java - Lambda 与 SNS -> SQS AWS

Question

我有一个 aws lambda，它将从 SNS -> SQS 触发。这意味着，我有一个 SNS，然后 SQS 是订阅者。然后我有一个由 SQS 触发的 lambda。

我已经构建了一个简单的 Lambda，如下所示

public class EnhancedCanonicalLambdaHandler implements RequestHandler<SQSEvent, String> {
    static final Logger log = LogManager.getLogger(EnhancedCanonicalLambdaHandler.class);
    static final ObjectMapper objectMapper = new ObjectMapper();

    @Override
    public String handleRequest(SQSEvent sqsEvent, Context context) {
        log.info("There are {} records to be processing ...", sqsEvent.getRecords().size());

        for(SQSEvent.SQSMessage msg : sqsEvent.getRecords()) {
// I want to map msg.getBody()
        }
    }

并且 msg.getBody 将具有如下所示的 json

{
   "Type":"Notification",
   "MessageId":"d3056919-1db0-5bcb-b5ce-3df0eb234dd9",
   "TopicArn":"arn:aws:sns:us-east-2:enhance-canonical-topic",
   "Subject":"nghia do subject",
   "Message":"{\n\"groupRuleSourceLocation\" : \"groupRuleSourceLocation\",\n\"canonicalSourceLocation\": \"canonicalSourceLocation\"\n}",
   "Timestamp":"2019-02-22T13:08:35.147Z",
   "SignatureVersion":"1",
   "SigningCertURL":"https://sns.us-east-2.amazonaws.com/.pem",
   "UnsubscribeURL":"https://sns.us-east-2.amazonaws.com/?Action=Unsubscribe&SubscriptionArn=arn:aws:sns:us-east-2:057351434671:enhance-canonical-topic:",
   "MessageAttributes":{}
}

我想看看 AWS 是否有办法将这个正文消息映射到已经定义的 Pojo？或者我们需要使用 json 或 mapper 映射到我们定义的对象？

谢谢，

Answer 1

您必须自己映射或使用映射器(如您提到的)，例如 Gson 或 Jackson

这是一个如何使用 Gson 实现此目的的示例:

Gson gson = new Gson();
String snsOrSqsMessageBody = "{\r\n   \"Type\":\"Notification\",\r\n   \"MessageId\":\"d3056919-1db0-5bcb-b5ce-3df0eb234dd9\",\r\n   \"TopicArn\":\"arn:aws:sns:us-east-2:enhance-canonical-topic\",\r\n   \"Subject\":\"nghia do subject\",\r\n   \"Message\":\"{\\n\\\"groupRuleSourceLocation\\\" : \\\"groupRuleSourceLocation\\\",\\n\\\"canonicalSourceLocation\\\": \\\"canonicalSourceLocation\\\"\\n}\",\r\n   \"Timestamp\":\"2019-02-22T13:08:35.147Z\",\r\n   \"SignatureVersion\":\"1\",\r\n   \"SigningCertURL\":\"https:\/\/sns.us-east-2.amazonaws.com\/.pem\",\r\n   \"UnsubscribeURL\":\"https:\/\/sns.us-east-2.amazonaws.com\/?Action=Unsubscribe&SubscriptionArn=arn:aws:sns:us-east-2:057351434671:enhance-canonical-topic:\",\r\n   \"MessageAttributes\":{}\r\n}";
MyCustomClass myCustomObject = gson.fromJson(snsOrSqsMessageBody, MyCustomClass.class);

出于好奇:SQS 在您的应用程序中扮演什么角色？您可以简单地将您的 Lambda 订阅到您的 SNS 主题，从而消除架构中的一层复杂性。

希望这对您有所帮助!