Spring console application configured using annotations

Question

I want to create spring console application (running from command line with maven for example: mvn exec:java -Dexec.mainClass=\"package.MainClass\").

Is this application

Answer 1

The Spring Reference suggests using ClassPathXmlApplicationContext in the main method to create the application context, then calling the getBean method to get an initial reference to a bean from the application context. After writing this same code a few times, you wind up refactoring the boilerplate into this utility class:

/**
 * Bootstraps Spring-managed beans into an application. How to use:
 * 

 * 
Create application context XML configuration files and put them where
 * they can be loaded as class path resources. The configuration must include
 * the {@code } element to enable annotation-based
 * configuration, or the {@code }
 * element to also detect bean definitions from annotated classes.
 * 
Create a "main" class that will receive references to Spring-managed
 * beans. Add the {@code @Autowired} annotation to any properties you want to be
 * injected with beans from the application context.
 * 
In your application {@code main} method, create an
 * {@link ApplicationContextLoader} instance, and call the {@link #load} method
 * with the "main" object and the configuration file locations as parameters.
 * 
 */
public class ApplicationContextLoader {

    protected ConfigurableApplicationContext applicationContext;

    public ConfigurableApplicationContext getApplicationContext() {
        return applicationContext;
    }

    /**
     * Loads application context. Override this method to change how the
     * application context is loaded.
     * 
     * @param configLocations
     *            configuration file locations
     */
    protected void loadApplicationContext(String... configLocations) {
        applicationContext = new ClassPathXmlApplicationContext(
                configLocations);
        applicationContext.registerShutdownHook();
    }

    /**
     * Injects dependencies into the object. Override this method if you need
     * full control over how dependencies are injected.
     * 
     * @param main
     *            object to inject dependencies into
     */
    protected void injectDependencies(Object main) {
        getApplicationContext().getBeanFactory().autowireBeanProperties(
                main, AutowireCapableBeanFactory.AUTOWIRE_NO, false);
    }

    /**
     * Loads application context, then injects dependencies into the object.
     * 
     * @param main
     *            object to inject dependencies into
     * @param configLocations
     *            configuration file locations
     */
    public void load(Object main, String... configLocations) {
        loadApplicationContext(configLocations);
        injectDependencies(main);
    }
}

Call the load method in your application main method. Notice that the Main class is not a Spring-created bean, and yet you can inject one of its properties with a bean from the application context.

public class Main {
    @Autowired
    private SampleService sampleService;

    public static void main(String[] args) {
        Main main = new Main();
        new ApplicationContextLoader().load(main, "applicationContext.xml");
        main.sampleService.getHelloWorld();
    }
}