what actually excludeFilters does in #ComponentScan - spring

Question

I have created a simple spring application to test excludeFilters in #ComponentScan annotation.
TestConfig.java
package com.example.config;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.FilterType;
import org.springframework.stereotype.Controller;
#Configuration
#ComponentScan(
excludeFilters = #ComponentScan.Filter(
type = FilterType.REGEX,
pattern = {"com.example.Demo"}
)
)
public class TestConfig {
}
Demo.java
package com.example;
import org.springframework.stereotype.Component;
#Component
public class Demo {
}
Main class ExcludeFilterTest.java
public class ExcludeFilterTest {
public static void main(String[] args) {
ApplicationContext applicationContext = new AnnotationConfigApplicationContext("com.example");
}
}
when running the application I can see the Demo class is getting identified as a candidate component class and also instance is getting created.
here are the logs
12:05:34.151 [main] DEBUG org.springframework.context.annotation.ClassPathBeanDefinitionScanner - Identified candidate component class: file [/Users/sk/learning-development/interview/logging_test/target/classes/com/example/Demo.class]
12:05:34.160 [main] DEBUG org.springframework.context.annotation.ClassPathBeanDefinitionScanner - Identified candidate component class: file [/Users/sk/learning-development/interview/logging_test/target/classes/com/example/config/TestConfig.class]
12:05:34.172 [main] DEBUG org.springframework.context.annotation.AnnotationConfigApplicationContext - Refreshing org.springframework.context.annotation.AnnotationConfigApplicationContext#687080dc
12:05:34.188 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalConfigurationAnnotationProcessor'
12:05:34.275 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerProcessor'
12:05:34.277 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.event.internalEventListenerFactory'
12:05:34.278 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'org.springframework.context.annotation.internalAutowiredAnnotationProcessor'
12:05:34.282 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'demo'
12:05:34.298 [main] DEBUG org.springframework.beans.factory.support.DefaultListableBeanFactory - Creating shared instance of singleton bean 'testConfig'
Process finished with exit code 0
why the Demo class instance is getting created?

Answer 1

Try this instead.
public class ExcludeFilterTest {
public static void main(String[] args) {
ApplicationContext applicationContext = new AnnotationConfigApplicationContext(com.example.config.TestConfig.class);
}
}