public class IsolationLevelDataSourceRouter extends AbstractRoutingDataSource
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>
AbstractRoutingDataSource.setTargetDataSources(java.util.Map<java.lang.Object, java.lang.Object>)
,
AbstractRoutingDataSource.setDefaultTargetDataSource(java.lang.Object)
,
TransactionDefinition.ISOLATION_READ_UNCOMMITTED
,
TransactionDefinition.ISOLATION_READ_COMMITTED
,
TransactionDefinition.ISOLATION_REPEATABLE_READ
,
TransactionDefinition.ISOLATION_SERIALIZABLE
,
JtaTransactionManager
Modifier and Type | Field and Description |
---|---|
private static Constants |
constants
Constants instance for TransactionDefinition
|
logger
Constructor and Description |
---|
IsolationLevelDataSourceRouter() |
Modifier and Type | Method and Description |
---|---|
protected java.lang.Object |
determineCurrentLookupKey()
Determine the current lookup key.
|
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 . |
afterPropertiesSet, determineTargetDataSource, getConnection, getConnection, resolveSpecifiedDataSource, setDataSourceLookup, setDefaultTargetDataSource, setLenientFallback, setTargetDataSources
getLoginTimeout, getLogWriter, getParentLogger, isWrapperFor, setLoginTimeout, setLogWriter, unwrap
private static final Constants constants
protected java.lang.Object resolveSpecifiedLookupKey(java.lang.Object lookupKey)
TransactionDefinition interface
.resolveSpecifiedLookupKey
in class AbstractRoutingDataSource
lookupKey
- the lookup key object as specified by the userprotected java.lang.Object determineCurrentLookupKey()
AbstractRoutingDataSource
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.
determineCurrentLookupKey
in class AbstractRoutingDataSource