java 45 lines · 7 steps

A custom @Conditional feature flag in Spring

A Spring Condition that toggles bean registration based on a feature flag property and active profiles.

Explained by highlit

Spring Intermediate conditional beans feature flags annotations environment profiles

1package com.example.config.condition;
2 
3import org.springframework.context.annotation.Condition;
4import org.springframework.context.annotation.ConditionContext;
5import org.springframework.core.env.Environment;
6import org.springframework.core.type.AnnotatedTypeMetadata;
7 
8import java.util.Map;
9 
10public class OnFeatureFlagCondition implements Condition {
11 
12    @Override
13    public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
14        Map<String, Object> attributes =
15                metadata.getAnnotationAttributes(ConditionalOnFeature.class.getName());
16        if (attributes == null) {
17            return false;
18        }
19 
20        String feature = (String) attributes.get("value");
21        boolean expected = (boolean) attributes.get("enabledByDefault");
22 
23        Environment env = context.getEnvironment();
24        String property = "features." + feature + ".enabled";
25        boolean enabled = env.getProperty(property, Boolean.class, expected);
26 
27        String[] requiredProfiles = (String[]) attributes.get("activeProfiles");
28        if (requiredProfiles.length > 0 && !anyProfileActive(env, requiredProfiles)) {
29            return false;
30        }
31 
32        return enabled;
33    }
34 
35    private boolean anyProfileActive(Environment env, String[] profiles) {
36        for (String profile : profiles) {
37            for (String active : env.getActiveProfiles()) {
38                if (active.equalsIgnoreCase(profile)) {
39                    return true;
40                }
41            }
42        }
43        return false;
44    }
45}

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STEP 01

Walkthrough

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Three takeaways

1Implementing Condition lets you gate bean registration on arbitrary runtime logic beyond Spring's built-in conditions.
2Reading annotation attributes via AnnotatedTypeMetadata connects a custom annotation to its evaluation logic.
3Combining a property lookup with a profile check produces flexible, layered activation rules.

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