Custom auto-configuration in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to mark a class as a Spring Boot auto-configuration.

Spring Boot

@[1]
public class MyAutoConfiguration {
}

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AEnableAutoConfiguration

BComponent

CConfiguration

DSpringBootApplication

Attempts:

3 left

💡 Hint

Common Mistakes

Using @Component instead of @Configuration

Using @EnableAutoConfiguration on the class directly

The @Configuration annotation marks the class as a source of bean definitions for Spring.

2fill in blank

medium

Complete the code to conditionally enable the auto-configuration only if a bean of type DataSource is missing.

Spring Boot

@ConditionalOnMissingBean([1].class)
public class MyAutoConfiguration {
}

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ADataSource

BRestTemplate

CJdbcTemplate

DEntityManager

Attempts:

3 left

💡 Hint

Common Mistakes

Using JdbcTemplate instead of DataSource

Using EntityManager which is JPA specific

The @ConditionalOnMissingBean(DataSource.class) annotation ensures the configuration applies only if no DataSource bean exists.

3fill in blank

hard

Fix the error in the code to properly register the auto-configuration class in Spring Boot.

Spring Boot

META-INF/spring.factories:
org.springframework.boot.autoconfigure.EnableAutoConfiguration=[1]

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Acom.example.MyAutoConfiguration.class

Bcom.example.MyAutoConfiguration.java

Corg.springframework.boot.autoconfigure.EnableAutoConfiguration

Dcom.example.MyAutoConfiguration

Attempts:

3 left

💡 Hint

Common Mistakes

Adding '.class' suffix

Using the annotation name instead of class name

The spring.factories file must list the fully qualified class name without '.class' or file extensions.

4fill in blank

hard

Fill both blanks to create a bean method that returns a RestTemplate only if no other RestTemplate bean exists.

Spring Boot

@Bean
@ConditionalOnMissingBean([1].class)
public [2] restTemplate() {
    return new RestTemplate();
}

Drag options to blanks, or click blank then click option'

ARestTemplate

BDataSource

DJdbcTemplate

Attempts:

3 left

💡 Hint

Common Mistakes

Using DataSource in condition but returning RestTemplate

Mismatching return type and condition class

The method returns a RestTemplate bean and is conditional on missing RestTemplate beans.

5fill in blank

hard

Fill all three blanks to create a conditional auto-configuration that loads only if property 'app.feature.enabled' is true and a bean of type FeatureService is missing.

Spring Boot

@ConditionalOnProperty(name = "app.feature.enabled", havingValue = "[1]")
@ConditionalOnMissingBean([2].class)
@Configuration
public class FeatureAutoConfiguration {
    @Bean
    public [3] featureService() {
        return new FeatureService();
    }
}

Drag options to blanks, or click blank then click option'

Atrue

BFeatureService

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'false' as property value

Mismatching bean type in condition and method return

The property must be 'true' to enable the config, and the bean type must be FeatureService for both condition and return type.