Question

这是我的控制器代码来获取bean

@RequestMapping("/suscribetest")
    @ResponseBody
    public String subscribeTest(){
        try{
            AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MqttInboundBeans.class);
            MqttPahoMessageDrivenChannelAdapter messageChannel = context.getBean("inbound",MqttPahoMessageDrivenChannelAdapter.class);
            messageChannel.addTopic("test", 2);


        }catch(Exception ex){
            System.out.println("err "+ex.getLocalizedMessage());
        }
        return "";
    }

以下是我的bean类

@Configuration
public class MqttInboundBeans {
  @Autowired
private UserService service;


@Bean
public MessageChannel mqttInputChannel() {
    return new DirectChannel();
}

@Bean
public MessageProducer inbound() {
    MqttPahoMessageDrivenChannelAdapter adapter =
            new MqttPahoMessageDrivenChannelAdapter("tcp://localhost:1883", "testClient",
                                             "DATA/#", "LD/#");
    adapter.setCompletionTimeout(0);
    adapter.setConverter(new DefaultPahoMessageConverter());
    adapter.setQos(2);
    adapter.setOutputChannel(mqttInputChannel());
    return adapter;
}

@Bean
@ServiceActivator(inputChannel = "mqttInputChannel")
public MessageHandler handler() {
    return new MessageHandler() {

        @Override
        public void handleMessage(Message<?> message) throws MessagingException {
            System.out.println(message.getHeaders()+"  "+message.getPayload());

        }

    };
}
}

当我尝试运行应用程序时，它工作正常，我可以从messageHandler获取消息，但是当我在运行时尝试从控制器获取getBean时，我收到错误

Error creating bean with name 'mqttInboundBeans': Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.ehydromet.service.UserService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}

感谢。

Answer 1

MqttInboundBeans不生成bean UserService。 AnnotationConfigApplicationContext创建Spring Application Context接受输入作为我们使用@Configuration注释的配置类，注册Spring运行时配置类生成的所有bean。尝试自动连接应用程序上下文，然后从中获取bean。

@Autowired
private ApplicationContext context;
@RequestMapping("/suscribetest") @ResponseBody public String subscribeTest(){ 
try{ 
 MqttPahoMessageDrivenChannelAdapter messageChannel =(MqttPahoMessageDrivenChannelAdapter) context.getBean("inbound");


messageChannel.addTopic("test", 2); ....

使用context.getbeans进行依赖注入

1 个答案: