我有两个SpringBoot应用程序，我在其中使用RabbitMQ在整个队列中传递消息。构建了一个应用程序来发送消息，而另一个则侦听已发送的消息。每个应用程序都包含一个@SpringBootApplication文件，该文件在属性级别具有一个@Autowired依赖项（一个应用程序具有发送者，另一个具有侦听器），每个应用程序都有一个单独的Spring
@Configuration文件，该文件分别声明一个bean（一个具有发送者）还有一个接收器）。

由于某种原因，Sender应用程序的注入没有问题，但是，即使bean在我的应用程序上下文中，Receiver应用程序也没有在@Autowire进行注入。我正在使用示例应用程序作为向我们公司展示带有SpringBoot和微服务的RabbitMQ
/
SpringAMQP的一种方式。以下是发送方应用程序的代码，其后是接收方应用程序的代码。如果我将Receiver应用程序更改为使用Setter注入，则可以正常工作，我很好奇为什么其中一个有效而另一个无效。Receiver应用程序在其main方法中会在receive.receive（）调用上爆炸，如下所示：

com.bettercloud.SpringAmqpApplication.main（SpringAmqpApplication.java:17）中的线程“主”中的异常java.lang.NullPointerException

接收器应用程序：

@SpringBootApplication
public class SpringAmqpApplication {

@Autowired
static Recv receiver;
public static void main(String[] args) throws IOException,InterruptedException {
    SpringApplication.run(SpringAmqpApplication.class, args);
    receiver.receive();
  }
 }

@Configuration
public class Config {

@Bean
public Recv recv(){
    return new Recv();
 }
 }


 public class Recv {

 private final static String QUEUE_NAME = "task_queue";
 public void receive()
        throws java.io.IOException,
        InterruptedException {

    ConnectionFactory factory = new ConnectionFactory();
    factory.setHost("localhost");
    Connection connection = factory.newConnection();
    Channel channel = connection.createChannel();

    channel.queueDeclare(QUEUE_NAME, true, false, false, null);
    System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

    channel.basicQos(1);

    QueueingConsumer consumer = new QueueingConsumer(channel);
    channel.basicConsume(QUEUE_NAME, false, consumer);

    while (true) {
        QueueingConsumer.Delivery delivery = consumer.nextDelivery();
        String message = new String(delivery.getBody());

        System.out.println(" [x] Received '" + message + "'");
        doWork(message);
        System.out.println(" [x] Done");
        channel.basicAck(delivery.getEnvelope().getDeliveryTag(), false);
    }
  }

private static void doWork(String task) throws InterruptedException {
    for (char ch: task.toCharArray()) {
        if (ch == '.') Thread.sleep(1000);
    }
  }
}

发件人申请：

@SpringBootApplication
public class SpringAmqpProducerApplication {

@Autowired
static Send sender;

public static void main(String[] args) throws IOException {
    SpringApplication.run(SpringAmqpProducerApplication.class, args);
    sender.send(null);
   }
 }


@Configuration
public class Config {

@Bean
public Send send(){
    return new Send();
    }
 }

public class Send {

private final static String QUEUE_NAME = "task_queue";

public static void send(String[] argv)
        throws java.io.IOException {
    Connection connection = null;
    Channel channel = null;
    try {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("localhost");
        connection = factory.newConnection();
        channel = connection.createChannel();

        channel.queueDeclare(QUEUE_NAME, true, false, false, null);
        String message = getMessage(argv);
        channel.basicPublish("", QUEUE_NAME, MessageProperties.PERSISTENT_TEXT_PLAIN, message.getBytes());
        System.out.println(" [x] Sent '" + message + "'");
    } finally {
        channel.close();
        connection.close();
     }
  }

private static String getMessage(String[] strings){
    if (strings == null || strings.length < 1)
        return "Hello World!";
    return joinStrings(strings, " ");
}

private static String joinStrings(String[] strings, String delimiter) {
    int length = strings.length;
    if (length == 0) return "";
    StringBuilder words = new StringBuilder(strings[0]);
    for (int i = 1; i < length; i++) {
        words.append(delimiter).append(strings[i]);
    }
    return words.toString();
 }
}