SpringBoot101: Configurations
Tags: programming, springboot, beginners, webdev
Published: 2023-11-18 15:14:45

Configuring applications can be both exciting and challenging for developers. In this blog post, we'll dive into the intricacies of Spring configurations, exploring practical techniques like the @Value annotation, leveraging Spring Boot's features, YAML files, and more.

## Using @Value Annotation:

Injecting properties with the @Value annotation is a common practice. It's a concise way to pull in configuration values directly into our beans.
java

```
@Value("${jdbc.url}")
private String jdbcUrl;
```

## Properties with Spring Boot:
Spring Boot simplifies configuration, offering conventions that reduce the need for explicit setup. The application.properties file is automatically detected, sparing us from manual registration. Runtime configurations are flexible, allowing alternative files or locations.

```
java -jar app.jar --spring.config.location=classpath:/another-location.properties

```
## Environment-Specific and Test-Specific Properties:
Spring Boot provides easy ways to handle environment-specific configurations and tests. Special files like application-environment.properties and @TestPropertySource annotations give granular control.

```
@TestPropertySource(properties = {"foo=bar"})
public class PropertyInjectionUnitTest {
    // Test implementation
}
```

## Hierarchical Properties:
Managing grouped properties is streamlined with the @ConfigurationProperties annotation. It's a developer-friendly way to structure and organize configurations.

```
@ConfigurationProperties(prefix = "database")
public class Database {
    // Fields and getters/setters
}
```

## YAML Files:
YAML files are a developer's delight for structured configuration. While they handle nested properties elegantly, keep in mind they don't play nice with the @PropertySource annotation.
yaml

```
database:
  url: jdbc:postgresql:/localhost:5432/instance
  username: foo
  password: bar
secret: foo
```

## Importing Additional Configuration Files:
Spring Boot 2.4.0 introduces the spring.config.import property, enabling easy inclusion of additional configuration files. It's a powerful tool for handling diverse configuration sources.

```
spring.config.import=classpath:additional-application.properties,
  classpath:additional-application[.yml],
  optional:file:./external.properties,
  classpath:additional-application-properties/
```

## Properties From Command Line Arguments and Environment Variables:
Directly passing properties through the command line or environment variables is a developer's go-to for quick adjustments.

```
java -jar app.jar --property="value"
```

```
export name=value
java -jar app.jar
```
## Randomization of Property Values:
Injecting a bit of randomness into property values is possible with Spring Boot's RandomValuePropertySource. It's a playful feature for scenarios where deterministic values aren't necessary.

```
random.number=${random.int}
random.long=${random.long}
random.uuid=${random.uuid}
```

## Additional Types of Property Sources:
Spring Boot supports a plethora of property sources, each with its own strengths. Developers looking for specific behavior should refer to the official documentation for a comprehensive understanding.

Configuration Using Raw Beans — the PropertySourcesPlaceholderConfigurer:
For developers who want complete control, manually defining the property configuration bean with PropertySourcesPlaceholderConfigurer provides flexibility.

```
@Bean
public static PropertySourcesPlaceholderConfigurer properties(){
    // Bean configuration details
}
```


## Conclusion

Configuring properties is a daily task for developers, and mastering Spring's tools makes it a smoother experience. Armed with techniques like @Value, Spring Boot conventions, and YAML files, developers can confidently handle diverse configurations. So, developer comrades, venture forth with Spring configurations and conquer your application's setup challenges!

Keep Coding!!!!