Learn to retrieve and access the application startup arguments in @Component annotated classes and @Bean annotated methods in a Spring boot application using org.springframework.boot.ApplicationArguments class.
For Spring Boot 2.x, we can pass the arguments using -Dspring-boot.run.arguments:
mvn spring-boot:run -Dspring-boot.run.arguments=--customArgument=customEach word after the run command is an argument. The arguments that start with
'-'are option argument; and others are non-option arguments.
1. Spring ApplicationArguments as Constructor Injection
The constructor injection is a fairly simple way to gain access to application arguments. Here we need to use the command line arguments in the constructor itself.
@Component
public class ArgsComponent
{
private List<String> customArgument;
@Autowired
public ArgsComponent(ApplicationArguments args)
{
this.customArgument = args.getOptionValues("customArgument");
}
}2. @Autowired ApplicationArguments
If we do not specifically require arguments in the constructor, autowiring is the cleaner way to inject ApplicationArguments class in any Spring component or configuration class.
@Component
public class ArgsComponent
{
private List<String> customArgument;
@Autowired
private ApplicationArguments args;
public ArgsComponent()
{
this.customArgument = args.getOptionValues("customArgument");
}
}3. Using @Value Annotation
The @Value annotation is generally used to inject the values configured in the application.properties. We can use @Value in inject the command line arguments as well.
It also means that command-line arguments can override the application properties.
@Component
public class ArgsComponent
{
@Value("${customArgument}")
private String customArgument;
//...
}Drop me your questions related to this spring boot command line arguments example to demonstrate access command line arguments while executing spring boot jar application.
Happy Learning !!
Diff b/w @component and @bean?
@Component is a general-purpose class-level annotation that marks a class as eligible for Spring’s auto-detection and auto-configuration mechanisms. Spring will automatically detect and register it as a bean.
@Bean is a method-level annotation used within a @Configuration classes where the return value of that method is registered as a bean in the Spring IoC container.
You can insert the URL and endpoint directly in the constructor like this
private final UriTemplate orderSearchUrl; public OrderServiceProxy(@Value("${service.order.baseUrl}${service.order.searchEndPoint}") UriTemplate orderSearchUrl) { this.orderSearchUrl = orderSearchUrl; }service: order: baseUrl: http://order-service.com/v1 searchEndPoint: /orderId/{orderId}/cafeId/{cafeId}