AnnotationAutoWiring in spring

Summary

• AnnotationAutoWiring is a mechanism in Spring that allows the framework to automatically detect and inject the dependent beans to the properties of the target bean without the need for explicit configuration.
• In simple words, when we apply autowiring, then Spring looks for the dependent beans in the container and automatically injects them into the target object.
• Benefits:
  • This can save a lot of time and effort, especially in large-scale applications where there are a large number of dependencies between objects.
• Drawbacks:
  • No control of the programmer.
  • It can’t be used for primitive and not recommended for string values.

Syntax

`

<bean class="com.autowire.demo.beans.Account" id="account1">
    <property name="accountId" value="SV-101"/>
    <property name="balance" value="50000.0"/>
</bean>

<bean class="com.autowire.demo.beans.Account" id="account2">
    <property name="accountId" value="SV-102"/>
    <property name="balance" value="100000.0"/>
</bean>

<bean class="com.autowire.demo.beans.Customer" id="customer" autowire="byName">
    <property name="customerName" value="Neeraj"/>
    <property name="account" ref="account2"/>
</bean>

`

Conclusion

• AppConfig.java: Java-based configuration class with @Bean definitions for autowiring.
• application-conf.xml: XML-based configuration for autowiring Customer and Account beans.
• Customer.java: A class representing a customer with an account dependency.
• Person.java: A class to demonstrate autowiring using Java configuration.
• UseCustomer.java and UsePerson.java: Main application classes that load the Spring context and display the injected beans.
• Here, we’re annotating the AppConfig class with @Configuration @ComponentScan to allow Spring IoC to scan all the beans defined under AppConfig.

Note:

• The jar spring-aop is required for annotation processing and let spring automatically scan the bean from Configuration class.