🚀 Auto-Configuration in Spring Boot ⚡

👉 Spring Boot AutoConfiguration = less manual config + faster development.

When we call SpringApplication.run(..,..) from our main class (which also serves as the Configuration class) — a lot happens behind the scenes 👀

One of the most powerful operations is AutoConfiguration — where Spring Boot automatically configures beans based on the starters/jars you’ve added to your classpath.

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Here’s how it actually works 👇

🧩 AutoConfiguration Process (Step by Step)

🔍 The IoC container scans all JARs in the classpath to find a file named spring.factories.
📂 It locates this file in multiple JARs.

🧠 Inside each, it looks for the key:
org.springframework.boot.autoconfigure.EnableAutoConfiguration
⚙️ In the spring-boot-autoconfigure-.jar, it collects all the values mapped to that key — which are pre-built configuration classes such as:

👇
org.springframework.boot.autoconfigure.EnableAutoConfiguration=/,
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration,
org.springframework.boot.autoconfigure.jdbc.JdbcTemplateAutoConfiguration,
org.springframework.boot.autoconfigure.jdbc.XADataSourceAutoConfiguration,
org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfig

🔁 Spring then processes each of these configuration classes (including their nested and imported @Configuration classes).
🧱 It executes all their @bean methods to create ready-to-use beans — like HikariDataSource, JdbcTemplate, etc.

That’s how Spring Boot gives you so much out-of-the-box power 🔥

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🛑 Can We Disable Specific AutoConfigurations?

✅ Absolutely.
Even if you’ve added certain starters, you can stop specific auto-configurations by using the exclude parameter in @SpringBootApplication:

Example 👇
@SpringBootApplication(exclude = { DataSourceAutoConfiguration.class,
JdbcTemplateAutoConfiguration.class })
public class BootProjRealtimeDiAutoConfigurationApplication {
// ...
...
}

💬 In short:
Spring Boot AutoConfiguration = less manual config + faster development.
And when you need control, Spring gives it back — effortlessly. 🙌