setLogWriter, setTargetDataSource, unwrap

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface javax.sql.CommonDataSource
createShardingKeyBuilder

Methods inherited from interface javax.sql.DataSource
createConnectionBuilder

- Constructor Detail
  - TransactionAwareDataSourceProxy
```
public TransactionAwareDataSourceProxy()
```
    Create a new TransactionAwareDataSourceProxy.
    See Also:
    DelegatingDataSource.setTargetDataSource(javax.sql.DataSource)
  - TransactionAwareDataSourceProxy
```
public TransactionAwareDataSourceProxy(DataSource targetDataSource)
```
    Create a new TransactionAwareDataSourceProxy.
    Parameters:
    targetDataSource - the target DataSource
- Method Detail
  - setReobtainTransactionalConnections
```
public void setReobtainTransactionalConnections(boolean reobtainTransactionalConnections)
```
    Specify whether to reobtain the target Connection for each operation performed within a transaction.
    The default is "false". Specify "true" to reobtain transactional Connections for every call on the Connection proxy; this is advisable on JBoss if you hold on to a Connection handle across transaction boundaries.
    The effect of this setting is similar to the "hibernate.connection.release_mode" value "after_statement".
  - getConnection
```
public Connection getConnection()
                         throws SQLException
```
    Delegates to DataSourceUtils for automatically participating in Spring-managed transactions. Throws the original SQLException, if any.
    The returned Connection handle implements the ConnectionProxy interface, allowing to retrieve the underlying target Connection.
    Specified by:
    getConnection in interface DataSource
    Overrides:
    getConnection in class DelegatingDataSource
    Returns:
    a transactional Connection if any, a new one else
    Throws:
    SQLException
    See Also:
    DataSourceUtils.doGetConnection(javax.sql.DataSource), ConnectionProxy.getTargetConnection()
  - getTransactionAwareConnectionProxy
```
protected Connection getTransactionAwareConnectionProxy(DataSource targetDataSource)
```
    Wraps the given Connection with a proxy that delegates every method call to it but delegates close() calls to DataSourceUtils.
    Parameters:
    targetDataSource - the DataSource that the Connection came from
    Returns:
    the wrapped Connection
    See Also:
    Connection.close(), DataSourceUtils.doReleaseConnection(java.sql.Connection, javax.sql.DataSource)
  - shouldObtainFixedConnection
```
protected boolean shouldObtainFixedConnection(DataSource targetDataSource)
```
    Determine whether to obtain a fixed target Connection for the proxy or to reobtain the target Connection for each operation.
    The default implementation returns true for all standard cases. This can be overridden through the "reobtainTransactionalConnections" flag, which enforces a non-fixed target Connection within an active transaction. Note that non-transactional access will always use a fixed Connection.
    Parameters:
    targetDataSource - the target DataSource

Class TransactionAwareDataSourceProxy

Constructor Summary

Method Summary

Methods inherited from class org.springframework.jdbc.datasource.DelegatingDataSource

Methods inherited from class java.lang.Object

Methods inherited from interface javax.sql.CommonDataSource

Methods inherited from interface javax.sql.DataSource

Constructor Detail

TransactionAwareDataSourceProxy

TransactionAwareDataSourceProxy

Method Detail

setReobtainTransactionalConnections

getConnection

getTransactionAwareConnectionProxy

shouldObtainFixedConnection