1. What are the different types of AutoProxying?
► BeanNameAutoProxyCreator
► DefaultAdvisorAutoProxyCreator
► Metadata autoproxying
2. 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
► Around : org.aopalliance.intercept.MethodInterceptor
► Before : org.springframework.aop.BeforeAdvice
► After : org.springframework.aop.AfterReturningAdvice
► Throws : org.springframework.aop.ThrowsAdvice
3. What are the different points where weaving can be applied?
► Compile Time
► Classload Time
► Runtime
The process of applying aspects to a target object to create a new proxy object is called as Weaving. The aspects are woven into the target object at the specified joinpoints.
A proxy is an object that is created after applying advice to a target object. When you think of client objects the target object and the proxy object are the same.
A target is the class that is being advised. The class can be a third party class or your own class to which you want to add your own custom behavior. By using the concepts of AOP, the target class is free to center on its major concern, unaware to anyadvice that is being applied.
7. What is an Introduction in AOP?
An introduction allows the user to add new methods or attributes to an existing class. This can then be introduced to an existing class without having to change the structure of the class, but give them the new behavior and state.
A pointcut is something that defines at what joinpoints an advice should be applied. Advices can be applied at any joinpoint that is supported by the AOP framework. These Pointcuts allow you to specify where theadvice can be applied.
Advice is the implementation of an aspect. It is something like telling your application of a new behavior. Generally, and advice is inserted into an application at joinpoints.
A joinpoint is a point in the execution of the application where an aspect can be plugged in. This point could be a method being called, an exception being thrown, or even a field being modified. These are the points where your aspect's code can be inserted into the normal flow of your application to add new behavior.
An aspect is the cross-cutting functionality that you are implementing. It is the aspect of your application you are modularizing. An example of an aspect is logging. Logging is something that is required throughout an application. However, because applications tend to be broken down into layers based on functionality, reusing a logging module through inheritance does not make sense. However, you can create a logging aspect and apply it throughout your application using AOP.
12. What are different types of Autowire types?
There are four different types by which autowiring can be done.
► byName
► byType
► constructor
► autodetect
13. What are the different types of bean injections?
There are two types of bean injections.
1. By setter
2. By constructor
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.
15. 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.
16. 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.
17. 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.
18. 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 BeanPostProcessors 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 BeanPostProcessors associated with the bean, their postProcessAfterInitialization() methods will be called.
BeanFactory has many implementations in Spring. But one of the most useful one is org.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.
20. 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.
21. 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.
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.
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.
24. 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.
25. 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.
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.
27. What is Application context module?
The Application context module makes spring a framework. This module extends the concept of BeanFactory, 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.
28. What is the Core container module?
This module is provides the fundamental functionality of the spring framework. In this module BeanFactory 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.
29. 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
30. 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 as DelegatingVariableResolver
31. 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
32. 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.
33. 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.
34. 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.
35. 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
