Spring Boot 2.1 bean override 与 Primary

Spring Boot是一个开源的Java框架，用于开发和构建独立的、基于Spring的应用程序。它简化了Spring应用程序的配置和部署过程，提供了一种快速、方便的方式来创建可独立运行的、生产级别的Spring应用程序。

java
@Configuration
public class AppConfig {
    @Bean
    public GreetingService primaryGreetingService() {
        return new PrimaryGreetingService();
    }
    @Bean
    @Primary
    public GreetingService secondaryGreetingService() {
        return new SecondaryGreetingService();
    }
}
public interface GreetingService {
    String greet();
}
public class PrimaryGreetingService implements GreetingService {
    @Override
    public String greet() {
        return "Hello from primary greeting service!";
    }
}
public class SecondaryGreetingService implements GreetingService {
    @Override
    public String greet() {
        return "Hello from secondary greeting service!";
    }
}
@RestController
public class GreetingController {
    private final GreetingService greetingService;
    public GreetingController(GreetingService greetingService) {
        this.greetingService = greetingService;
    }
    @GetMapping("/greet")
    public String greet() {
        return greetingService.greet();
    }
}

java
@Configuration
public class AppConfig {
    @Bean
    public GreetingService primaryGreetingService() {
        return new PrimaryGreetingService();
    }
    @Bean
    public GreetingService secondaryGreetingService() {
        return new SecondaryGreetingService();
    }
    @Bean
    public GreetingService overriddenGreetingService() {
        return new OverriddenGreetingService();
    }
}
public class OverriddenGreetingService implements GreetingService {
    @Override
    public String greet() {
        return "Hello from overridden greeting service!";
    }
}