org.springframework.jdbc.datasource.lookup
Class IsolationLevelDataSourceRouter
java.lang.Object
org.springframework.jdbc.datasource.AbstractDataSource
org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource
org.springframework.jdbc.datasource.lookup.IsolationLevelDataSourceRouter
- All Implemented Interfaces:
- java.sql.Wrapper, javax.sql.CommonDataSource, javax.sql.DataSource, InitializingBean
public class IsolationLevelDataSourceRouter
- extends AbstractRoutingDataSource
DataSource that routes to one of various target DataSources based on the
current transaction isolation level. The target DataSources need to be
configured with the isolation level name as key, as defined on the
TransactionDefinition interface
.
This is particularly useful in combination with JTA transaction management
(typically through Spring's JtaTransactionManager
).
Standard JTA does not support transaction-specific isolation levels. Some JTA
providers support isolation levels as a vendor-specific extension (e.g. WebLogic),
which is the preferred way of addressing this. As alternative (e.g. on WebSphere),
the target database can be represented through multiple JNDI DataSources, each
configured with a different isolation level (for the entire DataSource).
The present DataSource router allows to transparently switch to the
appropriate DataSource based on the current transaction's isolation level.
The configuration can for example look like this, assuming that the target
DataSources are defined as individual Spring beans with names
"myRepeatableReadDataSource", "mySerializableDataSource" and "myDefaultDataSource":
<bean id="dataSourceRouter" class="org.springframework.jdbc.datasource.lookup.IsolationLevelDataSourceRouter">
<property name="targetDataSources">
<map>
<entry key="ISOLATION_REPEATABLE_READ" value-ref="myRepeatableReadDataSource"/>
<entry key="ISOLATION_SERIALIZABLE" value-ref="mySerializableDataSource"/>
</map>
</property>
<property name="defaultTargetDataSource" ref="myDefaultDataSource"/>
</bean>
Alternatively, the keyed values can also be data source names, to be resolved
through a DataSourceLookup
: by default, JNDI
names for a standard JNDI lookup. This allows for a single concise definition
without the need for separate DataSource bean definitions.
<bean id="dataSourceRouter" class="org.springframework.jdbc.datasource.lookup.IsolationLevelDataSourceRouter">
<property name="targetDataSources">
<map>
<entry key="ISOLATION_REPEATABLE_READ" value="java:comp/env/jdbc/myrrds"/>
<entry key="ISOLATION_SERIALIZABLE" value="java:comp/env/jdbc/myserds"/>
</map>
</property>
<property name="defaultTargetDataSource" value="java:comp/env/jdbc/mydefds"/>
</bean>
Note: If you are using this router in combination with Spring's
JtaTransactionManager
,
don't forget to switch the "allowCustomIsolationLevels" flag to "true".
(By default, JtaTransactionManager will only accept a default isolation level
because of the lack of isolation level support in standard JTA itself.)
<bean id="transactionManager" class="org.springframework.transaction.jta.JtaTransactionManager">
<property name="allowCustomIsolationLevels" value="true"/>
</bean>
- Since:
- 2.0.1
- Author:
- Juergen Hoeller
- See Also:
AbstractRoutingDataSource.setTargetDataSources(java.util.Map)
,
AbstractRoutingDataSource.setDefaultTargetDataSource(java.lang.Object)
,
TransactionDefinition.ISOLATION_READ_UNCOMMITTED
,
TransactionDefinition.ISOLATION_READ_COMMITTED
,
TransactionDefinition.ISOLATION_REPEATABLE_READ
,
TransactionDefinition.ISOLATION_SERIALIZABLE
,
JtaTransactionManager
Field Summary |
private static Constants |
constants
Constants instance for TransactionDefinition |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
constants
private static final Constants constants
- Constants instance for TransactionDefinition
IsolationLevelDataSourceRouter
public IsolationLevelDataSourceRouter()
resolveSpecifiedLookupKey
protected java.lang.Object resolveSpecifiedLookupKey(java.lang.Object lookupKey)
- Supports Integer values for the isolation level constants
as well as isolation level names as defined on the
TransactionDefinition interface
.
- Overrides:
resolveSpecifiedLookupKey
in class AbstractRoutingDataSource
- Parameters:
lookupKey
- the lookup key object as specified by the user
- Returns:
- the lookup key as needed for matching
determineCurrentLookupKey
protected java.lang.Object determineCurrentLookupKey()
- Description copied from class:
AbstractRoutingDataSource
- Determine the current lookup key. This will typically be
implemented to check a thread-bound transaction context.
Allows for arbitrary keys. The returned key needs
to match the stored lookup key type, as resolved by the
AbstractRoutingDataSource.resolveSpecifiedLookupKey(java.lang.Object)
method.
- Specified by:
determineCurrentLookupKey
in class AbstractRoutingDataSource