Spring Bean Definition


The objects that structure the foundation of your application and that are overseen by the Spring IoC compartment are called beans. A bean is an item that is instantiated, amassed, and generally overseen by a Spring IoC holder. These beans are made with the design metadata that you supply to the compartment. For instance, as XML <bean/> definitions which you have just found in the past chapters.

Bean definition contains the data called configuration metadata, which is required for the holder to know the accompanying −

  • How to make a bean
  • Bean's lifecycle details
  • Bean's dependencies

All the above design metadata converts into a lot of the accompanying properties that make up each bean definition.

Sr.No. Properties & Description
1

class

This property is required and indicates the bean class to be utilized to make the bean.

2

name

This property determines the bean identifier particularly. In XMLbased setup metadata, you utilize the id as well as name credits to determine the bean identifier(s).

3

scope

This trait indicates the extent of the items made from a specific bean definition and it will be talked about in bean scopes chapter.

4

constructor-arg

This is utilized to infuse the conditions and will be talked about in resulting chapters.

5

properties

This is utilized to infuse the conditions and will be talked about in resulting chapters.

6

autowiring mode

This is utilized to infuse the conditions and will be talked about in resulting chapters.

7

lazy-introduction mode

A sluggish introduced bean advises the IoC holder to make a bean case when it is first asked for, instead of at the startup.

8

initialization method

A callback to be called soon after every vital property on the bean have been set by the holder. It will be examined in bean life cycle chapter.

9

destruction method

A callback to be utilized when the compartment containing the bean is annihilated. It will be talked about in bean life cycle chapter.

Spring Configuration Metadata

Spring IoC compartment is completely decoupled from the arrangement in which this design metadata is really composed. Following are the three essential techniques to give arrangement metadata to the Spring Container −

  • XML based design file.
  • Annotation-based configuration
  • Java-based configuration

You as of now have perceived how XML-based design metadata is given to the holder, however given us a chance to see another example of XML-based arrangement document with various bean definitions including sluggish instatement, introduction technique, and annihilation strategy −

<?xml adaptation = "1.0" encoding = "UTF-8"?> 

<beans xmlns = "http://www.springframework.org/outline/beans" 

xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance" 

xsi:schemaLocation = "http://www.springframework.org/outline/beans 

http://www.springframework.org/outline/beans/spring-beans-3.0.xsd"> 

<!- - A basic bean definition - > 

<bean id = "..." class = "..."> 

<!- - teammates and design for this bean go here - > 

</bean> 

<!- - A bean definition with languid init set on - > 

<bean id = "..." class = "..." lazy-init = "true"> 

<!- - teammates and design for this bean go here - > 

</bean>

<!- - A bean definition with instatement technique - > 

<bean id = "..." class = "..." init-method = "..."> 

<!- - associates and setup for this bean go here - > 

</bean> 

<!- - A bean definition with pulverization technique - > 

<bean id = "..." class = "..." destroy-method = "..."> 

<!- - associates and setup for this bean go here - > 

</bean> 

<!- - more bean definitions go here - > 

</beans>

You can check Spring Hello World Example to see how to characterize, design and make Spring Beans.

We will examine about Annotation Based Configuration in a different part. It is purposefully talked about in a different section as we need you to get a handle on a couple of other vital Spring ideas, before you begin programming with Spring Dependency Injection with Annotations.







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