CODEWITHSUNDEEP
javaspringspring-boot
Med Elgarnaoui
Med Elgarnaoui

Reputation: 1667

@Autowired an object from external Jar

I would like to autowire an object from an external JAR that I use it in my application:

@Autowired
PythonInterpreter interp;

I get this Exception :

Field interp in com.package.services.ServicesImpl required a bean of type 'org.python.util.PythonInterpreter' that could not be found.

Action:

Consider defining a bean of type 'org.python.util.PythonInterpreter' in your configuration.

I know that @ComponentScan will only work if the class is annotated with @Component.

Upvotes: 2

Views: 2477

Answers (2)

Ananthapadmanabhan
Ananthapadmanabhan

Reputation: 6216

Spring handles dependency injection through the @Autowired annotation.When a spring application is initially started it scan packages to discover beans. So all, classes that are annotated or meta-annotated with @Component will get picked up during component scan.

  • The beans discovered during component scan will then be added to the Spring application context.
  • We can use these beans from the spring application context using the @Autowired annotation

In your case,you are auto wiring the bean but spring cannot find a bean of type PythonInterpreter.class in it's context.That is why it is throwing that error.

The solution to your issue is to register the bean in Spring's application context in a configuration class.We usually register beans by annotation a class with the @Configuration (so that spring picks it up for component scan) annotation and the @Bean annotation as follows:

@Configuration
public class AppConfig {

    @Bean
    public MyService myService() {
        return new MyServiceImpl();
    }
}

or using xml based configuration as :

<beans>
    <bean id="myService" class="com.acme.services.MyServiceImpl"/>
</beans>

Upvotes: 1

GhostCat
GhostCat

Reputation: 140457

The point is: you have to tell Spring how to create an instance of that class.

See their example in their documentation:

@Configuration
public class AppConfig {

    @Bean
    public MyService myService() {
        return new MyServiceImpl();
    }
}

So, as the first comment correctly tells you: you need to define a method that somehow creates that object. Then you annotate that method as @Bean, and make sure that Spring finds it as @Configuration.

Upvotes: 6

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