Spring 接口的引导依赖注入

Question

我有 2 个 spring 启动微服务让我们说核心和持久性。 其中持久性依赖于核心。

我在核心中定义了一个接口，其实现在持久性内部，如下所示：

核

package com.mine.service;
public interface MyDaoService {
}

持久性

package com.mine.service.impl;
@Service
public class MyDaoServiceImpl implements MyDaoService {
}

我正在尝试将 MyDaoService 注入另一个仅在核心中的服务：

核

package com.mine.service;
@Service
public class MyService {

private final MyDaoService myDaoService;

    public MyService(MyDaoService myDaoService) {
        this.myDaoService = myDaoService;
    }
}

在这样做时，我收到了这个奇怪的错误：

***************************
APPLICATION FAILED TO START
***************************

Description:

Parameter 0 of constructor in com.mine.service.MyService required a bean of type 'com.mine.service.MyDaoService' that could not be found.


Action:

Consider defining a bean of type 'com.mine.service.MyDaoService' in your configuration.

谁能解释我为什么？

注意：我已经在 springbootapplication 的组件扫描中包含了 com.mine.service 如下

package com.mine.restpi;
@SpringBootApplication
@EnableScheduling
@ComponentScan(basePackages = "com.mine")
public class MyRestApiApplication {
public static void main(String[] args) {
        SpringApplication.run(MyRestApiApplication.class, args);
    }
}

Answer 1

尝试将@Service注释添加到您的 impl 类，并将@Autowired注释添加到构造函数。

// Include the @Service annotation
@Service
public class MyServiceImpl implements MyService {

}

// Include the @Service annotation and @Autowired annotation on the constructor
@Service
public class MyDaoServiceImpl implements MyDaoService {

    private final MyService myService ;

    @Autowired
    public MyDaoServiceImpl(MyService myService){
       this.myService = myService;
    }
}

Answer 2

As stated in the error message hint: Consider defining a bean of type 'com.mine.service.MyDaoService' in your configuration to solve this problem you can define in your package com.mine a configuration class named MyConfiguration annotated with @Configuration including a名为 myDaoService 的 bean，如下所示：

@Configuration
public class MyConfiguration {
    @Bean
    public MyDaoService myDaoService() {
        return new MyDaoServiceImpl();
    }
}

Answer 3

尝试以下操作，将MyRestApiApplication class 移动到com.mine package 并删除@ComponentScan注释。

package com.mine;
@SpringBootApplication
@EnableScheduling
public class MyRestApiApplication {
public static void main(String[] args) {
        SpringApplication.run(MyRestApiApplication.class, args);
    }
}