Spring Boot无法自动装配和运行

Question

我无法运行附加的Spring Boot采样器应用程序.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,只是向RabbitMQ Exchange发送一个消息,并绑定一个队列.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)}

Application.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);
  }
}

如果有人可以审查并提出我做错的建议,我将非常感激.

Answer 1

既然你有这样的包树:

com.company.exec
com.company.messaging

并且只使用默认值@SpringBootApplication,它只是看不到您MessageDeliveryManager及其实现.那是因为@ComponentScan(上面的元注释@SpringBootApplication)只扫描当前包及其子包.

为了使它工作,你应该添加:

@SpringBootApplication
@ComponentScan("com.company")

或者只是移动Application到根包 - com.company.