Bean lifecycle overview in Spring Boot - Step-by-Step Execution

Concept Flow - Bean lifecycle overview

Bean Definition Loaded

↓

Bean Instantiation

↓

Populate Properties

↓

BeanNameAware.setBeanName()

↓

BeanFactoryAware.setBeanFactory()

↓

Pre-initialization PostProcessors

↓

InitializingBean.afterPropertiesSet()

↓

Custom init-method

↓

Bean Ready to Use

↓

Container Shutdown

↓

DisposableBean.destroy()

↓

Custom destroy-method

↓

Bean Destroyed

This flow shows the main steps a Spring Bean goes through from creation to destruction.

Execution Sample

Spring Boot

public class MyBean implements InitializingBean, DisposableBean {
  @Override
  public void afterPropertiesSet() { System.out.println("Init"); }
  @Override
  public void destroy() { System.out.println("Destroy"); }
}

A simple bean that prints messages during initialization and destruction phases.

Execution Table

Step	Action	Method Called	State/Output
1	Bean definition loaded by Spring	N/A	Bean metadata ready
2	Spring creates bean instance	Constructor	Bean object created
3	Spring sets bean properties	Setter methods	Properties set
4	Spring calls setBeanName()	BeanNameAware.setBeanName()	Bean name injected
5	Spring calls setBeanFactory()	BeanFactoryAware.setBeanFactory()	Bean factory injected
6	Spring applies pre-initialization processors	BeanPostProcessor.postProcessBeforeInitialization()	Bean processed
7	Spring calls afterPropertiesSet()	InitializingBean.afterPropertiesSet()	Custom init logic runs
8	Spring calls custom init-method	Custom init method	Additional init logic runs
9	Bean is ready for use	N/A	Bean fully initialized
10	Container shutdown begins	N/A	Shutdown triggered
11	Spring calls destroy()	DisposableBean.destroy()	Cleanup logic runs
12	Spring calls custom destroy-method	Custom destroy method	Additional cleanup runs
13	Bean destroyed and removed	N/A	Bean lifecycle ends

💡 Bean lifecycle ends after destruction methods complete during container shutdown.

Variable Tracker

Variable	Start	After Instantiation	After Properties Set	After Initialization	After Destruction
Bean Instance	null	Created	Properties Set	Initialized	Destroyed
Bean Name	null	Injected	Injected	Injected	Injected
Bean Factory	null	Injected	Injected	Injected	Injected

Key Moments - 3 Insights

Why does Spring call setBeanName() before initialization?

Spring calls setBeanName() early so the bean knows its own name before any initialization logic runs, as shown in step 4 of the execution_table.

What is the difference between afterPropertiesSet() and a custom init-method?

afterPropertiesSet() is from the InitializingBean interface and runs automatically, while a custom init-method is a user-defined method configured in the bean definition; both run during initialization (steps 7 and 8).

When does the bean get destroyed?

The bean is destroyed during container shutdown, after the destroy() method and custom destroy-method run, as shown in steps 11-13.

Visual Quiz - 3 Questions

Look at the execution_table, at which step does Spring inject the bean's name?

A Step 2

B Step 4

C Step 7

D Step 10

💡 Hint

Check the 'Method Called' column for setBeanName() in the execution_table.

According to variable_tracker, what is the state of the Bean Instance after properties are set?

A Properties Set

B Created

C Destroyed

D Initialized

💡 Hint

Look at the 'After Properties Set' column for 'Bean Instance' in variable_tracker.

If the custom init-method is removed, which step in the execution_table would be skipped?

A Step 7

B Step 11

C Step 8

D Step 4

💡 Hint

Step 8 shows the custom init-method call in the execution_table.

Concept Snapshot

Bean lifecycle in Spring Boot:
1. Bean is instantiated and properties set.
2. Awareness interfaces inject context (name, factory).
3. Initialization callbacks run (afterPropertiesSet, custom init).
4. Bean is ready for use.
5. On shutdown, destroy callbacks run (destroy, custom destroy).
This ensures beans are properly prepared and cleaned up.

Full Transcript

The Spring Boot bean lifecycle starts when the container loads the bean definition. Spring creates the bean instance and sets its properties. Then, it calls awareness methods like setBeanName and setBeanFactory to inject context. Before the bean is ready, Spring runs initialization callbacks such as afterPropertiesSet and any custom init-method. After initialization, the bean is ready for use. When the container shuts down, Spring calls destroy methods to clean up resources. This lifecycle ensures beans are properly created, initialized, and destroyed in an orderly way.