Spring Boot 无法 Autowiring 和运行

Question

我无法运行 attached Spring Boot sampler application .它有一个 AMQP 启动器，需要 RabbitMQ。从根本上说，它是一个简单的应用程序，它只是将一条消息发送到绑定(bind)了一个队列的 RabbitMQ Exchange。我收到以下错误:

Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: com.company.messaging.MessageDeliveryManager com.company.exec.Application.messageDeliveryManager; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.company.messaging.MessageDeliveryManager] 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)}

应用程序.java

package com.company.exec;

@SpringBootApplication
public class Application implements CommandLineRunner {

  @Autowired
  MessageDeliveryManager messageDeliveryManager;

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

  public void run(String... args) throws Exception {
    messageDeliveryManager.sendMessage(String message);
  }
}

MessageDeliveryManager.java

package com.company.messaging;

public interface MessageDeliveryManager {
  void sendMessage(String message);
}

MessageDeliveryImpl.java

package com.company.messaging;

public class MessageDeliveryManagerImpl implements MessageDeliveryManager {

  @Value("${app.exchangeName}")
  String exchangeName;

  @Value("${app.queueName}")
  String queueName;

  @Autowired
  RabbitTemplate rabbitTemplate;

  @Bean
  Queue queue() {
    return new Queue(queueName, false);
  }

  @Bean
  DirectExchange exchange() {
    return new DirectExchange(exchangeName);
  }

  @Bean
  Binding binding(Queue queue, DirectExchange exchange) {
    return BindingBuilder.bind(queue).to(exchange).with(queueName);
  }

  public void sendMessage(String message) {
    rabbitTemplate.send(queueName, message);
  }
}

如果有人可以审查我做错的地方并提出建议，我将不胜感激。

Answer 1

因为你有这样一个包树:

com.company.exec
com.company.messaging

并且只使用默认的 @SpringBootApplication，它只是看不到您的 MessageDeliveryManager 及其实现。这是因为 @ComponentScan(@SpringBootApplication 上的元注释)只扫描当前包及其子包。

要使其正常工作，您应该添加以下内容:

@SpringBootApplication
@ComponentScan("com.company")

或者只是将您的 Application 移动到根包 - com.company。