appconfig spring

Innocent Iguana answered on February 18, 2024 Popularity 9/10 Helpfulness 3/10

answer appconfig spring

appconfig spring

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// WORKFLOW:
// 1. main method is the launcher of JVM. you need to bring in Spring IOC
// 2. Application context is the IOC container (instance of AnnotationConfigApplicationContext)
// 3. Application context needs a configuration class as dependency to know the Beans or "java instances" that will be used throughout the application (default : singletons)
// 4. The configuration class has bean methods that are responsible for creating the java objects

// application.properties (You can override with other VM or environment variables)
// example VM profile : -Dspring.profiles.active=dev
app.name=JohnDoe
app.greeting=Hello!!!
// ApplicationConfig.java
@Configuration
@PropertySource("classpath:application.properties")
public class ApplicationConfig {

    @Value("${app.greeting}")
    private String greeting;
    @Value("${app.name}")
    private String name;
    // Setting up the is24 SPEL variable to replace different profile beans
    @Value("#{new Boolean(environment['spring.profiles.active']!='dev')}")
    private boolean is24;

    @Autowired
    private GreetingService greetingService;
    @Autowired
    private TimeService timeService;
    
    // One Bean to replace multiple beans of different profiles with SPEL variable is24 
    @Bean
    public TimeService timeService(){
        return new TimeService(is24);
    }
//    @Bean
//    @Profile("!dev")
//    public TimeService timeService(){
//        return new TimeService(true);
//    }
//
//    @Bean
//    @Profile("dev") // another bean configuration for different profile
//    public TimeService timeService12(){
//        return new TimeService(false);
//    }

    @Bean
    public GreetingService greetingService(){
        return new GreetingService(greeting);
    }
    @Bean
    public OutputService outputService(){
        return new OutputService(greetingService, timeService, name);
    }
}
// Application.java
public class Application {
    public static void main(String[] args) throws Exception {
        ApplicationContext context = new AnnotationConfigApplicationContext(ApplicationConfig.class); // getting the configuration class
        OutputService outputService = context.getBean(OutputService.class); // retrieving bean using bean class name
      	// OutputService outputService = context.getBean("outputService"); // Alternative way of retrieving bean: using the bean method name inside configuration class

        for (int i=0;i<5;i++){
            outputService.generateOutput();
            Thread.sleep(5000);
        }
    }
}

Popularity 9/10 Helpfulness 3/10 Language java

Source: Grepper

Tags: app-config java spring

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Contributed on Feb 18 2024

Innocent Iguana

0 Answers Avg Quality 2/10

appconfig spring

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