恒星支付查询

Posted 2023-02-22

【中文标题】恒星支付查询

【英文标题】：Stellar payments query

【发布时间】：2017-06-06 21:13:00

【问题描述】：

我无法在官方网站上执行示例支付查询程序。这是我的代码，与示例几乎相同。这是official website。

public class TransCheck 
  public static void main(String args[]) 
    Server server = new Server("https://horizon-testnet.stellar.org");
    KeyPair account = KeyPair.fromAccountId("GARUMRUP37CPOGQQALSXBDQQS6SUDDPKGLGFERH6PIJEHWQY5IAVZQDL");

    // Create an API call to query payments involving the account.
    // server.payments() Returns PaymentsRequestBuilder instance.
    // forAccount() Builds request to GET /accounts/account/payments - Account for which to get payments
    PaymentsRequestBuilder paymentsRequest = server.payments().forAccount(account);

    // If some payments have already been handled, start the results from the
    // last seen payment. (See below in `handlePayment` where it gets saved.)
    String lastToken = loadLastPagingToken();
    if (lastToken != null) 
      paymentsRequest.cursor(lastToken);
    

    // `stream` will send each recorded payment, one by one, then keep the
    // connection open and continue to send you new payments as they occur.

    paymentsRequest.stream(new EventListener <OperationResponse>()
      @Override
      public void onEvent(OperationResponse payment) 
        // Record the paging token so we can start from here next time.
        savePagingToken(payment.getPagingToken());

        // The payments stream includes both sent and received payments. We only
        // want to process received payments here.
        if (payment instanceof PaymentOperationResponse) 
          if (((PaymentOperationResponse) payment).getTo().equals(account)) 
            return;
          

          String amount = ((PaymentOperationResponse) payment).getAmount();

          Asset asset = ((PaymentOperationResponse) payment).getAsset();
          String assetName;
          if (asset.equals(new AssetTypeNative())) 
            assetName = "lumens";
           else 
            StringBuilder assetNameBuilder = new StringBuilder();
            assetNameBuilder.append(((AssetTypeCreditAlphaNum) asset).getCode());
            assetNameBuilder.append(":");
            assetNameBuilder.append(((AssetTypeCreditAlphaNum) asset).getIssuer().getAccountId());
            assetName = assetNameBuilder.toString();
          

          StringBuilder output = new StringBuilder();
          output.append(amount);
          output.append(" ");
          output.append(assetName);
          output.append(" from ");
          output.append(((PaymentOperationResponse) payment).getFrom().getAccountId());
          System.out.println(output.toString());
        
      
    ); 
  

我的代码中有两个错误。首先，方法：loadLastPagingToken() 未定义，我找不到该方法的详细信息。其次，当我想创建一个new EventListener <OperationResponse>() 时，IDE 告诉我

EventListener 类型不是通用的；它不能用参数进行参数化

我真的不知道为什么。请你帮助我好吗？谢谢。

【参考方案1】：

这是因为您的导入声明。

试试

导入 org.stellar.sdk.requests.EventListener;

而不是

导入 java.util.EventListener;

【参考方案2】：

对于您的第一个问题，loadLastPagingToken 的目的是获取您希望流开始的书签。由于您是第一次运行它并且没有这样的值，您应该将其设置为null。稍后，如果您正在构建重新启动流的能力，您将需要知道上次处理页面中的令牌。 loadLastPagingToken 方法在此处作为存根提供，供您在需要时实现。

CR-Soneso 已回答您的第二个问题。您导入了错误的 EventListener 类。

如果您对 Stellar 有其他疑问，您可以在 dedicated Stellar stackexchange（目前处于测试阶段）上找到更快的答案。