如果是高并发下，rabbitmq服务器上收到成千上万条消息，那么当打开消费端时，这些消息必定喷涌而来，导致消费端消费不过来甚至挂掉都有可能。
在非自动确认的模式下，可以采用限流模式，rabbitmq 提供了服务质量保障qos机制来控制一次消费消息数量。
下面直接上代码：
生产端：
1 package com.zxy.demo.rabbitmq;
2
3 import java.io.IOException;
4 import java.util.concurrent.TimeoutException;
5
6 import com.rabbitmq.client.AMQP;
7 import com.rabbitmq.client.Channel;
8 import com.rabbitmq.client.ConfirmListener;
9 import com.rabbitmq.client.Connection;
10 import com.rabbitmq.client.ConnectionFactory;
11 import com.rabbitmq.client.ReturnListener;
12 import com.rabbitmq.client.AMQP.BasicProperties;
13
14 public class Producter {
15
16 public static void main(String[] args) throws IOException, TimeoutException {
17 // TODO Auto-generated method stub
18 ConnectionFactory factory = new ConnectionFactory();
19 factory.setHost("192.168.10.110");
20 factory.setPort(5672);
21 factory.setUsername("guest");
22 factory.setPassword("guest");
23 factory.setVirtualHost("/");
24 Connection conn = factory.newConnection();
25 Channel channel = conn.createChannel();
26 String exchange001 = "exchange_001";
27 String queue001 = "queue_001";
28 String routingkey = "mq.topic";
29 String body = "hello rabbitmq!===============限流策略";
30 // 开启确认模式
31 channel.confirmSelect();
32 // 循环发送多条消息
33 for(int i = 0 ;i<10;i++){
34 channel.basicPublish(exchange001, routingkey, null, body.getBytes());
35 }
36
37 // 添加一个返回监听========消息返回模式重要添加
38 channel.addConfirmListener(new ConfirmListener() {
39
40 @Override
41 public void handleNack(long deliveryTag, boolean multiple) throws IOException {
42 System.out.println("===========NACK============");
43
44 }
45
46 @Override
47 public void handleAck(long deliveryTag, boolean multiple) throws IOException {
48 System.out.println("===========ACK============");
49
50 }
51 });
52 }
53
54 }
消费端：
1 package com.zxy.demo.rabbitmq;
2
3 import java.io.IOException;
4 import java.util.concurrent.TimeoutException;
5
6 import com.rabbitmq.client.Channel;
7 import com.rabbitmq.client.Connection;
8 import com.rabbitmq.client.ConnectionFactory;
9
10 public class Receiver {
11
12 public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {
13 // TODO Auto-generated method stub
14 ConnectionFactory factory = new ConnectionFactory();
15 factory.setHost("192.168.10.110");
16 factory.setPort(5672);
17 factory.setUsername("guest");
18 factory.setPassword("guest");
19 factory.setVirtualHost("/");
20 Connection conn = factory.newConnection();
21 Channel channel = conn.createChannel();
22 String exchange001 = "exchange_001";
23 String queue001 = "queue_001";
24 String routingkey = "mq.*";
25 channel.exchangeDeclare(exchange001, "topic", true, false, null);
26 channel.queueDeclare(queue001, true, false, false, null);
27 channel.queueBind(queue001, exchange001, routingkey);
28 // 设置限流策略
29 // channel.basicQos(获取消息最大数[0-无限制], 依次获取数量, 作用域[true作用于整个channel，false作用于具体消费者]);
30 channel.basicQos(0, 2, false);
31 // 自定义消费者
32 MyConsumer myConsumer = new MyConsumer(channel);
33 // 进行消费，签收模式一定要为手动签收
34 Thread.sleep(3000);
35 channel.basicConsume(queue001, false, myConsumer);
36 }
37
38 }
自定义消费者：
1 package com.zxy.demo.rabbitmq;
2
3 import java.io.IOException;
4
5 import com.rabbitmq.client.AMQP.BasicProperties;
6 import com.rabbitmq.client.Channel;
7 import com.rabbitmq.client.DefaultConsumer;
8 import com.rabbitmq.client.Envelope;
9
10 /**
11 * 可以继承，可以实现，实现的话要覆写的方法比较多，所以这里用了继承
12 *
13 */
14 public class MyConsumer extends DefaultConsumer{
15 private Channel channel;
16 public MyConsumer(Channel channel) {
17 super(channel);
18 // TODO Auto-generated constructor stub
19 this.channel=channel;
20 }
21
22 @Override
23 public void handleDelivery(String consumerTag, Envelope envelope, BasicProperties properties, byte[] body)
24 throws IOException {
25 System.out.println("消费标签："+consumerTag);
26 System.out.println("envelope.getDeliveryTag():==="+envelope.getDeliveryTag());
27 System.out.println("envelope.getExchange():==="+envelope.getExchange());
28 System.out.println("envelope.getRoutingKey():==="+envelope.getRoutingKey());
29 System.out.println("body:==="+new String(body));
30 // 手动签收，一定要有消费者签收,如果没有如下代码，则限流模式下，仅能打印出来channel.basicQos(0, 2, false);第二参数的2条信息
31 channel.basicAck(envelope.getDeliveryTag(), false);
32 }
33
34
35 }
重回队列模式，是当投递消息失败时，让该消息重新回到队列的模式，该模式需要手动签收，并需要在消费者中进行判断，调用重回队列的确认模式
代码如下
生产端：
1 package com.zxy.demo.rabbitmq;
2
3 import java.io.IOException;
4 import java.util.HashMap;
5 import java.util.Map;
6 import java.util.concurrent.TimeoutException;
7
8 import org.springframework.amqp.core.Message;
9
10 import com.rabbitmq.client.AMQP.BasicProperties;
11 import com.rabbitmq.client.Channel;
12 import com.rabbitmq.client.ConfirmListener;
13 import com.rabbitmq.client.Connection;
14 import com.rabbitmq.client.ConnectionFactory;
15 import com.rabbitmq.client.ReturnListener;
16
17 public class Producter {
18
19 public static void main(String[] args) throws IOException, TimeoutException {
20 // TODO Auto-generated method stub
21 ConnectionFactory factory = new ConnectionFactory();
22 factory.setHost("192.168.10.110");
23 factory.setPort(5672);
24 factory.setUsername("guest");
25 factory.setPassword("guest");
26 factory.setVirtualHost("/");
27 Connection conn = factory.newConnection();
28 Channel channel = conn.createChannel();
29 String exchange001 = "exchange_001";
30 String queue001 = "queue_001";
31 String routingkey = "mq.topic";
32
33 // 循环发送多条消息
34 for(int i = 0 ;i<5;i++){
35 String body = "hello rabbitmq!===============ACK&重回队列,第"+i+"条";
36 Map<String,Object> head = new HashMap<>();
37 head.put("n", i);
38 BasicProperties properties = new BasicProperties(null, "utf-8", head, 2, 1, null, null, null, null, null, null, null, null, null);
39
40 channel.basicPublish(exchange001, routingkey, properties, body.getBytes());
41 }
42
43 }
44
45 }
消费端：
1 package com.zxy.demo.rabbitmq;
2
3 import java.io.IOException;
4 import java.util.concurrent.TimeoutException;
5
6 import com.rabbitmq.client.Channel;
7 import com.rabbitmq.client.Connection;
8 import com.rabbitmq.client.ConnectionFactory;
9
10 public class Receiver {
11
12 public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {
13 // TODO Auto-generated method stub
14 ConnectionFactory factory = new ConnectionFactory();
15 factory.setHost("192.168.10.110");
16 factory.setPort(5672);
17 factory.setUsername("guest");
18 factory.setPassword("guest");
19 factory.setVirtualHost("/");
20 Connection conn = factory.newConnection();
21 Channel channel = conn.createChannel();
22 String exchange001 = "exchange_001";
23 String queue001 = "queue_001";
24 String routingkey = "mq.*";
25 channel.exchangeDeclare(exchange001, "topic", true, false, null);
26 channel.queueDeclare(queue001, true, false, false, null);
27 channel.queueBind(queue001, exchange001, routingkey);
28 // 自定义消费者
29 MyConsumer myConsumer = new MyConsumer(channel);
30 // 进行消费，签收模式一定要为手动签收
31 channel.basicConsume(queue001, false, myConsumer);
32 }
33
34 }
自定义消费者：
1 package com.zxy.demo.rabbitmq;
2
3 import java.io.IOException;
4
5 import com.rabbitmq.client.AMQP.BasicProperties;
6 import com.rabbitmq.client.Channel;
7 import com.rabbitmq.client.DefaultConsumer;
8 import com.rabbitmq.client.Envelope;
9
10 /**
11 * 可以继承，可以实现，实现的话要覆写的方法比较多，所以这里用了继承
12 *
13 */
14 public class MyConsumer extends DefaultConsumer{
15 private Channel channel;
16 public MyConsumer(Channel channel) {
17 super(channel);
18 // TODO Auto-generated constructor stub
19 this.channel=channel;
20 }
21
22 @Override
23 public void handleDelivery(String consumerTag, Envelope envelope, BasicProperties properties, byte[] body)
24 throws IOException {
25 System.out.println("消费标签："+consumerTag);
26 System.out.println("envelope.getDeliveryTag():==="+envelope.getDeliveryTag());
27 System.out.println("envelope.getExchange():==="+envelope.getExchange());
28 System.out.println("envelope.getRoutingKey():==="+envelope.getRoutingKey());
29 System.out.println("body:==="+new String(body));
30 System.out.println("===================休眠以便查看===============");
31 try {
32 Thread.sleep(2000);
33 } catch (InterruptedException e) {
34 // TODO Auto-generated catch block
35 e.printStackTrace();
36 }
37 // 手动签收
38 Integer i = (Integer) properties.getHeaders().get("n");
39 System.out.println("iiiiiiiiiiiiiiiii======================================================"+i);
40 if(i==1) {
41 channel.basicNack(envelope.getDeliveryTag(),false, true);//第三个参数为是否重返队列
42 }else {
43 channel.basicAck(envelope.getDeliveryTag(), false);
44 }
45 }
46
47
48 }
下面是重回队列执行结果，可以看到当消费完后第一条不断的被扔回队列然后消费再扔回。
1 消费标签：amq.ctag-eeeaa9jgrJ3tDhtQR2XReg 2 envelope.getDeliveryTag():===1 3 envelope.getExchange():===exchange_001 4 envelope.getRoutingKey():===mq.topic 5 body:===hello rabbitmq!===============ACK&重回队列,第0条 6 ===================休眠以便查看=============== 7 iiiiiiiiiiiiiiiii======================================================0 8 消费标签：amq.ctag-eeeaa9jgrJ3tDhtQR2XReg 9 envelope.getDeliveryTag():===2 10 envelope.getExchange():===exchange_001 11 envelope.getRoutingKey():===mq.topic 12 body:===hello rabbitmq!===============ACK&重回队列,第1条 13 ===================休眠以便查看=============== 14 iiiiiiiiiiiiiiiii======================================================1 15 消费标签：amq.ctag-eeeaa9jgrJ3tDhtQR2XReg 16 envelope.getDeliveryTag():===3 17 envelope.getExchange():===exchange_001 18 envelope.getRoutingKey():===mq.topic 19 body:===hello rabbitmq!===============ACK&重回队列,第2条 20 ===================休眠以便查看=============== 21 iiiiiiiiiiiiiiiii======================================================2 22 消费标签：amq.ctag-eeeaa9jgrJ3tDhtQR2XReg 23 envelope.getDeliveryTag():===4 24 envelope.getExchange():===exchange_001 25 envelope.getRoutingKey():===mq.topic 26 body:===hello rabbitmq!===============ACK&重回队列,第3条 27 ===================休眠以便查看=============== 28 iiiiiiiiiiiiiiiii======================================================3 29 消费标签：amq.ctag-eeeaa9jgrJ3tDhtQR2XReg 30 envelope.getDeliveryTag():===5 31 envelope.getExchange():===exchange_001 32 envelope.getRoutingKey():===mq.topic 33 body:===hello rabbitmq!===============ACK&重回队列,第4条 34 ===================休眠以便查看=============== 35 iiiiiiiiiiiiiiiii======================================================4 36 消费标签：amq.ctag-eeeaa9jgrJ3tDhtQR2XReg 37 envelope.getDeliveryTag():===6 38 envelope.getExchange():===exchange_001 39 envelope.getRoutingKey():===mq.topic 40 body:===hello rabbitmq!===============ACK&重回队列,第1条 41 ===================休眠以便查看=============== 42 iiiiiiiiiiiiiiiii======================================================1 43 消费标签：amq.ctag-eeeaa9jgrJ3tDhtQR2XReg 44 envelope.getDeliveryTag():===7 45 envelope.getExchange():===exchange_001 46 envelope.getRoutingKey():===mq.topic 47 body:===hello rabbitmq!===============ACK&重回队列,第1条 48 ===================休眠以便查看=============== 49 iiiiiiiiiiiiiiiii======================================================1 50 消费标签：amq.ctag-eeeaa9jgrJ3tDhtQR2XReg 51 envelope.getDeliveryTag():===8 52 envelope.getExchange():===exchange_001 53 envelope.getRoutingKey():===mq.topic 54 body:===hello rabbitmq!===============ACK&重回队列,第1条 55 ===================休眠以便查看=============== 56 iiiiiiiiiiiiiiiii======================================================1 57 消费标签：amq.ctag-eeeaa9jgrJ3tDhtQR2XReg 58 envelope.getDeliveryTag():===9 59 envelope.getExchange():===exchange_001 60 envelope.getRoutingKey():===mq.topic 61 body:===hello rabbitmq!===============ACK&重回队列,第1条 62 ===================休眠以便查看===============