CODEWITHSUNDEEP
javaxmlspringspring-bootspring-mvc
Ricky
Ricky

Reputation: 705

Use of Bean configuration XML File

I am a new user of Spring framework. I am facing some confusion in understanding the difference between core spring framework and spring boot. As far as I understand, Spring boot is a framework which performs the initial setup automatically (like Setting up Maven dependencies and downloading the jar files) and comes with an embedded Tomcat server which makes it ready to deploy in just one click., Whereas, Spring MVC requires manual setup. All the tutorials that I watched for core spring show bean configuration using bean factory which configures the beans using a .XML file. In Spring boot, this bean configuration file is absent. My question is, what is the use of this bean configuration file? I did not find any legitimate use of this file in making a REST service with spring. I didn't see any use of the Application Context, Bean Factory in creating web application. Can someone point out how can bean factory be used in Spring web apps? Is there any fundamental difference between core spring and spring boot other than the additional components?

Upvotes: 0

Views: 522

Answers (1)

chrylis -cautiouslyoptimistic-
chrylis -cautiouslyoptimistic-

Reputation: 77177

The Spring application context is essentially the "pool" of beans (service objects, which include controllers, converters, data-access objects, and so on) and related information that define an application; I recommend the reference introduction. In theory, you can get complicated with the context setup and have hierarchical organization and such, but in most real-world cases you just have a single plain context.

Inside this context you need to install all of the beans that provide the logic for your application. There are several possible ways to do this, but the two main ways are by providing XML files with have directives like bean (define an individual bean) or component-scan (automatically search for classes with certain annotations, including @Controller) and by using Java classes annotated with @Configuration, which can use annotations and @Bean methods.

The XML style is generally older, and newer applications mostly use Java configuration, but both provide entries that are collected into the context, and you can use both simultaneously. However, in any application, you have to provide some way of getting the registration started, and you will typically have one "root" XML file or configuration class that then imports other XML files and/or configuration classes. In a legacy web.xml-based application, you specify this in your servlet configuration file.

Spring Boot is, as you said, essentially a collection of ready-to-go configuration classes along with a mechanism for automatically detecting configurations and activating them. Even this requires a configuration root, though! This is the @EnableAutoConfiguration instruction, frequently used through its composite @SpringBootApplication. The application context and configuration mechanisms work normally once Boot finds them and pulls them in. Spring knows where to get started because you give it an explicit instruction to build a context starting with that entry point, usually with SpringApplication.run(MyApplication.class, args).

The embedded-server configuration just happens to be a particular set of configuration that is really useful and comes with one of the Boot starter packages. There's nothing there that you couldn't do in a non-Boot application.

Upvotes: 1

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