Micronaut Facts 1

@Around

1. The @Around annotation is used in Micronaut to intercept method calls.
2. It allows you to execute code before and after the method call.
3. The @Around annotation is part of the AOP (Aspect-Oriented Programming) support in Micronaut.
4. It’s a way to separate cross-cutting concerns from the main business logic of your application.
5. The @Around annotation is used to create advice that can be applied to multiple methods in your application.
6. It’s a powerful feature that allows you to add behavior to your methods without modifying their code directly.
7. The @Around annotation is often used for logging, security, transaction management, and other cross-cutting concerns.
8. It’s a flexible and powerful way to enhance the behavior of your methods without changing their implementation.

// example of @Around annotation with import
import io.micronaut.aop.Around;
import io.micronaut.aop.InvocationContext;
import org.slf4j.Logger;

@Around
public Object log(InvocationContext context) throws Exception {
    // code to execute before the method call
    log.info("Before method call: {}", context.getMethodName());

    // execute the method
    Object result = context.proceed();

    // code to execute after the method call
    log.info("After method call: {}", context.getMethodName());

    return result;
}

---

@Singleton

1. The @Singleton annotation is used in Micronaut to create a singleton bean.
2. It’s a way to create a single instance of a bean that is shared across your application.
3. The @Singleton annotation is used to annotate classes that you want to be managed as singletons by the Micronaut IoC container.
4. It’s a convenient way to share state and behavior across your application without having to manage the lifecycle of the bean yourself.
5. The @Singleton annotation is often used for services, repositories, and other stateful components that need to be shared across multiple parts of your application.
6. It’s a powerful feature that allows you to create and manage singleton beans with minimal configuration.
7. The @Singleton annotation is a key part of the dependency injection support in Micronaut.
8. It’s a flexible and easy way to manage the lifecycle of your beans and share them across your application.

// example of @Singleton annotation with import
import javax.inject.Singleton;

@Singleton
public class MyService {
    public void doSomething() {
        // code to do something
    }
}

// example of @Singleton annotation with constructor injection
@Singleton
public class MyService {
    private final MyRepository repository;

    public MyService(MyRepository repository) {
        this.repository = repository;
    }

    public void doSomething() {
        // code to do something
    }
}

// example of @Singleton annotation with field injection
@Singleton
public class MyService {
    @Inject
    private MyRepository repository;

    public void doSomething() {
        // code to do something
    }
}

// example of @Singleton annotation with method injection
@Singleton
public class MyService {
    private MyRepository repository;

    @Inject
    public void setRepository(MyRepository repository) {
        this.repository = repository;
    }

    public void doSomething() {
        // code to do something
    }
}

// example of @Singleton annotation with constructor injection and @Value annotation
@Singleton
public class MyService {
    private final String message;

    public MyService(@Value("${my.message}") String message) {
        this.message = message;
    }

    public void doSomething() {
        // code to do something
    }
}

// example of @Singleton annotation with constructor injection and @ConfigurationProperties annotation
@Singleton
@ConfigurationProperties("my")
public class MyService {
    private final String message;

    public MyService(@Value("${message}") String message) {
        this.message = message;
    }

    public void doSomething() {
        // code to do something
    }
}

// example of @Singleton annotation with constructor injection and @Property annotation
@Singleton
public class MyService {
    private final String message;

    public MyService(@Property(name = "my.message") String message) {
        this.message = message;
    }

    public void doSomething() {
        // code to do something
    }
}

---

@Inject

1. The @Inject annotation is used in Micronaut to inject dependencies into your beans.
2. It’s a way to declare that a field, constructor parameter, or setter method should be injected by the Micronaut IoC container.
3. The @Inject annotation is used to annotate fields, constructors, and methods that you want to be injected by Micronaut.
4. It’s a convenient way to declare your dependencies and let Micronaut manage their lifecycle for you.
5. The @Inject annotation is often used for constructor injection, field injection, and method injection.
6. It’s a powerful feature that allows you to inject dependencies wherever you need them in your beans.
7. The @Inject annotation is a key part of the dependency injection support in Micronaut.

// example of @Inject annotation with constructor injection
import javax.inject.Inject;

public class MyService {
    private final MyRepository repository;

    @Inject
    public MyService(MyRepository repository) {
        this.repository = repository;
    }

    public void doSomething() {
        // code to do something
    }
}

// example of @Inject annotation with field injection
public class MyService {
    @Inject
    private MyRepository repository;

    public void doSomething() {
        // code to do something
    }
}

// example of @Inject annotation with method injection
public class MyService {
    private MyRepository repository;

    @Inject
    public void setRepository(MyRepository repository) {
        this.repository = repository;
    }

    public void doSomething() {
        // code to do something
    }
}

// example of @Inject annotation with constructor injection and @Value annotation
import io.micronaut.context.annotation.Value;

public class MyService {
    private final String message;

    @Inject
    public MyService(@Value("${my.message}") String message) {
        this.message = message;
    }

    public void doSomething() {
        // code to do something
    }
}

// example of @Inject annotation with constructor injection and @ConfigurationProperties annotation
import io.micronaut.context.annotation.ConfigurationProperties;

public class MyService {
    private final String message;

    @Inject
    public MyService(@Value("${message}") String message) {
        this.message = message;
    }

    public void doSomething() {
        // code to do something
    }
}

// example of @Inject annotation with constructor injection and @Property annotation
import io.micronaut.context.annotation.Property;

public class MyService {
    private final String message;

    @Inject
    public MyService(@Property(name = "my.message") String message) {
        this.message = message;
    }

    public void doSomething() {
        // code to do something
    }
}


// example of @Inject annotation with field injection and @Value annotation
import io.micronaut.context.annotation.Value;

public class MyService {
    @Inject
    @Value("${my.message}")
    private String message;

    public void doSomething() {
        // code to do something
    }
}

// example of @Inject annotation with field injection and @ConfigurationProperties annotation
import io.micronaut.context.annotation.ConfigurationProperties;

public class MyService {
    @Inject
    @ConfigurationProperties("my")
    private MyConfiguration configuration;

    public void doSomething() {
        // code to do something
    }
}

// example of @Inject annotation with field injection and @Property annotation
import io.micronaut.context.annotation.Property;

public class MyService {
    @Inject
    @Property(name = "my.message")
    private String message;

    public void doSomething() {
        // code to do something
    }
}

// example of @Inject annotation with method injection and @Value annotation
import io.micronaut.context.annotation.Value;

public class MyService {
    private String message;

    @Inject
    public void setMessage(@Value("${my.message}") String message) {
        this.message = message;
    }

    public void doSomething() {
        // code to do something
    }
}

// example of @Inject annotation with method injection and @ConfigurationProperties annotation
import io.micronaut.context.annotation.ConfigurationProperties;

public class MyService {
    private MyConfiguration configuration;

    @Inject
    public void setConfiguration(@ConfigurationProperties("my") MyConfiguration configuration) {
        this.configuration = configuration;
    }

    public void doSomething() {
        // code to do something
    }
}

---

@Value

1. The @Value annotation is used in Micronaut to inject configuration properties into your beans.
2. It’s a way to inject values from your application configuration into your beans.
3. The @Value annotation is used to annotate fields, constructors, and methods that you want to be injected with configuration properties.
4. It’s a convenient way to access configuration properties wherever you need them in your beans.
5. The @Value annotation is often used for injecting configuration properties into your beans.
6. It’s a powerful feature that allows you to configure your beans with external properties.
7. The @Value annotation is a key part of the configuration support in Micronaut.

// example of @Value annotation with field injection
import io.micronaut.context.annotation.Value;

public class MyService {
    @Value("${my.message}")
    private String message;

    public void doSomething() {
        // code to do something
    }
}

// example of @Value annotation with constructor injection
import io.micronaut.context.annotation.Value;

public class MyService {
    private final String message;

    public MyService(@Value("${my.message}") String message) {
        this.message = message;
    }

    public void doSomething() {
        // code to do something
    }
}

// example of @Value annotation with method injection
import io.micronaut.context.annotation.Value;

public class MyService {
    private String message;

    @Value("${my.message}")
    public void setMessage(String message) {
        this.message = message;
    }

    public void doSomething() {
        // code to do something
    }
}