What is Spring?
Spring
is a lightweight inversion of control and aspect-oriented container framework.
Explain 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.
Framework - Spring provides most of
the intra functionality leaving rest of the coding to thedeveloper
What are the different modules in spring
framework?
The Core container module
Application context module
AOP module (Aspect Oriented
Programming)
JDBC abstraction and DAO module
O/R mapping integration module
(Object/Relational)
Web module
MVC framework module
What is the Core container module?
This
module is provides the fundamental functionality of the spring framework. In
this module Bean Factory is the heart of any spring-based application. The
entire framework was built on the top of this module. This module makes the
spring container.
What is Application context module?
The
Application context module makes spring a framework. This module extends the
concept of Bean Factory, providing support for internationalization (I18N)
messages, application lifecycle events, and validation. This module also
supplies many enterprise services such JNDI access, EJB integration, remoting, and scheduling. It also provides support to other
framework.
What is AOP module?
The
AOP module is used for developing aspects for our Spring-enabled application.
Much of the support has been provided by the AOP Alliance in order to ensure
the interoperability between spring and other AOP frameworks. This module also
introduces metadata programming to spring. Using spring’s metadata support, we
will be able to add annotations to our source code that instruct spring on
where and how to apply aspects.
What is JDBC abstraction and DAO
module?
Using
this module we can keep up the database code clean and simple, and prevent
problems that result from a failure to close database resources. A new layer of
meaningful exceptions on top of the error messages given by several database
servers is bought in this module. In addition, this module uses spring’s AOP
module to provide transaction management services for objects in a spring application.
What are object/relational mapping integration
module?
Spring
also supports for using of an object/relational mapping (ORM) tool over
straight JDBC by providing the ORM module. Spring provide support to tie into
several popular ORM frameworks, including Hibernate, JDO, and iBATIS SQL Maps. Spring’s transaction management supports
each of these ORM frameworks as well as JDBC.
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 is a Bean Factory?
A
Bean Factory 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 the Spring configuration file.
What is XMLBeanFactory?
Bean
Factory 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 to XmlBeanFactory.
BeanFactory factory = new XmlBeanFactory(newFileInputStream(”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 Application Context 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 file system.
XmlWebApplicationContext
– This context loads the context definitions from an XML file contained within a web application.
Explain Bean lifecycle
in Spring framework?
1.
The spring container finds the bean’s definition from the XML file and
instantiates the bean.
2.
Using the dependency injection, spring populates all of the properties as
specified in the bean definition.
3.
If the bean implements the BeanNameAware interface,
the factory calls setBeanName() passing the bean’s ID.
4.
If the bean implements the BeanFactoryAware
interface, the factory calls setBeanFactory(), passing an instance of itself.
5.
If there are any Bean Postprocessors associated with the bean, their post- ProcessBeforeInitialization() methods will be called.
6.
If an init-method is specified for the bean, it will be called.
7.
Finally, if there are any Bean Postprocessors associated with the bean, theirpostProcessAfterInitialization() methods will be called.
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