Spring Boot Annotation @SpringBootApplication usage details

@SpringBootApplication annotation

1. Introduction

@SpringBootApplicationIt is an annotation provided by Spring Boot, which is usually used on the startup class (main class). It is a combination of three annotations:
1.@Configuration
Indicates that this class is a configuration class, equivalent to an XML configuration file.

2.@EnableAutoConfiguration
Tell Spring Boot to start the automatic configuration function and automatically configure Spring applications based on dependencies, configurations, etc. under the classpath.

3.@ComponentScan
Start component scanning, scan the package and subpackages of the current class by default, and inject classes marked with annotations such as @Component, @Service, @Repository, @Controller, etc. into the Spring container.

2. Use

1. Specify the package to scan

By default,@SpringBootApplicationIt will recursively scan all subpackage components from the package it is located (e.g.@Component、@Service、@Repository、@Controller、@Configurationwait).

If there are some components in your project that are not@SpringBootApplicationIn the sub-package of the package, you need to set it manuallyscanBasePackagesTo specify the package path to scan.
Examples are as follows:

@SpringBootApplication(scanBasePackages = {"", ""})
public class MyApplication {
    public static void main(String[] args) {
        (, args);
    }
}

Use scenarios

• Your startup class MyApplication is not in the package, such as it is in , while the system module and infrastructure module are in and , respectively. In this case, the default scan will not overwrite and you need to specify it manuallyscanBasePackages。
• You only want to scan some packages, not the entire project's package. This can reduce the scanning overhead during startup and improve performance.

Replenish
Use ${} to inject configuration property values ​​as follows:

@SpringBootApplication(scanBasePackages = {"${-package}.server", "${-package}.module"})
public class MyApplication {
    public static void main(String[] args) {
        (, args);
    }
}

The .yaml file is as follows:

demo:
  info:
    base-package: 

Note:Custom starter annotations with @AutoConfiguration without having to put its path into the scan path.

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