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|Spring framework Vs Node JS|
|Creation Date||September 2002||2009|
|Modules/Extensions/Plugins||10 000||9 001|
|Difficulty level||Intermediate Advanced Master||Advanced|
|Browser support||All of them||All of them|
|Documentation||API Documentation Forum Tutorials PDF eBook||API Documentation|
|Sync file manager||Good||Basic|
|Operating system server||JVM Compatible Android iOS||Cross-platform|
|Read more differences @ Spring Vs Node JS|
1) What is Spring Framework?
2) What are the benefits of Spring Framework?
3) What are the Spring framework modules?
4) Explain the Core Container (Application context) module in Spring?
5) BeanFactory – BeanFactory implementation example in Spring?
Q1) What is Spring?
Spring is an open source development framework for Enterprise Java. The core features of the Spring Framework can be used in developing any Java application, but there are extensions for building web applications on top of the Java EE platform. Spring framework targets to make Java EE development easier to use and promote good programming practice by enabling a POJO-based programming model.
Q2) What are benefits of Spring Framework?
Q3) Which are the Spring framework modules?
The basic modules of the Spring framework are :
Q4) Explain the Core Container (Application context) module
This is the basic Spring module, which provides the fundamental functionality of the Spring framework. BeanFactory is the heart of any spring-based application. Spring framework was built on the top of this module, which makes the Spring container.
Q5) BeanFactory – BeanFactory implementation example
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.
The most commonly used BeanFactory implementation is the XmlBeanFactory class.
The most useful one is org.springframework.beans.factory.xml.XmlBeanFactory, which loads its beans based on the definitions contained in an XML file. This container reads the configuration metadata from an XML file and uses it to create a fully configured system or application.
Q7) Explain the 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.
Q8) Explain the JDBC abstraction and DAO module
With the JDBC abstraction and DAO module we can be sure that we keep up the database code clean and simple, and prevent problems that result from a failure to close database resources. It provides a layer of meaningful exceptions on top of the error messages given by several database servers. It also makes use of Spring’s AOP module to provide transaction management services for objects in a Spring application.
Q9) Explain the 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 provides 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.
Q10) Explain the web module
The Spring web 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.
Q11) Explain the Spring MVC module
MVC framework is provided by Spring for building web applications. Spring can easily be integrated with other MVC frameworks, but Spring’s MVC framework is a better choice, since it uses IoC to provide for a clean separation of controller logic from business objects. With Spring MVC you can declaratively bind request parameters to your business objects.
Q12) 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.
Q13) What is Spring IoC container?
The Spring IoC is responsible for creating the objects,managing them (with dependency injection (DI)), wiring them together, configuring them, as also managing their complete lifecycle.
Q14) What are the benefits of IOC?
IOC or dependency injection minimizes the amount of code in an application. It makes easy to test applications, since no singletons or JNDI lookup mechanisms are required in unit tests. Loose coupling is promoted with minimal effort and least intrusive mechanism. IOC containers support eager instantiation and lazy loading of services.
Q15) What are the common implementations of the ApplicationContext?
The FileSystemXmlApplicationContext container loads the definitions of the beans from an XML file. The full path of the XML bean configuration file must be provided to the constructor.
The ClassPathXmlApplicationContext container also loads the definitions of the beans from an XML file. Here, you need to set CLASSPATH properly because this container will look bean configuration XML file in CLASSPATH.
The WebXmlApplicationContext: container loads the XML file with definitions of all beans from within a web application.
Q16) What is the difference between Bean Factory and ApplicationContext?
Application contexts provide a means for resolving text messages, a generic way to load file resources (such as images), they can publish events to beans that are registered as listeners. In addition, 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. The application context implements MessageSource, an interface used to obtain localized messages, with the actual implementation being pluggable.
Q17) What does a Spring application look like?
Q18) What is Dependency Injection in Spring?
Dependency Injection, an aspect of Inversion of Control (IoC), is a general concept, and it can be expressed in many different ways.This concept says 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 (the IOC container) is then responsible for hooking it all up.
Q19) What are the different types of IoC (dependency injection)?
Q20) Which DI would you suggest Constructor-based or setter-based DI?
You can use both Constructor-based and Setter-based Dependency Injection. The best solution is using constructor arguments for mandatory dependencies and setters for optional dependencies.
Q21) What are Spring beans?
Spring beans scope interview questions - The Spring Beans are Java Objects that form the backbone of a Spring application. They are instantiated, assembled, and managed by the Spring IoC container. These beans are created with the configuration metadata that is supplied to the container, for example, in the form of XML definitions.
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.
Q22) What does a Spring Bean definition contain?
A Spring Bean definition contains all configuration metadata which is needed for the container to know how to create a bean, its lifecycle details and its dependencies.
Q23) How do you provide configuration metadata to the Spring Container?
There are three important methods to provide configuration metadata to the Spring Container:
Q24) How do you define the scope of a bean?
When defining a in Spring, we can also declare a scope for the bean. It can be defined through the scope attribute in the bean definition. For example, when Spring has to produce a new bean instance each time one is needed, the bean’sscope attribute to be prototype. On the other hand, when the same instance of a bean must be returned by Spring every time it is needed, the the bean scope attribute must be set to singleton.
Q25) Explain the bean scopes supported by Spring
There are five scoped provided by the Spring Framework supports following five scopes:
The default scope of a Spring Bean is Singleton.
Q26) Are Singleton beans thread safe in Spring Framework?
No, singleton beans are not thread-safe in Spring framework.
Q27) Explain Bean lifecycle in Spring framework
Q28) Which are the important beans lifecycle methods? Can you override them?
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.
The bean tag has two important attributes (init-method and destroy-method) with which you can define your own custom initialization and destroy methods. There are also the correspondive annotations(@PostConstruct and @PreDestroy).
Q29) What are inner beans in Spring?
When a bean is only used as a property of another bean it can be declared as an inner bean. Spring’s XML-based configuration metadata provides the use of element inside the or elements of a bean definition, in order to define the so-called inner bean. Inner beans are always anonymous and they are always scoped as prototypes.
Q30) How can you inject a Java Collection in Spring?
Spring offers the following types of collection configuration elements:
Q31) What is bean wiring?
Wiring, or else bean wiring is the case when beans are combined together within the Spring container. When wiring beans, the Spring container needs to know what beans are needed and how the container should use dependency injection to tie them together.
Q32) What is bean 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 a bean by inspecting the contents of the BeanFactorywithout using and elements.
Q33) Explain different modes of auto wiring?
The autowiring functionality has five modes which can be used to instruct Spring container to use autowiring for dependency injection:
Q34) Are there limitations with autowiring?
Limitations of autowiring are:
Q35) Can you inject null and empty string values in Spring?
Yes, you can.
Q36) What is Spring Java-Based Configuration? Give some annotation example.
Java based configuration option enables you to write most of your Spring configuration without XML but with the help of few Java-based annotations.
An example is a @Configuration annotation, that indicates that the class can be used by the Spring IoC container as a source of bean definitions. Another example is the@Bean annotated method that will return an object that should be registered as a bean in the Spring application context.
Q36) What is Annotation-based container configuration?
An alternative to XML setups is provided by an annotation-based configuration which relies on the bytecode metadata for wiring up components instead of angle-bracket declarations. Instead of using XML to describe a bean wiring, the developer moves the configuration into the component class itself by using annotations on the relevant class, method, or field declaration.
Q37) How do you turn on annotation wiring?
Annotation wiring is not turned on in the Spring container by default. In order to use annotation based wiring, we must enable it in our Spring configuration file by configuring element.
Q38) @Required annotation
This annotation simply indicates that the affected bean property must be populated at configuration time, through an explicit property value in a bean definition or through autowiring. The container throws BeanInitializationException if the affected bean property has not been populated.
Q39) @Autowired annotation
The @Autowired annotation provides more fine-grained control over where and how autowiring should be accomplished. It can be used to autowire bean on the setter method just like @Required annotation, on the constructor, on a property or pn methods with arbitrary names and/or multiple arguments.
Q40) @Qualifier annotation
When there are more than one beans of the same type and only one is needed to be wired with a property, the@Qualifier annotation is used along with @Autowired annotation to remove the confusion by specifying which exact bean will be wired.
Q41) How can JDBC be used more efficiently in the Spring framework?
When using the Spring JDBC framework the burden of resource management and error handling is reduced. So developers only need to write the statements and queries to get the data to and from the database. JDBC can be used more efficiently with the help of a template class provided by Spring framework, which is the JdbcTemplate
JdbcTemplate class provides many convenience methods for doing things such as converting database data into primitives or objects, executing prepared and callable statements, and providing custom database error handling.
Q43) Spring DAO support
The Data Access Object (DAO) support in Spring is aimed at making it easy to work with data access technologies like JDBC, Hibernate or JDO in a consistent way. This allows us to switch between the persistence technologies fairly easily and to code without worrying about catching exceptions that are specific to each technology.
Q44) What are the ways to access Hibernate by using Spring?
There are two ways to access Hibernate with Spring:
Q45) ORM’s Spring support
Spring supports the following ORM’s:
Q46) How can we integrate Spring and Hibernate using HibernateDaoSupport?
Use Spring’s SessionFactory called LocalSessionFactory. The integration process is of 3 steps:
Q47) Types of the transaction management Spring support
Spring supports two types of transaction management:
Q48) What are the benefits of the Spring Framework’s transaction management?
Q49) Which Transaction management type is more preferable?
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. Declarative transaction management is preferable over programmatic transaction management though it is less flexible than programmatic transaction management, which allows you to control transactions through your code.
Q50) Explain AOP
Aspect-oriented programming, or AOP, is a programming technique that allows programmers to modularize crosscutting concerns or behavior that cuts across the typical divisions of responsibility, such as logging and transaction management.
The core construct of AOP is the aspect, which encapsulates behaviors affecting multiple classes into reusable modules. It ia a module which has a set of APIs providing cross-cutting requirements. For example, a logging module would be called AOP aspect for logging. An application can have any number of aspects depending on the requirement. In Spring AOP, aspects are implemented using regular classes annotated with the @Aspect annotation (@AspectJ style).
Q52) What is the difference between concern and cross-cutting concern in Spring AOP
The Concern is behavior we want to have in a module of an application. A Concern may be defined as a functionality we want to implement.
The cross-cutting concern is a concern which is applicable throughout the application and it affects the entire application. For example, logging, security and data transfer are the concerns which are needed in almost every module of an application, hence they are cross-cutting concerns.
The join point represents a point in an application where we can plug-in an AOP aspect. It is the actual place in the application where an action will be taken using Spring AOP framework.
The advice is the actual action that will be taken either before or after the method execution. This is an actual piece of code that is invoked during the program execution by the Spring AOP framework.
Spring aspects can work with five kinds of advice:
The pointcut is a set of one or more joinpoints where an advice should be executed. You can specify pointcuts using expressions or patterns.
Q56) What is Introduction?
An Introduction allows us to add new methods or attributes to existing classes.
Q57) What is Target object?
A target object is an object being advised by one or more aspects. It will always be a proxy object. It is also referred to as the advised object.
Q58) What is a Proxy?
A proxy is an object that is created by applying advice to a target object. When you think of client objects the target object and the proxy object are the same.
Q59) What are the different types of AutoProxying?
Q60) What is Weaving? What are the different points where weaving can be applied?
Weaving is the process of linking aspects with other application types or objects to create an advised object.
Weaving can be done at compile time, at load time, or at runtime.
Q61) Explain XML Schema-based aspect implementation?
In this implementation case, aspects are implemented using regular classes along with XML based configuration.
Q62) Explain annotation-based (@AspectJ based) aspect implementation
This implementation case (@AspectJ based implementation) refers to a style of declaring aspects as regular Java classes annotated with Java 5 annotations.
Q63) What is Spring MVC framework?
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 a clean separation of controller logic from business objects. It also allows to declaratively bind request parameters to business objects.
The Spring Web MVC framework is designed around a DispatcherServlet that handles all the HTTP requests and responses.
The WebApplicationContext is an extension of the plain ApplicationContext that has some extra features necessary for web applications. It differs from a normal ApplicationContext in that it is capable of resolving themes, and that it knows which servlet it is associated with.
Q66) What is Controller in Spring MVC framework?
Controllers provide access to the application behavior that you typically define through a service interface. Controllers interpret user input and transform it into a model that is represented to the user by the view. Spring implements a controller in a very abstract way, which enables you to create a wide variety of controllers.
Q67) @Controller annotation
The @Controller annotation indicates that a particular class serves the role of a controller. Spring does not require you to extend any controller base class or reference the Servlet API.
Q68) @RequestMapping annotation
@RequestMapping annotation is used to map a URL to either an entire class or a particular handler method.
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