Sometimes dependencies between beans may not be direct but you may still want to ensure that a specific bean is initialized before another bean. For example in one bean there is a static block which has to be executed before another bean is initialized. You can use Spring @DependsOn annotation…
Spring @Autowired annotation is used to automatically inject dependencies. Where to apply @Autowired annotation You can apply the @Autowired annotation to setter methods. See example. You can apply the @Autowired annotation to constructors. See example. You can apply @Autowired to fields. See example. You can also apply the annotation to…
For autowiring in Spring apart from using @Autowired annotation there is also support for JSR 330’s @Inject annotation and JSR-250 @Resource annotation. In this post we’ll see how to use Spring @Resource annotation for autowiring. @Resource annotation in Spring @Resource annotation can be used on fields or bean property setter…
Spring @Configuration annotation helps in creating Java based configuration in Spring rather than relying on XML based configuration. Any class annotated with @Configuration indicates that a class declares one or more @Bean methods that are processed by the Spring container to generate bean definitions and manage the overall bean lifecycle.…
Spring @Required annotation is used with a method, typically a setter method thus making setter dependency injection for that property mandatory. RequiredAnnotationBeanPostProcessor class Registering RequiredAnnotationBeanPostProcessor class is required to use @Required annotation. A default RequiredAnnotationBeanPostProcessor will be registered by the “context:annotation-config” and “context:component-scan” XML tags. Spring @Required annotation examples In…
This post shows how to use @Import annotation in Spring. In an application you may have several bean definitions making your @Configuration class quite huge. Rather than putting all the bean definitions in a single configuration class you can break your configuration into several small configurations module wise. Then using…
Using Spring @Conditional annotation you can conditionally register a component. With @Conditional annotation you need to specify a condition and the component is registered only if the condition is true. For specifying the condition you need to implement org.springframework.context.annotation.Condition interface. Where to use @Conditional annotation The @Conditional annotation may be…
Spring @Value annotation at the field or method/constructor parameter level is used to inject a value. @Value annotation in Spring can be used in the following ways- Directly to inject a value at the field, method or constructor level. Using @Value annotation you can also assign a value by reading…
In this post we’ll see how to externalize your configuration to a properties file in Spring and how to read values from properties file in Spring using XML configuration and using @PropertySource annotation. It is a best practice to put application specific settings into separate properties files rather than hardcoding…
The Spring Expression Language (“SpEL”) is an expression language that supports querying and manipulating an object graph at runtime. In this post we’ll see examples of using SpEL with both XML and annotation based configuration. The expression language supports the following functionality: Literal expressions Boolean, relational and mathematical operators Regular…
