Spring Basics
Bean lifecycle methods
There are three options for controlling bean lifecycle behavior: custom init() and destroy() methods; the @PostConstruct and @PreDestroy annotations and the
InitializingBean and DisposableBean callback interfaces.
Explain Bean lifecycle in Spring framework
The spring container finds the beans definition from the XML file and instantiates the bean.
Using the dependency injection, spring populates all of the properties as specified in the bean definition.
If the bean implements the BeanNameAware interface, the factory calls setBeanName() passing the bean's ID.
If the bean implements the BeanFactoryAware interface, the factory calls setBeanFactory(), passing an instance of itself.
If there are any BeanPostProcessors associated with the bean, their post- ProcessBeforeInitialization() methods will be called.
If an init-method is specified for the bean, it will be called.
Finally, if there are any BeanPostProcessors associated with the bean, their postProcessAfterInitialization() methods will be called.
What are different types of Autowire types?
byName,byType,constructor,autodetect
AutowireCapableBeanFactory{AUTOWIRE_NO, AUTOWIRE_BY_NAME, AUTOWIRE_BY_TYPE, AUTOWIRE_CONSTRUCTOR, AUTOWIRE_AUTODETECT(@Deprecated)}
What are the different advice types in spring?
Around: Intercepts the calls to the target method
Before: This is called before the target method is invoked
After: This is called after the target method is returned
Throws: This is called when the target method throws and exception
Transaction
Defined in TransactionDefinition:
IsolationLevel
ISOLATION_DEFAULT
ISOLATION_READ_UNCOMMITTED
ISOLATION_READ_COMMITTED
ISOLATION_REPEATABLE_READ
ISOLATION_SERIALIZABLE
Propagation behavior(7 types)
PROPAGATION_REQUIRED
PROPAGATION_SUPPORTS
PROPAGATION_MANDATORY
Support a current transaction; throw an exception if no current transaction exists.
PROPAGATION_REQUIRES_NEW
Create a new transaction, suspending the current transaction if one exists
PROPAGATION_NOT_SUPPORTED
Do not support a current transaction; rather always execute non-transactionally.
PROPAGATION_NEVER
Do not support a current transaction; throw an exception if a current transaction exists.
PROPAGATION_NESTED = 6
Execute within a nested transaction if a current transaction exists, behave like {@link #PROPAGATION_REQUIRED} else.
isReadOnly
Declaratively rolling back a transaction
The recommended way to to roll back a transaction is to throw an Exception.
Be default, Any RuntimeException(unchecked exception) triggers rollback, and any checked Exception does not.
You can configure exactly which Exception types mark a transaction for rollback, including checked exceptions.
Programmatically rolling back a transaction
TransactionAspectSupport.currentTransactionStatus().setRollbackOnly();
Default settings
• Propagation setting is REQUIRED.
• Isolation level is DEFAULT.
• Transaction is read/write.
• Any RuntimeException triggers rollback, and any checked Exception does not.
First configure dataSource and transactionManager in Spring configuration file.
Declarative Transaction through XML
This is the most common as it is non-intrusive, and has the least impact on application code.
expression="execution(* com.mydomain.spring.transaction.declarative.xml.XmlTransactionTestService.*(..))" />
The
Declarative via Annotations
Configure the transaction attributes via annotations in the Java source file.
@Transactional(propagation, isolation, timeout, readOnly, rollbackFor, noRollbackFor)
Programmatic - TransactionTemplate
final TransactionTemplate tt = new TransactionTemplate(transactionManager);
tt.setReadOnly(true);
tt.execute(new TransactionCallbackWithoutResult() {
public void doInTransactionWithoutResult(TransactionStatus status) {
// do stuff
status.setRollbackOnly();
}
});
Spring Event Framework
ApplicationEvent, ApplicationListener, ApplicationEventPublisher.publishEvent(event)
If a Spring bean implements the ApplicationListener, every time an ApplicationEvent gets published to the ApplicationContext, that bean is notified. This is the standard Observer design pattern, we can use it in our Spring-enabled project.
public class EmailService implements ApplicationEventPublisherAware
ApplicationEventPublisher.publishEvent(event);
Hidden features of Spring framework
StringUtilsremoveDuplicateStrings, hasText, capitalize, uncapitalize, getFilenameExtension, stripFilenameExtension
FileCopyUtils.copy
Resources
