How to Configure Multiple Instances of @ConfigurationProperties with the Same Class in Spring?

How can I use multiple @ConfigurationProperties for the same class in Spring?

@ConfigurationProperties(prefix="example")
public class ExampleProperties {
    private String property1;
    private String property2;
    // getters and setters
}

Spring's @ConfigurationProperties annotation allows you to bind external configurations to Java objects. However, if you need to create multiple instances of the same properties class, you may face challenges in managing these instances effectively. This guide explains how to handle multiple instances of @ConfigurationProperties annotated classes within a Spring application, ensuring they remain decoupled yet functional.

@Configuration
public class AppConfig {
    @Bean
    @ConfigurationProperties(prefix = "example1")
    public ExampleProperties exampleProperties1() {
        return new ExampleProperties();
    }
    
    @Bean
    @ConfigurationProperties(prefix = "example2")
    public ExampleProperties exampleProperties2() {
        return new ExampleProperties();
    }
}

Causes

• Default behavior in Spring does not allow multiple beans with the same type, leading to conflicts.
• Configuration properties are often loaded into a single bean, causing data overwrites.

Solutions

• Use different `prefixes` for each instance of @ConfigurationProperties in your configuration files or classes.
• Use the `@Bean` annotation together with the `@ConfigurationProperties` annotation to define the instances explicitly.
• Create a custom configuration class where you programmatically register multiple @ConfigurationProperties instances with distinct qualifiers.

Mistake: Using the same prefix for multiple instances, which leads to binding errors.

Solution: Ensure all @ConfigurationProperties instances have unique prefixes.

Mistake: Failing to annotate the configuration class with @EnableConfigurationProperties.

Solution: The configuration class should be annotated properly to enable loading of configuration properties.