怎么让订阅关系一致

MQ 里的一个 Consumer ID 代表一个 Consumer 实例群组。对于大多数分布式应用来说，一个 Consumer ID 下通常会挂载多个 Consumer 实例。订阅关系一致指的是同一个 Consumer ID 下所有 Consumer 实例的处理逻辑必须完全一致。一旦订阅关系不一致，消息消费的逻辑就会混乱，甚至导致消息丢失。
由于 MQ 的订阅关系主要由 Topic+Tag 共同组成，因此，保持订阅关系一致意味着同一个 Consumer ID 下所有的实例需在以下两方面均保持一致：

1. 
   订阅的 Topic 必须一致；
2. 
   订阅的 Topic 中的 Tag 必须一致。

1. Properties properties = new Properties();
2. properties.put(PropertyKeyConst.ConsumerId, "CID_jodie_test_1");
3. Consumer consumer = ONSFactory.createConsumer(properties);
4. consumer.subscribe("jodie_test_A", "*", new MessageListener() {
5.     public Action consume(Message message, ConsumeContext context) {
6.         System.out.println(message.getMsgID());
7.         return Action.CommitMessage;
8.     }
9. });

1. Properties properties = new Properties();
2. properties.put(PropertyKeyConst.ConsumerId, " CID_jodie_test_1");
3. Consumer consumer = ONSFactory.createConsumer(properties);
4. consumer.subscribe("jodie_test_B ", "*", new MessageListener() {
5.     public Action consume(Message message, ConsumeContext context) {
6.         System.out.println(message.getMsgID());
7.         return Action.CommitMessage;
8.     }
9. });

1. Properties properties = new Properties();
2. properties.put(PropertyKeyConst.ConsumerId, "CID_jodie_test_2");
3. Consumer consumer = ONSFactory.createConsumer(properties);
4. consumer.subscribe("jodie_test_A", "TagA", new MessageListener() {
5.     public Action consume(Message message, ConsumeContext context) {
6.         System.out.println(message.getMsgID());
7.         return Action.CommitMessage;
8.     }
9. });

1. Properties properties = new Properties();
2. properties.put(PropertyKeyConst.ConsumerId, " CID_jodie_test_2");
3. Consumer consumer = ONSFactory.createConsumer(properties);
4. consumer.subscribe("jodie_test_A ", "*", new MessageListener() {
5.     public Action consume(Message message, ConsumeContext context) {
6.         System.out.println(message.getMsgID());
7.         return Action.CommitMessage;
8.     }
9. });

1. 同一个 Consumer ID 下订阅 Topic 个数不一致。
2. 同一个 Consumer ID 下订阅 Topic 的 Tag 不一致。

1. Properties properties = new Properties();
2. properties.put(PropertyKeyConst.ConsumerId, "CID_jodie_test_3");
3. Consumer consumer = ONSFactory.createConsumer(properties);
4. consumer.subscribe("jodie_test_A", "TagA", new MessageListener() {
5.     public Action consume(Message message, ConsumeContext context) {
6.         System.out.println(message.getMsgID());
7.         return Action.CommitMessage;
8.     }
9. });
10. consumer.subscribe("jodie_test_B", "TagB", new MessageListener() {
11.     public Action consume(Message message, ConsumeContext context) {
12.         System.out.println(message.getMsgID());
13.         return Action.CommitMessage;
14.     }
15. });

1. Properties properties = new Properties();
2. properties.put(PropertyKeyConst.ConsumerId, " CID_jodie_test_3");
3. Consumer consumer = ONSFactory.createConsumer(properties);
4. consumer.subscribe("jodie_test_A ", "TagB", new MessageListener() {
5.     public Action consume(Message message, ConsumeContext context) {
6.         System.out.println(message.getMsgID());
7.         return Action.CommitMessage;
8.     }
9. });