RocketMQ-消息消费模式

集群模式

在消费模式为集群的情况下,如果机器是集群的,消息只会给集群中的其中一台机器消费到

集群模式的演示(本身就默认)

假设我们生产者生产了十条信息 ，当我们集群了两台消费者服务器的时候，就会每个服务器执行五条

Rocketmq存储队列

在消息中间件每个topic是有4个写和读队列,主要是解决并发性能的问题的
如果只有一个队列，保证线程安全，必须得给队列进行写操作的时候上锁。
多几个队列，降低并发度，等待时间就短一些。

为什么是四个队列?

因为大多数服务器只有四核，意味着同时最多只能有CPU同时工作

广播模式

在消费模式为集群的情况下，如果机器是集群的，消费是会给集群中的所有机器所消费到

public class Consumer {    public static void main(String[] args) throws Exception {        //定义消息消费者(在同一个JVM中,消费者的组名不能重复)        DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("helloConsumerGroup");        //设置nameServer地址        consumer.setNamesrvAddr("43.143.161.59:9876");        //设置订阅的主题        consumer.subscribe("helloTopic","*");        //设置消费模式        consumer.setMessageModel(MessageModel.BROADCASTING);        //设置消息的监听器        consumer.setMessageListener(new MessageListenerConcurrently() {            @Override            public ConsumeConcurrentlyStatus consumeMessage(List list, ConsumeConcurrentlyContext consumeConcurrentlyContext) {                for(MessageExt msg:list){                    String s = new String(msg.getBody(), Charset.defaultCharset());                    System.out.println("线程:"+Thread.currentThread()+",消息的内容:"+s);                }                return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;            }        });        //启动消费者        consumer.start();    }}

运行结果：

生产者发送了十条消息之后，消费者集群的每个服务器均收到十条数据

顺序消费

实现生产顺序:12345消费顺序12345
哪些消息要实现顺序消费,就要让那些消息进入到同一个队列当中,对于消费者来说,一个队列对于一个线程

假设我们没有实现顺序消费的时候

创建生产者

创建实体类

@Setter@Getterpublic class OrderStep {    private long orderId;    private String desc;    @Override    public String toString() {        return "OrderStep{" +                "orderId=" + orderId +                ", desc='" + desc + '\'' +                '}';    }}

创建测试类

public class OrderUtil {    public static List buildOrders(){        List orderList = new ArrayList();        OrderStep orderDemo = new OrderStep();        orderDemo.setOrderId(15103111039L);        orderDemo.setDesc("创建");        orderList.add(orderDemo);        orderDemo = new OrderStep();        orderDemo.setOrderId(15103111065L);        orderDemo.setDesc("创建");        orderList.add(orderDemo);        orderDemo = new OrderStep();        orderDemo.setOrderId(15103111039L);        orderDemo.setDesc("付款");        orderList.add(orderDemo);        orderDemo = new OrderStep();        orderDemo.setOrderId(15103117235L);        orderDemo.setDesc("创建");        orderList.add(orderDemo);        orderDemo = new OrderStep();        orderDemo.setOrderId(15103111065L);        orderDemo.setDesc("付款");        orderList.add(orderDemo);        orderDemo = new OrderStep();        orderDemo.setOrderId(15103117235L);        orderDemo.setDesc("付款");        orderList.add(orderDemo);        orderDemo = new OrderStep();        orderDemo.setOrderId(15103111065L);        orderDemo.setDesc("完成");        orderList.add(orderDemo);        orderDemo = new OrderStep();        orderDemo.setOrderId(15103111039L);        orderDemo.setDesc("推送");        orderList.add(orderDemo);        orderDemo = new OrderStep();        orderDemo.setOrderId(15103117235L);        orderDemo.setDesc("完成");        orderList.add(orderDemo);        orderDemo = new OrderStep();        orderDemo.setOrderId(15103111039L);        orderDemo.setDesc("完成");        orderList.add(orderDemo);        return orderList;    }}

创建生产者类

public class Producer {        public static void main(String[] args) throws Exception {            DefaultMQProducer producer = new DefaultMQProducer("orderlyProducerGroup");            producer.setNamesrvAddr("43.143.161.59:9876");            producer.start();            String topic = "orderTopic";            List orderSteps = OrderUtil.buildOrders();            for(OrderStep step:orderSteps){                Message msg = new Message(topic,step.toString().getBytes(Charset.defaultCharset()));                producer.sendOneway(msg);            }            producer.shutdown();        }}

创建消费者类

public class Consumer {    public static void main(String[] args) throws Exception {        DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("orderlyConsumerGroup");        consumer.setNamesrvAddr("43.143.161.59:9876");        consumer.subscribe("orderTopic","*");        consumer.setMessageModel(MessageModel.BROADCASTING);        consumer.setMessageListener(new MessageListenerConcurrently() {            @Override            public ConsumeConcurrentlyStatus consumeMessage(List list, ConsumeConcurrentlyContext consumeConcurrentlyContext) {                for(MessageExt msg:list){                    String s = new String(msg.getBody(), Charset.defaultCharset());                    System.out.println("线程:"+Thread.currentThread()+",消息的内容:"+s);                }                return ConsumeConcurrentlyStatus.CONSUME_SUCCESS;            }        });        //启动消费者        consumer.start();    }}

运行结果：

可以看出和我们生产数据的顺序完全不同，整个订单的顺序都反了

如何改实现顺序消费

生产者类

public class Producer {    public static void main(String[] args) throws Exception {        DefaultMQProducer producer = new DefaultMQProducer("orderlyProducerGroup");        producer.setNamesrvAddr("43.143.161.59:9876");        producer.start();        String topic = "orderTopic";        List orderSteps = OrderUtil.buildOrders();        //设置队列选择器        MessageQueueSelector selector = new MessageQueueSelector() {            @Override            public MessageQueue select(List list, Message message, Object o) {                System.out.println("队列个数"+list.size());                Long orderId = (Long) o;                int index = (int)(orderId % list.size());                return list.get(index);            }        };        for(OrderStep step:orderSteps){            Message msg = new Message(topic,step.toString().getBytes(Charset.defaultCharset()));            //指定消息选择器,换入的参数            producer.send(msg,selector,step.getOrderId());        }        producer.shutdown();    }}

消费者类

public class Consumer {    public static void main(String[] args) throws Exception {        DefaultMQPushConsumer consumer = new DefaultMQPushConsumer("orderlyConsumerGroup");        consumer.setNamesrvAddr("43.143.161.59:9876");        consumer.subscribe("orderTopic","*");        //从什么地方开始消费        consumer.setConsumeFromWhere(ConsumeFromWhere.CONSUME_FROM_FIRST_OFFSET);        //一个队列对应一个线程        consumer.setMessageListener(new MessageListenerOrderly() {            @Override            public ConsumeOrderlyStatus consumeMessage(List list, ConsumeOrderlyContext consumeOrderlyContext) {                for(MessageExt msg:list){                    System.out.println("当前线程："+Thread.currentThread()+":,队列ID"+msg.getQueueId()+",消息内容："+new String(msg.getBody(),Charset.defaultCharset()));                }                return ConsumeOrderlyStatus.SUCCESS;            }        });        //启动消费者        consumer.start();    }}

来源地址：https://blog.csdn.net/m0_62434717/article/details/128988855