In this article, we are going to talk about spring in java Framework in an easy manner for beginners. Spring Framework is now being used frequently 

What is Spring Framework?

Spring is a lightweight framework. Because it supports numerous frameworks, like Struts, Hibernate, Tapestry, EJB, JSF, etc., it can be viewed as a framework of frameworks. In a broader sense, the framework can be thought of as a platform where we can organize our efforts to solve various technological issues.

A number of modules, including IOC, AOP, DAO, Context, ORM, WEB MVC, etc., are included in the Spring framework. These modules will be covered on the next page. Let's start by comprehending IOC and Dependency Injection.

Spring Features

• Flexible
• Productive
• Fast
• Secure
• Supportive
• Everywhere

Everywhere there is spring:

• Everywhere Spring is one of the most widely used frameworks in the world. It is employed in Java enterprise application development. It can be used to develop web apps, cloud-based services, web services, etc. 
• Global tech companies like Google, Alibaba, Amazon, Oracle, etc. use it. Worldwide Java developers rely on the libraries provided by Spring. It is utilized practically everywhere, including in banking, IoT connections, eCommerce applications, and streaming TV.

Spring is Convenient:

• Spring offers developers adaptable third-party libraries and extensions to aid in the creation of applications. 
• The two key characteristics of Spring that make it adaptable for developing enterprise applications are Inversion of Control (IoC) and Dependency Injection (DI). 
• Spring offers a number of tools that aid programmers in creating resilient, secure microservices for the web, as well as complex streaming data flow for enterprise applications.

Spring is Productive:

•  There is no denying that Spring is a productive framework, and with the addition of the Spring Boot project, Spring has become even more so. Spring Boot includes all requirements and pre-configured settings.
•  To speed up the construction of microservices, it has an embedded web server. The integration of spring projects, which aid in the creation of consecutive applications, is crucial.
•  For instance, it offers a framework for building applications, Spring Data for connecting databases, Spring Cloud for working with the cloud, and Spring Security for security. 
• Therefore, all we need to do is enter them into our application in accordance with the requirements, and it will be ready.

Spring is Quick: 

• The design and architecture of the Spring framework greatly enhance its performance. With a focus on performance, the Spring foundation enables applications to start up quickly, run steadily, and shut down quickly.
•  The reactive programming model is supported by Spring projects for increased performance and efficiency. A Spring Initializer utility is offered by Spring to help you launch your application rapidly. auto-configured Spring Boot provides developers with the tools they need to build applications quickly, including embedded web servers.
•  The problem and requirement for a server restart are eliminated by adding Live Reload to Spring DevTools.

Spring is Secure:

•  Spring is secure by nature, and the Java language also offers security. However, for further protection, we can use Spring Security. One of the Spring projects, Spring Security, is made to handle the security of any Spring application. 
• It is simple to integrate with the application because it is a component of the Spring framework. Security concerns are handled by spring in a timely manner.
•  To keep our data and programs safe and secure, it carefully monitors third-party dependencies and releases updates on a regular basis.

Spring is Supportive:

• Supportive of developers globally, Spring has a huge, global, gigantic, and diversified community. No matter where you live or your degree of understanding, Spring offers support for everyone. 
• It benefits people of all ages and skill levels, from total beginners to business professionals.
•  The Spring community offers a wide range of resources, including official training and certification as well as videos, manuals, tutorials, meetups, and support.

Spring Modules

AOP, Aspects, Instrumentation, JDBC, ORM, OXM, JMS, Transaction, Web, Servlet, Struts, and many other modules make up the Spring framework. The following diagram shows how these modules are categorized into Test, Core Container, AOP, Aspects, Instrumentation, Data Access / Integration, and Web (MVC / Remoting).

Test: 

• This layer offers support for JUnit and TestNG testing.

Spring Core Container:

• Core, beans, context, and expression language (EL) modules are all contained in the Spring Core container.

Core And Beans:

• These modules, Core and Beans, offer IOC and Dependency Injection capabilities:

Context: 

• This module supports EJB, JMS, basic remote access, and internet

Experience Language:

• It is an expansion of the EL described in JSP, or expression language. Invoking methods, accessing collections and indexers, named variables, logical and arithmetic operators, retrieving objects by name, and other functions are supported.

AOP, Aspects, and Instrumentation: 

• These modules facilitate the implementation of aspect-oriented programming, where the code can be decoupled via Advice, Pointcuts, etc.

• AspectJ integration is supported through the aspects module.

• Class instrumentation and class loader implementations are supported by the instrumentation module.

Data Access / Integration:

• This category includes the JMS, Transaction, ORM, OXM, and JDBC modules. In essence, these modules offer assistance while interacting with the database.

Web:

• Web-Servlet, Web-Struts, and Web-Portlet are all members of this category. These modules offer assistance in building a web application.

Spring MVC

What is MVC?

         The architectural design pattern known as Model-View-Controller (MVC) divides an application into three primary logical parts: the model, the view, and the controller. Each of these parts was created to deal with a particular application development task. MVC is one of the most popularly employed industry-standard web development frameworks for making projects that are scalable and extendable.

Spring MVC Architecture:

Spring MVC View:

• The view is a part of the MVC architecture that is used to give the user what they requested in terms of a user interface output. Any HTML or JSP file can be used as a View page.
• To get the user's desired view, Spring MVC internally employs a view resolver. The view in the Spring application can be configured in a number of different ways. To configure the view, we can use XML, Java code, and property files.
• The ViewResolver and View interfaces that Spring MVC defines allow you to render models in a browser without being restricted to particular view technology. A mapping between view names and actual views is provided by ViewResolver. The view focuses on the data preparation before giving it to the particular technological view.

Implementations of ViewResolver

AbstractCachingViewResolver:

The view instance is cached using this class. Certain view technologies perform better when caching is used. Nevertheless, by setting the cache property to false, we can disable the cache.

XmlViewResolver:

The XML view files are handled by this class. It takes an XML configuration file with the same DTD as Spring's XML bean factories as input.

ResourceBundleViewResolver:

 It makes use of ResourceBundle bean definitions identified by the bundle base name. It utilizes the value of the property [viewname] for every view that it is supposed to resolve. (class) is used as the view class, and the [viewname].URL property's value is used as the view URL.

UrlBasedViewResolver:

  It used to have an impact on the implicit mapping definition-free direct resolution of logical view names to URLs.

InternalResourceViewResolver:

It supports InternalResourceView and subclasses like JstlView and TilesView and is a useful subclass of UrlBasedViewResolver.

FreeMarkerViewResolver:

This class supports FreeMarkerView and is a subclass of UrlBasedViewResolver.

ContentNegotiatingViewResolver:

Based on the request file name, it is utilized to resolve a view.

How does Spring ViewResolver function?

The controller engages with the ViewResolver when a user requests a view. The controller receives the required view from the ViewResolver, who then passes the controller on to the user.