What is Spring ?
Spring is an open source framework created to address the complexity of enterprise application development. One of the chief advantages of the Spring framework is its layered architecture, which allows you to be selective about which of its components you use while also providing a cohesive framework for J2EE application development.
What are features of Spring ?
Lightweight:
spring is lightweight when it comes to size and transparency. The basic version of spring framework is around 1MB. And the processing overhead is also very negligible.
Inversion of control (IOC):
Loose coupling is achieved in spring using the technique Inversion of Control. The objects give their dependencies instead of creating or looking for dependent objects.
Aspect oriented (AOP):
Spring supports Aspect oriented programming and enables cohesive development by separating application business logic from system services.
Container:
Spring contains and manages the life cycle and configuration of application objects.
MVC Framework:
Spring comes with MVC web application framework, built on core Spring functionality. This framework is highly configurable via strategy interfaces, and accommodates multiple view technologies like JSP, Velocity, Tiles, iText, and POI. But other frameworks can be easily used instead of Spring MVC Framework.
Transaction Management:
Spring framework provides a generic abstraction layer for transaction management. This allowing the developer to add the pluggable transaction managers, and making it easy to demarcate transactions without dealing with low-level issues. Spring's transaction support is not tied to J2EE environments and it can be also used in container less environments.
JDBC Exception Handling:
The JDBC abstraction layer of the Spring offers a meaningful exception hierarchy, which simplifies the error handling strategy. Integration with Hibernate, JDO, and iBATIS: Spring provides best Integration services with Hibernate, JDO and iBATIS
contexts for Web-based applications. As a result, the Spring framework supports integration with Jakarta Struts. The Web module also eases the tasks of handling multi-part requests and binding request parameters to domain objects.
.How to read the spring-config.xml?
By
using Application Context interface.its implementation class is used to
read spring-confg.xml file
ApplicationContext context =new
ClassPathxmlApplication (“spring-config.xml”);
Advantages of spring?
1.
spring is open source and light weight framework
2.
singleton is not required to implement
3.
Transaction logic is just configuration
4.Exception
Handling is very simple
5.It
will simplifiey JDBC coding
6It
will simplifiey ORM coding
7.Resource closeing is not
required while working with spring
8.It will simplify RMO coding and EJB
How many ways to archive dependency injection?
1.
Constructer dependency injection
2.
Setter dependency injection
3.intrerface
injection
--àDependencies are provided through the constructer of the
component
EX. Public
class ContructerInjection {---àservice
Private
dependency dep;---àDao
Public
Constructer Injection(Dependency dep){
this.dep=dep;
}
}
---àDependencies are provided through the java bean style
setter() method of the component.It is more popular then constructer injection
EX:
public
class SetterInjection{---àservice
Private
dependency dep;---àDao
Public
void setMyDependancy(Dependancy dep){
This.dep=dep;
}
}
àIn
interface injection we have have to implement special interfaces
Spring container?
Spring container works based on following
1. Bean Factory (interface)
2. Application Context (interface)
3. WebApplicationContext (interface)
BeanFactory
BeanFactory is a lightweight container it
loads bean definitions and manages your
beans and manage a singleton or prototype defined bean
The implementation classes are
ClassPathResource: In this no need to
complete file path
BeanFactory factory =new XmlBeanFactory (new
ClassPathResource (“applicationContext.xml”);
2
FileSystemResource
BeanFactory factory =new XmlBeanFactory (new
FileSystemResource (“C:..\appicationContext.xml”);
Note:
1. spring doesn’t create the single object
while reading the spring-config.xml>It creates the single object when we
call first time getBean (-,-)
2. BeanFactory doesn’t support I18 and Event Handling
Application
Context
Application context provides all the features
of BeanFactory and some additional features like I18 concepts
and Event Handling]
AC provides generic way to load file
resources such as images Implementation classless for AC
FileSystemApplicationContext:It is like above
file system Resource. This class accepts only total path of file
syntax
BeanFactory factory =new
FileSystemXmlApplication (new FileSystemResource
(“C:..\appicationContext.xml”);
2.
ClassPathXmlApplicationContext:It is like above class path Resource.It loads
configuration from classpath(using classLoder concept)
syntax
BeanFactory factory =new
ClassPathXmlApplicationContext (new ClassPathResource
(“applicationContext.xml”);
Note
While reading the configuration file it
creates the singleton objects.
What is auto wiring?
In spring we have set the dependencies we
have to approaches, constructer injection and setter injection. instead them we have to inject the dependencies
automatically we use concept called auto
wiring
1.In constructer injection just use the
following configuration
<autowire=”constructer”>------------àit will set all the dependencies
2.In setter injection just use the following
configuration tag
<autowire =”byname”> -------------à it will set all the dependencies
-àif we want to assign values with then we have to use
manual(like constructer and setter injections)
àif
we have less dependencies then we can prefer auto wiring
What
is parent attribute?
In java inheritance is achieved using extends
keyword. in spring we can get one bean
definition details into another bean we use this parent attribute
What are main features of spring?
The main features of spring are
1.IOC
or Dependency injection
2.Loosely
coupled
What is IOC or Dependency injection?
Framework container runtime environment is dynamically assigning dependent values to recourses of
application then it is called Dependency injection or or IOC
Ex: The way ActionServlet writes the form data to FormBean class object
comes under dependency injection
What is spring bean?
Any predefined or user defined java classes are called spring bean
Spring support POJO classes or not?
Spring supports pojo classess.pojo class is
nothing but a class which is not
extending any other class or technology
Procedure to
set up first spring application?
1.create a work space for spring application
2.create the java project
3.add the spring libraries to project by
selecting add spring capabilities in
myeclipse.in Eclipse ide following way
ProjectàpropertiesàjavaBuildPathàAdd librayàuser Libraryànewàcreate
a folder lib(spring)àadd
jarsàthen add all spring jars
For developing a spring App u have to create
the following classes?
1.spring bean class
2.spring bean configuration class
3.client app to get the bean class object
Differentiate between BeanFactory and
ApplicationContext in spring.
- With ApplicationContext more than one
config files are possible while only one config file or .xml file is possible
with BeanFactory.
- ApplicationContext publishes events to beans that are registered as listeners
while BeanFactory doesn't support this
- ApplicationContext support internationalization messages, application
life-cycle events, validation and many enterprise services like JNDI access,
EJB integration, remoting etc. while BeanFactory doesn't support any of these.
What is the difference between singleton and
prototype bean?
Mainly it is the scope of a beans which
defines their existence on the application
- Singleton: It means single bean definition to a single object instance per
Spring IOC container.
- Prototype: It means a single bean definition to any number of object
instances.
How do
beans become 'singleton' or prototype?
- There exists an attribute in bean tag,
called 'singleton’.
- If it is marked 'true', the bean becomes singleton.
- If it is marked 'false', the bean becomes prototype.
What
type of transaction Management Spring support?
Spring supports two types of transaction management:
1. Programmatic transaction management
2. Declarative transaction management.
When do you use
programmatic and declarative transaction management ?
- Programmatic transaction management is used
preferably when you have a small number of transactional operations.
- Incase of large number of transactional operations it is better to use
declarative transaction management.
What is IOC?
- IOC stands for Inversion of Control
pattern.
- It is also called as dependency injection.
- This concept says that you do not create your objects but describe how they
should be created.
- Similarly, you do not directly connect your components and services together
in code but describe which services are needed by which components in a
configuration file.
- A container then hooks them all up.
What are the benefits of IOC?
The main benefits of IOC or dependency
injection are:
a.) It minimizes the amount of code in your application.
b.) It makes your application easy to test as it doesn't require any singletons
or JNDI lookup mechanisms in your unit test cases.
c.) Loose coupling is promoted with minimal effort and least intrusive
mechanism.
d.) IOC containers support eager instantiation and lazy loading of services
.
What is Bean Wiring ?
Bean wiring means creating associations
between application components i.e. beans within the spring container.
What
is IOC (or Dependency Injection)?
The basic concept of the Inversion of Control pattern (also known as dependency
injection) is that you do not create your objects but describe how they should
be created. You don't directly connect your components and services together in
code but describe which services are needed by which components in a
configuration file. A container (in the case of the Spring framework, the IOC
container) is then responsible for hooking it all up.
i.e., Applying IoC, objects are given their dependencies at creation time by
some external entity that coordinates each object in the system. That is,
dependencies are injected into objects. So, IoC means an inversion of
responsibility with regard to how an object obtains references to collaborating
objects.
What
are the different types of IOC (dependency injection) ?
There are three types of dependency injection:
- Constructor Injection (e.g. Pico container, Spring etc): Dependencies
are provided as constructor parameters.
- Setter Injection (e.g. Spring): Dependencies are assigned through
JavaBeans properties (ex: setter methods).
- Interface Injection (e.g. Avalon): Injection is done through an interface.
Note:
Spring supports only Constructor and Setter Injection
What
are the benefits of IOC (Dependency Injection)?
Benefits of IOC (Dependency Injection) are as follows:
- Minimizes the amount of code in
your application.
- Make your application more
testable by not requiring any singletons or JNDI lookup mechanisms in your
unit test cases.
- Loose coupling is promoted with
minimal effort and least intrusive mechanism
- IOC containers support eager
instantiation and lazy loading of services.
What
is web module?
This
module is built on the application context module, providing a context that is
appropriate for web-based applications. This module also contains support for
several web-oriented tasks such as transparently handling multipart requests
for file uploads and programmatic binding of request parameters to your
business objects. It also contains integration support with Jakarta
Struts.
What
are the types of Dependency Injection Spring supports?
Setter
Injection:
Setter-based DI is realized by calling setter methods on your beans after
invoking a no-argument constructor or no-argument static factory method to
instantiate your bean.
Constructor
Injection:
Constructor-based
DI is realized by invoking a constructor with a number of arguments, each
representing a collaborator.
What
is Bean Factory ?
A BeanFactory is like a factory class that contains a collection of beans. The
BeanFactory holds Bean Definitions of multiple beans within itself and then
instantiates the bean whenever asked for by clients.
- BeanFactory is able to create
associations between collaborating objects as they are instantiated. This
removes the burden of configuration from bean itself and the beans client.
- BeanFactory also takes part in
the life cycle of a bean, making calls to custom initialization and
destruction methods.
What
is Application Context?
A bean factory is fine to simple applications, but to take advantage of the
full power of the Spring framework, you may want to move up to Springs more
advanced container, the application context. On the surface, an application
context is same as a bean factory.Both load bean definitions, wire beans
together, and dispense beans upon request. But it also provides:
- A means for resolving text
messages, including support for internationalization.
- A generic way to load file
resources.
- Events to beans that are
registered as listeners.
What is the difference
between Bean Factory and Application Context ?
On the surface, an application context is same as a bean
factory. But application context offers much more..
- Application contexts provide a means for resolving text
messages, including support for i18n of those messages.
- Application contexts provide a generic way to load file
resources, such as images.
- Application contexts can publish events to beans that
are registered as listeners.
- Certain operations on the container or beans in the
container, which have to be handled in a programmatic fashion with a bean
factory, can be handled declaratively in an application context.
- ResourceLoader support: Spring’s Resource interface us
a flexible generic abstraction for handling low-level resources. An
application context itself is a ResourceLoader, Hence provides an
application with access to deployment-specific Resource instances.
- MessageSource support: The application context
implements MessageSource, an interface used to obtain localized messages,
with the actual implementation being pluggable
What are the common
implementations of the Application Context ?
The three commonly used implementation
of 'Application Context' are
- ClassPathXmlApplicationContext
: It Loads context definition
from an XML file located in the classpath, treating context definitions as
classpath resources. The application context is loaded from the
application's classpath by using the code .
ApplicationContext context = new
ClassPathXmlApplicationContext("bean.xml");
- FileSystemXmlApplicationContext
: It loads context definition
from an XML file in the filesystem. The application context is loaded from
the file system by using the code .
ApplicationContext context = new
FileSystemXmlApplicationContext("bean.xml");
- XmlWebApplicationContext
: It
loads context definition from an XML file contained within a web
application.
How is a typical spring
implementation look like ?
For a typical Spring Application
we need the following files:
- An interface that defines the functions.
- An Implementation that contains properties, its setter
and getter methods, functions etc.,
- Spring AOP (Aspect Oriented Programming)
- A XML file called Spring configuration file.
- Client program that uses the function.
What is the typical Bean life cycle in Spring
Bean Factory Container ?
Bean life cycle in Spring Bean Factory
Container is as follows:
- The spring container finds the bean’s 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 do you mean by Bean
wiring ?
The act of creating associations between application
components (beans) within the Spring container is reffered to as Bean wiring.
What do you mean by Auto
Wiring?
The Spring container is able to
autowire relationships between collaborating beans. This means that it is
possible to automatically let Spring resolve collaborators (other beans) for
your bean by inspecting the contents of the BeanFactory. The autowiring
functionality has five modes.
- no
- byName
- byType
- constructor
- autodirect
What is DelegatingVariableResolver?
Spring provides a custom
JavaServer Faces VariableResolver implementation that extends the standard Java
Server Faces managed beans mechanism which lets you use JSF and Spring
together. This variable resolver is called asDelegatingVariableResolver
How to integrate Java
Server Faces (JSF) with Spring?
JSF and Spring do share some of the
same features, most noticeably in the area of IOC services. By declaring JSF
managed-beans in the faces-config.xml configuration file, you allow the
FacesServlet to instantiate that bean at startup. Your JSF pages have access to
these beans and all of their properties.We can integrate JSF and Spring in two
ways:
- DelegatingVariableResolver: Spring comes with a JSF
variable resolver that lets you use JSF and Spring together.
<?xml version="1.0"
encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"
"http://www.springframework.org/dtd/spring-beans.dtd">
<faces-config>
<application>
<variable-resolver>
org.springframework.web.jsf.DelegatingVariableResolver
</variable-resolver>
</application>
</faces-config>
The DelegatingVariableResolver will first delegate value lookups to the default
resolver of the underlying JSF implementation, and then to Spring's 'business
context' WebApplicationContext. This allows one to easily inject dependencies
into one's JSF-managed beans.
- FacesContextUtils:custom VariableResolver works well
when mapping one's properties to beans in faces-config.xml, but at times
one may need to grab a bean explicitly. The FacesContextUtils class makes
this easy. It is similar to WebApplicationContextUtils, except that it
takes a FacesContext parameter rather than a ServletContext parameter.
ApplicationContext ctx =
FacesContextUtils.getWebApplicationContext(FacesContext.getCurrentInstance());
What is Java Server
Faces (JSF) - Spring integration mechanism?
Spring provides a custom JavaServer Faces
VariableResolver implementation that extends the standard JavaServer Faces
managed beans mechanism. When asked to resolve a variable name, the following
algorithm is performed:
- Does a bean with the specified name already exist in
some scope (request, session, application)? If so, return it
- Is there a standard JavaServer Faces managed bean
definition for this variable name? If so, invoke it in the usual way, and
return the bean that was created.
- Is there configuration information for this variable
name in the Spring WebApplicationContext for this application? If so, use
it to create and configure an instance, and return that instance to the
caller.
- If there is no managed bean or Spring definition for
this variable name, return null instead.
- BeanFactory also takes part in the life cycle of a
bean, making calls to custom initialization and destruction methods.
As a result of this algorithm, you can
transparently use either JavaServer Faces or Spring facilities to create beans
on demand.
What is Significance of
JSF- Spring integration ?
Spring - JSF integration is useful when an event handler
wishes to explicitly invoke the bean factory to create beans on demand, such as
a bean that encapsulates the business logic to be performed when a submit
button is pressed.
How to integrate your
Struts application with Spring?
To integrate your Struts application with Spring, we have
two options:
- Configure Spring to manage your Actions as beans, using
the ContextLoaderPlugin, and set their dependencies in a Spring context
file.
- Subclass Spring's ActionSupport classes and grab your
Spring-managed beans explicitly using a getWebApplicationContext() method.
What are Bean scopes in
Spring Framework ?
The Spring Framework supports exactly five
scopes (of which three are available only if you are using a web-aware
ApplicationContext). The scopes supported are listed below:
Scope
|
Description
|
singleton
|
Scopes a single bean definition to a single
object instance per Spring IoC container.
|
prototype
|
Scopes a single bean definition to any
number of object instances.
|
request
|
Scopes a single bean definition to the
lifecycle of a single HTTP request; that is each and every HTTP request will
have its own instance of a bean created off the back of a single bean
definition. Only valid in the context of a web-aware Spring ApplicationContext.
|
session
|
Scopes a single bean definition to the
lifecycle of a HTTP Session. Only valid in the context of a web-aware Spring
ApplicationContext.
|
global session
|
Scopes a single bean definition to the
lifecycle of a global HTTP Session. Typically only valid when used in a
portlet context. Only valid in the context of a web-aware Spring
ApplicationContext.
|
What are the types of the
transaction management Spring supports ?
Spring Framework supports:
- Programmatic transaction management.
- Declarative transaction management.
What are the benefits
of the Spring Framework transaction management ?
The Spring Framework provides a consistent
abstraction for transaction management that delivers the following benefits:
- Provides a consistent programming model across
different transaction APIs such as JTA, JDBC, Hibernate, JPA, and JDO.
- Supports declarative transaction management.
- Provides a simpler API for programmatic transaction
management than a number of complex transaction APIs such as JTA.
- Integrates very well with Spring's various data access
abstractions.
Why most users of the
Spring Framework choose declarative transaction management ?
Most users of the Spring Framework
choose declarative transaction management because it is the option with the
least impact on application code, and hence is most consistent with the ideals
of a non-invasive lightweight container.
What is SQLProvider ?
SQLProvider:
- Has
one method – getSql()
- Typically
implemented by PreparedStatementCreator implementers.
- Useful
for debugging.
What is RowCallbackHandler ?
The RowCallbackHandler interface extracts values
from each row of a ResultSet.
- Has
one method – processRow(ResultSet)
- Called
for each row in ResultSet.
- Typically
stateful.
Do I need any other SOAP framework to run
Spring Web Services?
You don't need any other SOAP framework to use Spring Web
services, though it can use
some of the features of Axis 1 and 2.
I get
NAMESPACE_ERR exceptions when using Spring-WS. What can I do about it?
If you get the following Exception:
NAMESPACE_ERR: An attempt is made to create or change an object in a way which
is incorrect with regard to namespaces.
Most often, this exception is related to an older version of Xalan being used.
Make sure to upgrade to 2.7.0.
Does Spring-WS run under Java 1.3?
Spring Web Services requires Java 1.4 or higher.
Does Spring-WS work under Java 1.4?
Spring Web Services works under Java 1.4, but it requires some effort to make
it work. Java 1.4 is bundled with the older XML parser Crimson, which does not
handle namespaces correctly. Additionally, it is bundled with an older version
of Xalan, which also has problems. Unfortunately, placing newer versions of
these on the class path does not override them. .
The only solution that works is to add newer versions of Xerces and Xalan in
the lib/endorsed directory of your JDK, as explained in those FAQs
(i.e.$JAVA_HOME/lib/endorsed). The following libraries are known to work with
Java 1.4.2:
Library
|
Version
|
|
|
2.8.1
|
|
|
2.7.0
|
|
|
1.3.04
|
|
|
1.2
|
If you want to use WS-Security, note that the
XwsSecurityInterceptor requires Java 5, because an underlying library (XWSS)
requires it. Instead, you can use the Wss4jSecurityInterceptor.
Does Spring-WS work under Java 1.6?
Java 1.6 ships with SAAJ 1.3, JAXB 2.0, and JAXP 1.4 (a custom version of
Xerces and Xalan). Overriding these libraries by putting different version on
the classpath will result in various classloading issues, or exceptions in
org.apache.xml.serializer.ToXMLSAXHandler. The only option for using more
recent versions is to put the newer version in the endorsed directory (see
above).
Why do the Spring-WS unit tests fail under
Mac OS X?
For some reason, Apple decided to include a Java 1.4 compatibility jar with
their JDK 1.5. This jar includes the XML parsers which were included in Java
1.4. No other JDK distribution does this, so it is unclear what the purpose of
this compatibility jar is.
The jar can be found at
/System/Library/Frameworks/JavaVM.framework/Versions/1.5.0/Classes/.compatibility/14compatibility.jar.
You can safely remove or rename it, and the tests will run again.
What is web module?
Spring comes with a full-featured MVC framework for
building web applications. Although Spring can easily be integrated with other
MVC frameworks, such as Struts, Spring’s MVC framework uses IoC to provide for
a clean separation of controller logic from business objects. It also allows
you to declaratively bind request parameters to your business objects. It also
can take advantage of any of Spring’s other services, such as I18N messaging and
validation.
What
is a BeanFactory?
A BeanFactory is an implementation of the factory pattern
that applies Inversion of Control to separate the application’s configuration
and dependencies from the actual application code.
What is AOP Alliance?
AOP Alliance is an open-source project whose goal is to
promote adoption of AOP and interoperability among different AOP
implementations by defining a common set of interfaces and components.
What is Spring configuration file?
Spring configuration file is an XML file. This file
contains the classes information and describes how these classes are configured
and introduced to each other.
What does a simple spring application
contain?
These applications are like any Java application. They
are made up of several classes, each performing a specific purpose within the
application. But these classes are configured and introduced to each other
through an XML file. This XML file describes how to configure the classes,
known as theSpring configuration file.
What is XMLBeanFactory?
BeanFactory has many implementations in Spring. But one of
the most useful one isorg.springframework.beans.factory.xml.XmlBeanFactory,
which loads its beans based on the definitions contained in an XML file. To
create an XmlBeanFactory, pass a java.io.InputStream to the
constructor. The InputStream will provide the XML to
the factory. For example, the following code snippet uses a java.io.FileInputStream to
provide a bean definition XML file toXmlBeanFactory.
BeanFactory factory
= new XmlBeanFactory(new FileInputStream("beans.xml"));
To retrieve the bean from a BeanFactory, call the getBean() method by passing
the name of the bean you want to retrieve.
MyBean myBean
= (MyBean) factory.getBean("myBean")
What
are important ApplicationContext implementations in spring framework?
- ClassPathXmlApplicationContext
– This context loads a context
definition from an XML file located in the class path, treating context
definition files as class path resources.
- FileSystemXmlApplicationContext
– This context loads a context
definition from an XML file in the filesystem.
- XmlWebApplicationContext
– This context loads the context
definitions from an XML file contained within a web application.
Explain Bean lifecycle in Spring framework?
- The
spring container finds the bean’s 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 is bean wiring?
Combining together beans within the Spring container is known as bean wiring or
wiring. When wiring beans, you should tell the container what beans are needed
and how the container should use dependency injection to tie them together.
How do add a bean
in spring application?
<?xml
version="1.0" encoding="UTF-8"?>
<!DOCTYPE
beans PUBLIC "-//SPRING//DTD BEAN//EN"
"http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
<bean id="foo" class="com.act.Foo"/>
<bean
id="bar" class="com.act.Bar"/>
</beans>
What are singleton beans
and how can you create prototype beans?
Beans defined in spring framework are
singleton beans. There is an attribute in bean tag named ‘singleton’ if
specified true then bean becomes singleton and if set to false then the bean
becomes a prototype bean. By default it is set to true. So, all the beans in
spring framework are by default singleton beans.
<beans>
<bean
id="bar" class="com.act.Foo" singleton=”false”/>
</beans>
What are the important
beans lifecycle methods?
There are two important bean lifecycle
methods. The first one is setup which is called when the bean is loaded in to
the container. The second method is the teardown method which is called when
the bean is unloaded from the container.
How can you override beans
default lifecycle methods?
The bean tag has two more important
attributes with which you can define your own custom initialization and destroy
methods. Here I have shown a small demonstration. Two new methods fooSetup and
fooTeardown are to be added to your Foo class.
<beans>
<bean
id="bar" class="com.act.Foo" init-method=”fooSetup”
destroy=”fooTeardown”/>
</beans>
What are Inner Beans?
When wiring beans, if a bean element is
embedded to a property tag directly, then that bean is said to the Inner Bean.
The drawback of this bean is that it cannot be reused anywhere else.
what are the different
types of bean injections?
There are two types of bean injections.
What is Auto wiring?
You can wire the beans as you wish. But
spring framework also does this work for you. It can auto wire the related
beans together. All you have to do is just set the autowire attribute of bean tag
to an autowire type.
<beans>
<bean
id="bar" class="com.act.Foo" Autowire=”autowire type”/>
</beans>
. What are different types
of Autowire types?
There are four different types by which
autowiring can be done.
- byName
- byType
- constructor
- autodetect
What are the different
types of events related to Listeners?
There are a lot of events related to
ApplicationContext of spring framework. All the events are subclasses of
org.springframework.context.Application-Event. They are
- ContextClosedEvent – This is fired when the context is
closed.
- ContextRefreshedEvent – This is fired when the context
is initialized or refreshed.
- RequestHandledEvent – This is fired when the web
context handles any request.
