23.9 application exit application exit

Every SpringApplication Will be in JVM Register a close hook on , In order to ensure that ApplicationContext Close gracefully on exit . All standard Spring Lifecycle Callback ( for example DisposableBean Interface , perhaps @PreDestroy notes ) You can use .

Besides ,bean It can also be realized org.springframework.boot.ExitCodeGenerator SHI

And add resource files application.properties：

name: JavaChen

Application Start class

@SpringBootApplication
public class Springboot239Application implements CommandLineRunner {
   @Autowired
   private HelloWorldService helloWorldService;
   public static void main(String[] args) {
      SpringApplication.run(Springboot239Application.class, args);
   }
   @Override
   public void run(String... args) {
      System.out.println(this.helloWorldService.getMessage());
      if (args.length > 0 && args[0].equals("exitcode")) {
         throw new ExitException();
      }
   }
}

If some CommandLineRunner beans Defined must be called in a specific order , You can achieve extra org.springframework.core.Ordered Interface or use @Order annotation .

utilize command-line runner This characteristic of , Then cooperate with dependency injection , You can first introduce some dependencies after the application starts bean, for example data source、rpc Services or other modules , The initialization of these objects can be placed in run In the method . however , It should be noted that , stay run Method, once any exception is encountered , Will make the application stop running , Therefore, it is best to make use of try/catch Statement processing may encounter exceptions .

Every SpringApplication In order to ensure ApplicationContext Gracefully closed , Will register a JVM Of shutdown hook . All standard Spring Lifecycle Callback （ such as ,DisposableBean Interface or @PreDestroy annotation ） Can use .

Besides , If beans Want to return a specific exit code at the end of the application , Can achieve org.springframework.boot.ExitCodeGenerator Interface , For example, in the example above ExitException Exception class ：

public class ExitException extends RuntimeException implements ExitCodeGenerator {
    @Override
    public int getExitCode() {
        return 10;
    }
}

@Component
public class HelloWorldService {
    @Value("${name:World}")
    private String name;

    public String getMessage() {
        return "Hello " + this.name;
    https://github.com/csg103/springboot23-9}
}

Source code address   https://github.com/csg103/springboot23-9