Spring 3 bean instantiation sequence

spring boot bean creation order
spring configuration order
spring boot delay bean creation
spring component scan order
spring boot bean configuration
spring bean example
spring autowired order
spring import order

Is there anyway to specify order in which beans to be instantiated? i.e. I want specific beans to be instantiated before other beans, its like startup sequence.

I am using Spring 3.2 and annotation based declaration method.

If bean A depends on bean B by defining <property/>, @Autowired or <constructor-arg/> then the order is forced and fixed by the Spring container. No problem here.

But if you want to enforce specific order of bean creation which is not expressed via explicit dependencies feel free to use:

<bean id="A" depends-on="B"/>
<bean id="B"/>

or better (with annotations, works also with @Bean Java configuration):

@Service
@DependsOn("B")
public class A {}

or even better... don't use it. These constructs are a code smell and often suggest you have some nasty invisible dependency between your components.

when is a spring bean instantiated, when the getBean method is called for the first time. Let us now learn about various bean instantiation methods in Spring. Bean Instantiation Methods in Spring. There are multiple ways of instantiating beans and you can instruct Spring to use the one which fits your needs. Bean Instantiation using Constructors. Using constructors for instantiating bean is a good choice. By default Spring reflectively invokes the no argument constructor of a bean and gets an instance.

Agreed with the answer provided by Tomasz. If you know that bean A depends on bean B then this is right approach.

Sometimes you have logic that should be executed before all beans instantiation. In this case you can use BeanFactoryPostProcessor. Spring creates and executes BeanFactoryPostProcessors first and after that only all other beans. At the same time if your BeanFactoryPostProcessor depends on some bean A you can use property or constructor injection. In this case Spring will create bean A first, then your BeanFactoryPostProcessor, call BeanFactoryPostProcessor and after that only instatiate all other beans in the context.

why are interfaces recommended for spring beans?, /> , such as: init-method , destroy-method , autowiring , lazy-init , dependency-check , depends-on , scope . I am using some third-part jars that PARTLY migrated to spring. The pain point is that there are lots of initialization module that mot migrated to spring. There initialization module need to be ex

You can use the Ordered interface on your bean to define ordering relative to other beans.

Spring @Bean annotation tutorial, 4.2.3. Bean visibility. A feature unique to JavaConfig feature is bean visibility. The application context being instantiated agaist the XML file will be the 'owning'​  Priority is for Bean3 and Bean 2 to be completely instantiated before Bean1 gets instantiated, i.e. when Spring container comes up. These beans are in seperate JARS, and Bean2 reference into Bean1 is not using Autowired. Instead a service locator is giving it a reference. We are using Spring 2.5.2 and not using XML for instantiation of beans.

Further,if you use BeanFactoryPostProcessor as emamedov said, Ordered interface can be implemented to control BeanFactoryPostProcessor instance sequence.

constructor arguments and property values to set in the newly created bean. Now, an example of using the BeanFactory for IoC type 3 (constructor-based to manually be explicitly registered, with a code sequence such as the following: You may want to include log4j.properties anyways, at least for Spring startup - until Spring has initialized your logging bean, it will use whatever the defaults are for its internal logging, and typically, if you're using Log4J, that will be the log4j.properties file defined on the classpath.

3. @DependsOn. We should use this annotation for specifying bean dependencies. Spring guarantees that the defined beans will be initialized  Running logic during/after Spring application's startup is a common scenario, but one that causes multiple problems. In order to benefit from Inverse of Control, we naturally need to renounce partial control over the application's flow to the container – which is why instantiation, setup logic on startup, etc needs special attention.

Spring's BeanFactoryPostProcessor and Bean Creation Order 3: private SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd"); JavaConfig makes available each of the four standard scopes specified in Section 3.4, "Bean Scopes" of the Spring reference documentation. The DefaultScopes class provides string constants for each of these four scopes. SINGLETON is the default, and can be overridden by supplying the scope attribute to @Bean annotation:

Example Project. Dependencies and Technologies Used: Spring Context 4.2.3.​RELEASE: Spring Context. JDK 1.8; Maven 3.0.4  The BeanPostProcessor interface defines callback methods that you can implement to provide your own instantiation logic, dependency-resolution logic, etc. You can also implement some custom logic after the Spring container finishes instantiating, configuring, and initializing a bean by plugging in one or more BeanPostProcessor implementations.

Comments
  • In my practice instantiation sequence is equal to order in xml config file. But there may be exceptions..
  • I used this to set the spring.active.profile setting from a system properties file. Works great!