将消息存储到变量 RabbitMQ Java答案

【问题标题】：Store messages to variable RabbitMQ Java将消息存储到变量 RabbitMQ Java
【发布时间】：2018-09-01 16:47:14
【问题描述】：

这是我在 rmq 中接收消息的接收函数。这里有更多解释：https://www.rabbitmq.com/tutorials/tutorial-one-java.html

此代码显示我的消息，但我想将它们存储在变量中。

问题是handleDelivery 无效。当我将 void 更改为 String 我得到：

“返回类型与DefaultConsumer.handleDelivery(String, Envelope, AMQP.BasicProperties, byte[])不兼容”

关于如何将消息存储在变量中的任何想法？

        public String recv() throws Exception
        {
            System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
            Consumer consumer = new DefaultConsumer(channelRecv) 
              {
                 @Override
                 public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) 
                 throws IOException 
              {
                String message = new String(body, "UTF-8");  
                System.out.println(" [x] Received '" + message + "'");
                return message;
              }      

            };
            channelRecv.basicConsume(queRecv, true, consumer);

        }

编辑：这是我运行主程序时遇到的错误

The error is: Exception in thread "main" java.io.IOException
at com.rabbitmq.client.impl.AMQChannel.wrap(AMQChannel.java:105)
at com.rabbitmq.client.impl.AMQChannel.wrap(AMQChannel.java:101)
at com.rabbitmq.client.impl.ChannelN.basicConsume(ChannelN.java:1255)
at com.rabbitmq.client.impl.recovery.AutorecoveringChannel.basicConsume(AutorecoveringChannel.java:471)
at com.rabbitmq.client.impl.recovery.AutorecoveringChannel.basicConsume(AutorecoveringChannel.java:461)
at com.rabbitmq.client.impl.recovery.AutorecoveringChannel.basicConsume(AutorecoveringChannel.java:456)
at Recv.recv(Recv.java:44)
at mainLaptop.main(mainLaptop.java:11)
Caused by: com.rabbitmq.client.ShutdownSignalException: channel error; protocol method: #method<channel.close>(reply-code=404, reply-text=NOT_FOUND - no queue 'Leonardo' in vhost '/', class-id=60, method-id=20)
at com.rabbitmq.utility.ValueOrException.getValue(ValueOrException.java:66)
at com.rabbitmq.utility.BlockingValueOrException.uninterruptibleGetValue(BlockingValueOrException.java:32)
at com.rabbitmq.client.impl.AMQChannel$BlockingRpcContinuation.getReply(AMQChannel.java:366)
at com.rabbitmq.client.impl.ChannelN.basicConsume(ChannelN.java:1253)
... 5 more

这是我的代码

    public class Recv 
    {

public static String recv(String ip, String Q) throws Exception 
{

    ConnectionFactory factory = new ConnectionFactory();
    factory.setHost(ip);
    factory.setUsername("test");
    factory.setPassword("test");
    Connection connection = factory.newConnection();
    Channel channel = connection.createChannel();

    System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
    MyConsumer consumer=new MyConsumer(channel);
    channel.basicConsume(Q,true,consumer);

    return consumer.getStoredMessage();
}

public static class MyConsumer extends DefaultConsumer 
{
    private String storedMessage;

    public MyConsumer(Channel channel) 
    {
        super(channel);
    }

    public String getStoredMessage() 
    {
        return storedMessage;
    }

    @Override
    public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body)
        throws IOException 
    {
        String message = new String(body, "UTF-8");
        System.out.println(" [x] Received '" + message + "'");
        storedMessage = message; // store message here
    }
}
}

【问题讨论】：

标签： java windows rabbitmq queue message-queue

【解决方案1】：

您可以创建 DefaultConsumer 类的自定义扩展，它可以设置/获取结果

public String recv() throws Exception {
    System.out.println(" [*] Waiting for messages. To exit press CTRL+C");
    MyConsumer consumer=new MyConsumer(channelRecv);
    channelRecv.basicConsume(queRecv,true,consumer);

    consumer.getStoredMessage(); // use stored value here
}

public class MyConsumer extends DefaultConsumer {
    private String storedMessage;

    public MyConsumer(Object channelRecv) {
        super(channelRecv);
    }

    public String getStoredMessage() {
        return storedMessage;
    }

    @Override
    public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body)
            throws IOException {
        String message = new String(body, "UTF-8");
        System.out.println(" [x] Received '" + message + "'");
        storedMessage = message; // store message here
    }
}

【讨论】：