Question

我正在尝试在Spring Boot应用程序中为Service类使用@Autowired注释，但它不断抛出No qualifying bean of type异常。但是，如果我将服务类更改为bean，那么它可以正常工作。这是我的代码：

package com.mypkg.domain;
@Service
public class GlobalPropertiesLoader {

    @Autowired
    private SampleService sampleService;        
}

package com.mypkg.service;
@Service
public class SampleService{

}

这是我的SpringBoot类：

package com.mypkg;

import java.util.Set;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.data.rest.webmvc.config.RepositoryRestMvcConfiguration;
import org.springframework.transaction.annotation.EnableTransactionManagement;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Import;

@SpringBootApplication
@EnableJpaRepositories
@Import(RepositoryRestMvcConfiguration.class)
@EnableTransactionManagement
public class TrackingService {
    private static final Logger LOGGER = LoggerFactory.getLogger(TrackingService.class);

    static AnnotationConfigApplicationContext context;

    public static void main(String[] args) throws Exception {
        SpringApplication.run(TrackingService.class, args);
        context = new AnnotationConfigApplicationContext();
        context.refresh();
        context.close();

    }

}

当我尝试运行它时，我得到以下异常：

Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.mypkg.service.SampleService] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

但是当我从SampleService类中删除@Service注释，并将其作为bean添加到我的AppConfig类中时，如下所示，它可以正常工作：

@Configuration
public class AppServiceConfig {

    public AppServiceConfig() {
    }

    @Bean(name="sampleService")
    public SampleService sampleService(){
        return new SampleService();
    }

}

这些类位于不同的包中。我没有使用@ComponentScan。相反，我正在使用@SpringBootApplication自动执行此操作。但是，我尝试使用ComponentScan，但这没有帮助。

我在这里做错了什么？

Answer 1

您正在使用两种方法来构建Spring的bean。你只需要使用其中一个。

通过POJO的@Service
```
@Service
public class SampleService
```

配置类中的@Bean必须使用@Configuration

进行注释

@Bean
public SampleService sampleService(){
    return new SampleService();
}

@Autowired由类类型解析，然后不需要@Bean(name="sampleService")你是否只有一个具有该类类型的bean。

编辑01

package com.example

@SpringBootApplication
public class Application implements CommandLineRunner {

public static void main(String... args) {
    SpringApplication.run(Application.class);
}

@Autowired
private UserRepository userRepository;

@Autowired
private UserService userService;

@Override
public void run(String... strings) throws Exception {
    System.out.println("repo " + userRepository);
    System.out.println("serv " + userService);
}
}

package com.example.config

@Configuration
public class AppConfig {

@Bean
public UserRepository userRepository() {
    System.out.println("repo from bean");
    return new UserRepository();
}

@Bean
public UserService userService() {
    System.out.println("ser from bean");
    return new UserService();
}
}

package com.example.repository

@Service
public class UserRepository {

@PostConstruct
public void init() {
    System.out.println("repo from @service");
}
}

package com.example.service

@Service
public class UserService {

@PostConstruct
public void init() {
    System.out.println("service from @service");
}

}

使用此代码，您可以注释AppConfig类，然后您将了解UserRepository和UserService如何自动装配。在每个类中注释@Service并取消注释AppConfig和类也将自动装配。

Spring引号注释@Autowired of Service失败

1 个答案: