Java SDK

The можно Java SDK provides local evaluation of feature flags on the JVM. Compatible with JDK 17+, supports synchronous evaluation, and integrates with Spring Boot via auto-configuration.

Installation

Gradle (Kotlin DSL)

repositories {
    mavenCentral()
}

dependencies {
    implementation("dev.mozhno:mozhno-client-java:1.1.1")
}

Gradle (Groovy DSL)

repositories {
    mavenCentral()
}

dependencies {
    implementation 'dev.mozhno:mozhno-client-java:1.1.1'
}

Tip: Check the GitHub releases page for the latest version.

Configuration

The SDK uses a builder pattern for client construction. Create a single client instance and reuse it across your application:

import dev.mozhno.sdk.MozhnoClient;
import dev.mozhno.sdk.MozhnoConfig;
import dev.mozhno.sdk.MozhnoContext;
import dev.mozhno.sdk.DefaultMozhnoClient;

MozhnoConfig config = MozhnoConfig.builder()
    .appName("my-app")
    .instanceId("instance-1")
    .mozhnoUrl("https://mozhno.example.com")
    .apiKey("<api-key>")
    .fetchTogglesInterval(15)
    .sendMetricsInterval(60)
    .environment("production")
    .build();

MozhnoClient client = new DefaultMozhnoClient(config);
client.start();

Builder Options

Method	Type	Default	Description
appName(String)	String	Required	Your application identifier
instanceId(String)	String	Required	Unique instance identifier
mozhnoUrl(String)	String	Required	Base URL of your можно instance
apiKey(String)	String	Required	API key for the target environment
fetchTogglesInterval(int)	int	15 sec	Polling interval
sendMetricsInterval(int)	int	60 sec	Metrics reporting interval
environment(String)	String	null	Environment name
disableMetrics(boolean)	boolean	false	Disable metrics reporting
synchronousFetchOnInitialisation(boolean)	boolean	false	Block on initial flag fetch
stickyAnonId(boolean)	boolean	true	Auto-generate a stable anonymous ID for rollout bucketing
contextProvider(MozhnoContextProvider)	—	null	Custom context provider

Spring Boot Auto-Configuration

The SDK provides auto-configuration via MozhnoAutoConfiguration. Configure via application.yml:

mozhno:
  url: https://mozhno.example.com
  api-key: <api-key>
  app-name: my-app
  instance-id: ${random.uuid}
  environment: production
  fetch-toggles-interval: 15
  send-metrics-interval: 60
  sticky-anon-id: true

The client is automatically created and available as a Spring bean:

@Service
public class CheckoutService {

    private final MozhnoClient mozhnoClient;

    public CheckoutService(MozhnoClient mozhnoClient) {
        this.mozhnoClient = mozhnoClient;
    }

    public boolean isNewCheckoutEnabled(String userId) {
        MozhnoContext context = MozhnoContext.builder()
            .userId(userId)
            .addProperty("country", "DE")
            .build();
        return mozhnoClient.isEnabled("checkout_v2", context);
    }
}

MozhnoContext

A builder-based context object for providing attributes at evaluation time.

import dev.mozhno.sdk.MozhnoContext;

MozhnoContext context = MozhnoContext.builder()
    .userId("user-12345")
    .sessionId("session-abc")
    .addProperty("country", "DE")
    .addProperty("plan", "enterprise")
    .addProperty("appVersion", "2.4.1")
    .build();

All attribute values are strings. For numeric comparisons, set contextType: number in your targeting rules.

Anonymous Users and Rollout

For percentage rollout, the SDK uses userId, then sessionId, as the bucketing identifier. When neither is present in the context, the client auto-generates a stable anonymousId (a random UUID created at client startup) and uses it instead — anonymous traffic is bucketed uniformly and stays stable for each application instance. To disable this behavior, use stickyAnonId(false) (or mozhno.sticky-anon-id: false in Spring); in that case all anonymous requests without an identifier land in a single bucket and the SDK logs a warning. See the rollout guide for upgrade behavior details.

Method	Description
userId(String)	User ID (used for percentage rollout hashing)
sessionId(String)	Session ID (fallback for hashing)
addProperty(String key, String value)	Arbitrary attribute

Next Steps

• SDK Overview — Architecture and evaluation model.
• JavaScript SDK — For Node.js and browser applications.
• API Overview — auth and base concepts