1 Understand Transaction
? 1) Introduce Spring's transaction manager
? a? JDBC transactions?
???? <bean id="transactionManager" class="org.springframework.jdbc.
????? datasource.DataSourceTransactionManager">
???? <property name="dataSource">
???? <ref bean="dataSource"/>
???? </property>
???? </bean>
?? b Hibernate transactions
???? <bean id="transactionManager" class="org.springframework.
?????? orm.hibernate.HibernateTransactionManager">
???? <property name="sessionFactory">
???? <ref bean="sessionFactory"/>
???? </property>
???? </bean>
2 Programing transaction in Spring
?? One approach to adding transaction to your code is to programmly add transactional boundary using transiationTemplate class.
?? Programming is good when you want complete control over transactional boundary.but you have to use spring specific class.In most case ,your tansactional needs will not require such precise control over transactional boundaries.That is why you will typically choolse to declare transaction support
? public void enrollStudentInCourse() {
??? transactionTemplate.execute(
??? new TransactionCallback() {
????? public Object doInTransaction(TransactionStatus ts) {
??????? try {
????????? // do stuff?? Runs within doInTransaction()
??????? } catch (Exception e) {
????????? ts.setRollbackOnly(); //Calls setRollbackOnly() to roll Calls setRollbackOnly()???????????????????????????????? //to roll back
??????? }
????????? return null;?? //If successful, transaction is committed
????? }
??? }
?? );
?}
?<bean id="transactionTemplate" class="org.springframework.
?????? transaction.support.TransactionTemplate">
? <property name="transactionManager">
??? <ref bean="transactionManager"/>
? </property>
?</bean>
?<bean id="courseService"
??? class="com.springinaction.training.service.CourseServiceImpl">
?<property name=" transactionTemplate">
???? <ref bean=" transactionTemplate"/>
?? </property>
?</bean>
3 Declaring transactions
? Spring's support for declarative transaction management is implementedd through Spirng's? AOP framework.
? <bean id="courseService" class="org.springframework.transaction.
?????? interceptor.TransactionProxyFactoryBean">
? <property name="proxyInterfaces">
??? <list>
????? <value>
??????? com.springinaction.training.service.CourseService??
????? </value>
??? </list>
? </property>
? <property name="target">
?? <ref bean="courseServiceTarget"/>?? //Bean being proxied
? </property>
?<property name="transactionManager">
?? <ref bean="transactionManager"/>?? //Transaction manager
?</property>
?<property name="transactionAttributeSource">
?? <ref bean="attributeSource"/>?? //Transaction attribute source
?</property>
?</bean>
?1) Understanding transaction attributes
? In Spring transaction attribute is a description of how transaction policies should be
applied to a methods
?? a? Propagation behavior
??? Propagation behavior???????????????? What it means
??? PROPAGATION_MANDATORY??????????????? indicate that the method must run within a????????????????????????????????????????????????? transaction.If no transaction is in progress
???????????????????????????????????????? an exception will be thrown
??? PROPAGATION_NESTED
??? PROPAGATION_NEVER??????????????????? indicate that the method can not run withi a??????????????????????????????????????????????? transaction. if a transaction exist an exception??????????????????????????????????????????? will be thrown.
??? PROPAGATIOM_NOT_SUPPORT????????????? Indicates that the method should not run within a?????????????????????????????????????????? transaction. If an existing transaction is????????????????????????????????????????????????? in progress, it will be suspended for the
???????????????????????????????????????? duration of the method.
??? PROPAGATION_REQUIRED???????????????? indicate that the current method must run within a????????????????????????????????????????? transaction.if an existing transaction is in??????????????????????????????????????????????? progress,the ,method will run with the transaction
???????????????????????????????????????? otherwise a new transaction will be started
??? PROPAGATION_REQUIRENEW?????????????? indicates that the current must run within its own
???????????????????????????????????????? transaction.A new transaction is started and an???????????????????????????????????????????? existing transaction will be suspend
??? PROPAGATION_SUPPORT????????????????? indicate the current mehtod does not require a????????????????????????????????????????? transaction.but may run if on is already in progress?????
??? b Isolation levels?????
??? Isolation level??????????????????? What it means
??? ISOLATION_DEFAULT????????????????? Using the defaul isolation level of the underlying????????????????????????????????????????? database
??? ISOLATION_READ_UNCOMMITTED???????? Allows you read change that have not yet been commit
?????????????????????????????????????? May result in dirty read,phantom read,nonrepeatable???????????????????????????????????????? read
??? ISOLATION_READ_COMMITTED?????????? Allows reads from concurrent transactions that have
?????????????????????????????????????? bean committed.Dirty read are prevent.but platform????????????????????????????????????????? and norepeatable reads may still occur.
??? ISOLATIOM_REPEATABLE_READ????????? Multiple read the same field will yield the same??????????????????????????????????????????? result ,unless changed by the transaction?????????????????????????????????????????????????? itself.Dirty reads ,nonrepeatable are all prevented
?????????????????????????????????????? phantom may still occur
??? ISOLATION_SERIALIZABLE???????????? This fully ACID-compliant isolation level ensusme??????????????????????????????????????? that dirty read,unrepeatable read ,phantom read are??????????????????????????????????????? all prevented.And this is the most slowest isolation
?????????????????????????????????????? since it is typically accomplished by doing full??????????????????????????????????????? table lock on the tables in the transaction.
?? c Read-Only
?? If a transaction performs only read operation against the underlying datastore.when a transaction begin ,it only make sense to declare a transaction as read only on mehtods with
propagation behavior which start a new transaction.
?? Furthermore ,if you are Hibernate as persistence mechanism,declaring a transaction as read only will reult in Hibernate flush mode being set to FLUST_NEVER.this tell hibernate to avoid synchroniztion of objects with database.
?? d Transaction timeout
?? Suppose that your transaction becomes unexpectedly long-running transaction.Because transaction may invole locks on the underlying database.Instead of waiting it out ,you can delcare a transaction to automaitically roll back.
?? because timeout clock begin ticking when a transaction start. it only make sense to declare a transaction timeout on methods with propagation behavior that start a new transaction.
? 2) Declaring a simple transaction policy
?? <bean id="myTransactionAttribute"
??? class="org.springframework.transaction.interceptor.
??????????? DefaultTransactionAttribute">
? <property name="propagationBehaviorName">
??? <value>PROPAGATION_REQUIRES_NEW</value>
? </property>
? <property name="isolationLevelName">
??? <value>ISOLATION_REPEATABLE_READ</value>
? </property>
?</bean>
?<bean id="transactionAttributeSource"
??? class="org.springframework.transaction.interceptor.
??????????? MatchAlwaysTransactionAttributeSource">
? <property name="transactionAttribute">
??? <ref bean="myTransactionAttribute"/>
? </property>
?</bean>
4 Declaring transactions by method name
? 1) Using NameMatchTransactionAttributeSource
? The properties property of NameMatchTransactionAttributeSource maps mehtod to a transaction property descriptor. the property descriptor takes the following form:
? Propagation,isolation,readOnly,-Exception,+Exception
?
? <bean id="transactionAttributeSource"
??? class="org.springframework.transaction.interceptor.
??????????? NameMatchTransactionAttributeSource">
? <property name="properties">
??? <props>
????? <prop key="enrollStudentInCourse">
????????? PROPAGATION_REQUIRES_NEW
????? </prop>
??? </props>
? </property>
?</bean>
?2) Specifying the transaction Isolation level
? <bean id="transactionAttributeSource"
??? class="org.springframework.transaction.interceptor.
??????????? NameMatchTransactionAttributeSource">
???? <property name="properties">
??? <props>
????? <prop key="enrollStudentInCourse">
??????? PROPAGATION_REQUIRES_NEW,ISOLATION_REPEATABLE_READ
????? </prop>
??? </props>
? </property>
?</bean>
?3) Using real-only transaction
? <bean id="transactionAttributeSource"
??? class="org.springframework.transaction.interceptor.
??????????? NameMatchTransactionAttributeSource">
? <property name="properties">
??? <props>
????? <prop key="getCompletedCourses">
??????? PROPAGATION_REQUIRED,ISOLATION_REPEATABLE_READ,readOnly
????? </prop>
??? </props>
? </property>
</bean>
?4)Specifying? rollback rules
? You can sepcify that a transaction be rollback on specify checked exception
? <bean id="transactionAttributeSource"
??? class="org.springframework.transaction.interceptor.
??????????? NameMatchTransactionAttributeSource">
? <property name="properties">
??? <props>
????? <prop key="enrollStudentInCourse">
??????? PROPAGATION_REQUIRES_NEW,ISOLATION_REPEATABLE_READ,
??????? -CourseException
??????? </prop>
???? </props>
??? </property>
? </bean>
? Exception can be marked as negative(-) or postive(+)
? Negative exception will trigger the roll back if the exception (or sublclass of it) is thrown.Postive exception on the other hand indicate that the transacton should be commit
even if the exception is thrown
?5)Using wildcard matches
?<bean id="transactionAttributeSource"
??? class="org.springframework.transaction.interceptor.
??????????? NameMatchTransactionAttributeSource">
? <property name="properties">
??? <props>
????? <prop key="get*">
??????? PROPAGATION_SUPPORTS
????? </prop>
??? </props>
? </property>
</bean>
?6 Short-cut name match transaction
?<bean id="courseService" class="org.springframework.transaction.
?????? interceptor.TransactionProxyFactoryBean">
?? <property name="transactionProperties">
??? <props>
????? <prop key="enrollStudentInCourse">
??????? PROPAGATION_REQUIRES_NEW
????? </prop>
??? </props>
?? </property>
?</bean>