In Spring Boot, the @ConfigurationProperties annotation is used to bind external configuration properties to a JavaBean. This annotation is particularly useful when you want to map properties defined in external configuration files (like application.properties or application.yml) to a Java class. It simplifies the process of reading configuration values and injecting them into your application
Here's a basic example to illustrate how to use @ConfigurationProperties in a Spring Boot application:
Step 1: Create a configuration class
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
@Getter
@Setter
@ConfigurationProperties(prefix = "example")
public class MyAppProperties {
private String appName;
private String version;
private int maxAllowedUsers;
}
In this example, the @ConfigurationProperties annotation is used with the prefix attribute to specify the common prefix for all properties in the configuration file that will be bound to this class.
Step 2: Configure your application.properties or application.yml file
example.appName=MySpringApp
example.version=1.0
example.maxAllowedUsers=100
Step 3: Use the configuration properties in your application
@SpringBootApplication
public class MySpringBootApplication implements CommandLineRunner {
@Autowired
private MyAppProperties myAppProperties;
public static void main(String[] args) {
SpringApplication.run(MySpringBootApplication.class, args);
}
@Override
public void run(String... args) throws Exception {
System.out.println("Application Name: " + myAppProperties.getAppName());
System.out.println("Version: " + myAppProperties.getVersion());
System.out.println("Max Allowed Users: " + myAppProperties.getMaxAllowedUsers());
}
}
In this example, the properties defined in application.properties under the example prefix will be automatically mapped to the corresponding fields in the MyAppProperties class.