24.7.4 @ConfigurationProperties Validation
Spring Boot will attempt to validate external configuration, by default using JSR-303 (if it is on the classpath).
You can simply add JSR-303 javax.validationconstraint annotations to your @ConfigurationProperties class:
@ConfigurationProperties(prefix="foo")
public class FooProperties {
@NotNull
private InetAddress remoteAddress;
// ... getters and setters
}
In order to validate values of nested properties, you must annotate the associated field as @Valid to trigger its validation. For example, building upon the aboveFooProperties example:
@ConfigurationProperties(prefix="connection")
public class FooProperties {
@NotNull
private InetAddress remoteAddress;
@Valid
private final Security security = new Security();
// ... getters and setters
public static class Security {
@NotEmpty
public String username;
// ... getters and setters
}
}
You can also add a custom Spring Validator by creating a bean definition called configurationPropertiesValidator. The @Bean method should be declared static. The configuration properties validator is created very early in the application’s lifecycle and declaring the @Bean method as static allows the bean to be created without having to instantiate the @Configuration class. This avoids any problems that may be caused by early instantiation. There is a property validation sample so you can see how to set things up.