Java 所需的单个bean，但在简单的spring引导应用程序中找到了2个

我不熟悉弹簧靴。因此，我正在开发一个简单的应用程序，其中我有两个服务

EnglishLanguageService

和

SpanishLanguageService

。最后，我想在应用程序运行时打印

Hello

和

Hola

，但我收到了错误

Parameter 0 of constructor in controller.ConstructorInjectedController required a single bean, but 2 were found:
    - profileEnglishLanguageService: defined in file [/Users/user/Downloads/depdency-injection-example/target/classes/services/EnglishLanguageService.class]
    - profileSpanishLanguageService: defined in file [/Users/user/Downloads/depdency-injection-example/target/classes/services/SpanishLanguageService.class]


Action:

Consider marking one of the beans as @Primary, updating the consumer to accept multiple beans, or using @Qualifier to identify the bean that should be consumed

我不确定我会错在哪里。我将把我的代码粘贴到下面

主要应用

@SpringBootApplication
@ComponentScan(basePackages= {"controller" , "services"})
public class DepdencyInjectionExampleApplication {

    public static void main(String[] args) {
        // returns application context
        ApplicationContext ctx = SpringApplication.run(DepdencyInjectionExampleApplication.class, args);

        System.out.println(ctx.getBean(PropertyInjectedController.class).getGreeting());
        System.out.println(ctx.getBean(ConstructorInjectedController.class).getGreetings());

    }

ConstructorInjectedController类

@Component
public class ConstructorInjectedController {

    private final GreetingService greetingService;

    public ConstructorInjectedController(GreetingService greetingService) {
        this.greetingService = greetingService;
    }

    public String getGreetings() {
        return greetingService.sayGreetings();
    }

PropertyInjectedControllerClass

@Controller
public class PropertyInjectedController {

    public GreetingService greetingService;

    public String getGreeting() {
        return greetingService.sayGreetings();
    }

}

迎宾服务接口

public interface GreetingService {

    String sayGreetings();

}

英语服务班

@Service
public class EnglishLanguageService implements GreetingService {

    private GreetingService greetingService;

    public EnglishLanguageService(@Qualifier("english")
                                                 GreetingService greetingService){
        this.greetingService = greetingService;
    }

    @Override
    public String sayGreetings() {
        return greetingService.sayGreetings();
    }

英语服务

@Profile("english")
public class EnglishServiceImpl implements GreetingService {
    @Override
    public String sayGreetings() {
        return "Hello";
    }

@Profile("spanish")
public class SpanishServiceImpl implements GreetingService {
    @Override
    public String sayGreetings() {
        return "Hola";
    }
}

西班牙语服务

@Service
public class SpanishLanguageService implements GreetingService {

    private GreetingService greetingService;

    public SpanishLanguageService(@Qualifier("spanish")
                                                 GreetingService greetingService){
        this.greetingService = greetingService;
    }
    @Override
    public String sayGreetings() {
        return greetingService.sayGreetings();
    }

西班牙语服务impl

@Profile("english")
public class EnglishServiceImpl implements GreetingService {
    @Override
    public String sayGreetings() {
        return "Hello";
    }

@Profile("spanish")
public class SpanishServiceImpl implements GreetingService {
    @Override
    public String sayGreetings() {
        return "Hola";
    }
}

---

您使用的注释是错误的

@Profile

用于完全不同于您认为应该删除的内容

您基本上是在对spring说“请在X类中插入一个特定的问候服务”

现在spring不知道您想要哪个bean，因为您有两个不同的bean实现同一个接口。因此，我们使用

@Qualifier

注释来标记bean，并在注入期间将其作为目标

首先，您的实现应该具有

@服务

或

@组件

，以便spring在组件扫描期间找到它，并将其实例化为spring管理的bean。这与

@限定符相结合，因此我们对其进行标记，以便稍后在注入过程中选择此标记：

@Component
@Qualifier("english")
public class EnglishServiceImpl implements GreetingService {

    @Override
    public String sayGreetings() {
        return "Hello";
    }
}

在这里，我们注入问候服务，并使用限定符告诉spring我们要在可用的bean中注入哪个bean

@Service
public class EnglishLanguageService implements GreetingService {

    private GreetingService greetingService;

    public SpanishLanguageService(@Qualifier("english") GreetingService greetingService){
        this.greetingService = greetingService;
    }

    @Override
    public String sayGreetings() {
        return greetingService.sayGreetings();
    }
}

我已经完全按照你说的做了，但是现在它说它看到了4个不同的bean，而不是一个成员，你需要在你想要注入它的每个格子上使用限定符，也在你的控制器中。