RabbitMQ 延迟队列实现订单支付结果异步阶梯性通知[通俗易懂]

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在第三方支付中，例如支付宝、或者微信，对于订单请求，第三方支付系统采用的是消息同步返回、异步通知+主动补偿查询的补偿机制。

由于互联网通信的不可靠性，例如双方网络、服务器、应用等因素的影响，不管是同步返回、异步通知、主动查询报文都可能出现超时无响应、报文丢失等情况，所以像支付业务，对结果的通知一般采用几种方案结合的补偿机制，不能完全依赖某一种机制。
例如一个支付结果的通知，一方面会在支付页面跳转时候返回支付结果（一般只用作前端展示使用，非最终状态），同时会采用后台异步通知机制（有前台、后台通知的，以后台异步通知结果为准），但由于前台跳转、后台结果通知都可能失效，因此还以定时补单+请求方主动查询接口作为辅助手段。
常见的补单操作，任务调度策略一般设定30秒、60秒、3分钟、6分钟、10分钟调度多次（以自己业务需要），如果调度接收到响应确认报文，补单成功，则中止对应订单的调度任务；如果超过补单上限次数，则停止补单，避免无谓的资源浪费。请求端随时可以发起请求报文查询对应订单的状态。

在日常开发中，对于网站前端来说，支付计费中心对于订单请求信息的处理也是通过消息同步返回、异步通知+主动补偿查询相结合的机制，其中对于订单的异步通知，目前的通知策略为3s、30s、60s、120s、180、300s的阶梯性通知。返回成功情况下就不继续通知了，本来打算使用将失败的消息写到数据库等待发送，然后每秒查询数据库获取消息通知前端。但觉得这样的处理方式太粗暴。存在以下缺点：

1 、每秒请求有点儿浪费资源； 2 、通知方式不稳定； 3 、无法承受大数据量等等

所以最终打算使用rabbitmq的消息延迟+死信队列来实现。消息模型如下：

producer发布消息，通过exchangeA的消息会被分发到QueueA,Consumer监听queueA，一旦有消息到来就被消费，这边的消费业务就是通知前端，如果通知失败，就创建一个延迟队列declareQueue，设置每个消息的ttl然后通过declare_exchange将消息分发到declare_queue,因为declare_queue没有consumer并且declare_queue中的消息设置了ttl，当ttl到期后，将通过DEX路由到queueA,被重新消费。

代码如下：DeclareQueue.java

1. package org.delayQueue;

2.  

3. import com.rabbitmq.client.BuiltinExchangeType;

4. import com.rabbitmq.client.Channel;

5. import com.rabbitmq.client.Connection;

6. import com.rabbitmq.client.ConnectionFactory;

7.  

8. public class DeclareQueue {


9. public static String EXCHANGE_NAME = "notifyExchange";

10.  

11. public static void init() {


12. ConnectionFactory factory = new ConnectionFactory();

13. factory.setHost("localhost");

14. factory.setPort(5672);

15.  

16. Connection connection = null;

17. try {


18. connection = factory.newConnection();

19. Channel channel = connection.createChannel();

20. channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.TOPIC);

21. String routingKey = "AliPaynotify";

22. String message = "http://localhost:8080/BossCenter/payGateway/notifyRecv.jsp?is_success=T¬ify_id=4ab9bed148d043d0bf75460706f7774a¬ify_time=2014-08-29+16%3A22%3A02¬ify_type=trade_status_sync&out_trade_no=1421712120109862&total_fee=424.42&trade_no=14217121201098611&trade_status=TRADE_SUCCESS";

23. channel.basicPublish(EXCHANGE_NAME, routingKey, null, message.getBytes());

24. System.out.println(" [x] Sent :" + message);

25. } catch (Exception e) {


26. // TODO Auto-generated catch block

27. e.printStackTrace();

28. } finally {


29. if (connection != null) {


30. try {


31. connection.close();

32. } catch (Exception ignore) {


33. }

34. }

35. }

36. }

37.  

38. public static void main(String args[]) {


39. init();

40. }

41.  

42. }

DeclareConsumer.java

1. package org.delayQueue;

2.  

3. import java.io.BufferedReader;

4. import java.io.IOException;

5. import java.io.InputStreamReader;

6. import java.util.ArrayList;

7. import java.util.HashMap;

8. import java.util.List;

9. import java.util.Map;

10. import java.util.Map.Entry;

11.  

12. import org.apache.http.HttpResponse;

13. import org.apache.http.client.ClientProtocolException;

14. import org.apache.http.client.HttpClient;

15. import org.apache.http.client.methods.HttpPost;

16. import org.apache.http.impl.client.DefaultHttpClient;

17.  

18. import com.rabbitmq.client.AMQP;

19. import com.rabbitmq.client.Channel;

20. import com.rabbitmq.client.Connection;

21. import com.rabbitmq.client.ConnectionFactory;

22. import com.rabbitmq.client.Consumer;

23. import com.rabbitmq.client.DefaultConsumer;

24. import com.rabbitmq.client.Envelope;

25.  

26. public class DeclareConsumer {


27. public static String EXCHANGE_NAME = "notifyExchange";

28. public static String QU_declare_15S = "Qu_declare_15s";

29. public static String EX_declare_15S = "EX_declare_15s";

30. public static String ROUTINGKEY = "AliPaynotify";

31. public static Connection connection = null;

32. public static Channel channel = null;

33. public static Channel DECLARE_15S_CHANNEL = null;

34. public static String declare_queue = "init";

35. public static String originalExpiration = "0";

36. public static void init() throws Exception {


37. ConnectionFactory factory = new ConnectionFactory();

38. factory.setHost("localhost");

39. factory.setPort(5672);

40. connection = factory.newConnection();

41. channel = connection.createChannel();

42. DECLARE_15S_CHANNEL = connection.createChannel();

43. }

44.  

45. public static void consume() {


46. try {


47. channel.exchangeDeclare(EXCHANGE_NAME, "topic");

48. final String queueName = channel.queueDeclare().getQueue();

49.  

50. channel.queueBind(queueName, EXCHANGE_NAME, ROUTINGKEY);

51. System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

52. final Consumer consumer = new DefaultConsumer(channel) {


53. @Override

54. public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {


55. String message = new String(body, "UTF-8");

56. Map<String, Object> headers = properties.getHeaders();

57. if (headers != null) {


58. List<Map<String, Object>> xDeath = (List<Map<String, Object>>) headers.get("x-death");

59. System.out.println("xDeath--- > " + xDeath);

60. if (xDeath != null && !xDeath.isEmpty()) {


61. Map<String, Object> entrys = xDeath.get(0);

62. // for(Entry<String, Object>

63. // entry:entrys.entrySet()){


64. // System.out.println(entry.getKey()+":"+entry.getValue());

65. // }

66. originalExpiration = entrys.get("original-expiration").toString();

67. }

68. }

69. System.out.println(" [x] Received '" + envelope.getRoutingKey() + "':'" + message + "'" + "time" + System.currentTimeMillis());

70. HttpClient httpClient = new DefaultHttpClient();

71. HttpPost post = new HttpPost(message);

72. HttpResponse response = httpClient.execute(post);

73. BufferedReader inreader = null;

74. if (response.getStatusLine().getStatusCode() == 200) {


75. inreader = new BufferedReader(new InputStreamReader(response.getEntity().getContent(), "UTF-8"));

76. StringBuffer responseBody = new StringBuffer();

77. String line = null;

78. while ((line = inreader.readLine()) != null) {


79. responseBody.append(line);

80. }

81. if (!responseBody.equals("success")) {


82. // putDeclre15s(message);

83. if (originalExpiration.equals("0")) {


84. putDeclreQueue(message, 3000, QU_declare_15S);

85. }

86. if (originalExpiration.equals("3000")) {


87. putDeclreQueue(message, 30000, QU_declare_15S);

88. }

89. if (originalExpiration.equals("30000")) {


90. putDeclreQueue(message, 60000, QU_declare_15S);

91. }

92. if (originalExpiration.equals("60000")) {


93. putDeclreQueue(message, 120000, QU_declare_15S);

94. }

95. if (originalExpiration.equals("120000")) {


96. putDeclreQueue(message, 180000, QU_declare_15S);

97. }

98. if (originalExpiration.equals("180000")) {


99. putDeclreQueue(message, 300000, QU_declare_15S);

100. }

101. if (originalExpiration.equals("300000")) {


102. // channel.basicConsume(QU_declare_300S,true, this);

103. System.out.println("finish notify");

104. }

105. }

106. } else {


107. System.out.println(response.getStatusLine().getStatusCode());

108. }

109. }

110. };

111.  

112. channel.basicConsume(queueName, true, consumer);

113. } catch (Exception e) {


114. e.printStackTrace();

115. } finally {


116. }

117. }

118.  
119.  
120.  

121. static Map<String, Object> xdeathMap = new HashMap<String, Object>();

122. static List<Map<String, Object>> xDeath = new ArrayList<Map<String, Object>>();

123. static Map<String, Object> xdeathParam = new HashMap<String, Object>();

124.  

125. public static void putDeclre15s(String message) throws IOException {


126. channel.exchangeDeclare(EX_declare_15S, "topic");

127. Map<String, Object> args = new HashMap<String, Object>();

128. args.put("x-dead-letter-exchange", EXCHANGE_NAME);// 死信exchange

129. AMQP.BasicProperties.Builder builder = new AMQP.BasicProperties.Builder();

130. builder.expiration("3000").deliveryMode(2);// 设置消息TTL

131. AMQP.BasicProperties properties = builder.build();

132. channel.queueDeclare(QU_declare_15S, false, false, false, args);

133. channel.queueBind(QU_declare_15S, EX_declare_15S, ROUTINGKEY);

134. channel.basicPublish(EX_declare_15S, ROUTINGKEY, properties, message.getBytes());

135. System.out.println("send message in QA_DEFERRED_15S" + message + "time" + System.currentTimeMillis());

136. }

137.  

138. public static void putDeclreQueue(String message, int mis, String queue) throws IOException {


139. channel.exchangeDeclare(EX_declare_15S, "topic");

140. Map<String, Object> args = new HashMap<String, Object>();

141. args.put("x-dead-letter-exchange", EXCHANGE_NAME);// 死信exchange

142. AMQP.BasicProperties.Builder builder = new AMQP.BasicProperties.Builder();

143. builder.expiration(String.valueOf(mis)).deliveryMode(2);// 设置消息TTL

144. AMQP.BasicProperties properties = builder.build();

145. channel.queueDeclare(queue, false, false, false, args);

146. channel.queueBind(queue, EX_declare_15S, ROUTINGKEY);

147. channel.basicPublish(EX_declare_15S, ROUTINGKEY, properties, message.getBytes());

148. System.out.println("send message in " + queue + message + "time============" + System.currentTimeMillis());

149. }

150.  

151. public static void main(String args[]) throws Exception {


152. init();

153. consume();

154. }

155. }

消息通过dlx转发的情况下，header头部会带有x-death的一个数组，里面包含消息的各项属性，比如说消息成为死信的原因reason，original-expiration这个字段表示消息在原来队列中的过期时间，根据这个值来确定下一次通知的延迟时间应该是多少秒。

运行结果如下：