spring-integration - Spring Integration 将有效负载转换为服务激活器中的对象

Question

我正在关注这个guide阅读 Google Pub/Sub 中某个主题的电子邮件通知。应用程序启动后，我会看到消息到达控制台，如下所示:

Message arrived! Payload: {"emailAddress":"<a href="https://stackoverflow.com/cdn-cgi/l/email-protection" class="__cf_email__" data-cfemail="0e76767676764e69636f6762206d6163" rel="noreferrer noopener nofollow">[email protected]</a>","historyId":712315}

如何将有效负载转换为对象，以便检索 emailAddress 和 HistoryId？

服务激活器如下所示:

@Bean
  @ServiceActivator(inputChannel = "pubsubInputChannel")
  public MessageHandler messageReceiver() {
    return message -> {
      LOGGER.info("Message arrived! Payload: " + message.getPayload());
      AckReplyConsumer consumer =
          (AckReplyConsumer) message.getHeaders().get(GcpPubSubHeaders.ACKNOWLEDGEMENT);
      consumer.ack();
    };
  }

我希望有效负载转换为的 POJO 对象是:

public class MessageNotification {

    private String emailAddress;

    private BigInteger historyId;

    public String getEmailAddress() {
        return emailAddress;
    }

    public BigInteger getHistoryId() {
        return historyId;
    }

    public void setHistoryId(BigInteger historyId) {
        this.historyId = historyId;
    }

    public void setEmailAddress(String emailAddress) {
        this.emailAddress = emailAddress;
    }
}

Answer 1

看起来payload是一个JSON，所以你需要去Spring Integration Reference Manual并在使用 @ServiceActivator 处理之前使用 JsonToObjectTransformer:

@Bean
@Transformer(inputChannel = "pubsubInputChannel", outputChannel = "handleChannel")
public JsonToObjectTransformer jsonToObjectTransformer() {
    return new JsonToObjectTransformer(MessageNotification.class);
}

@Bean
@ServiceActivator(inputChannel = "handleChannel")
public MessageHandler messageReceiver() {

  ...