Question

从jetS3t的示例代码示例中得到以下代码：如果我不知道要下载的文件数，该怎么办一开始？例如，在S3中具有缩略图的应用程序和客户端应用程序用户滚动缩略图列表。

将对象下载到本地文件

多线程服务提供了一种下载方法一次多个对象，但是使用这个你必须先准备一个地方放置与每个对象关联的数据。放置这些数据最明显的地方是文件，所以让我们来看一个例子将对象数据下载到文件中。要将我们的对象下载到文件中，首先必须创建一个 DownloadPackage类每个对象。这个类只是一个简单的容器将对象与a关联文件，将写入对象的数据。为每个对象创建一个DownloadPackage，以关联具有输出文件的对象。

 DownloadPackage[] downloadPackages = new DownloadPackage[5];
   downloadPackages[0] = new DownloadPackage(objects[0],
       new File(objects[0].getKey()));
   downloadPackages[1] = new DownloadPackage(objects[1],
       new File(objects[1].getKey()));
   downloadPackages[2] = new DownloadPackage(objects[2],
       new File(objects[2].getKey()));
   downloadPackages[3] = new DownloadPackage(objects[3],
       new File(objects[3].getKey()));
   downloadPackages[4] = new DownloadPackage(objects[4],
       new File(objects[4].getKey()));

   // Download the objects.
   simpleMulti.downloadObjects(bucket, downloadPackages);
   System.out.println("Downloaded objects to current working directory");

对这些案件的任何建议？提前致谢

安东尼

Answer 1

您可以列出从中下载的存储桶中的对象，并根据您定义的规则过滤键。然后你可以开始多部分下载。

从存储桶中获取密钥：



 public List getFilesList(String accessKey, String secretKey
            ,String bucketName ,String directoryPathRelativeToBucket) {
        List keys = new ArrayList();
        org.jets3t.service.model.S3Object[] objects = new org.jets3t.service.model.S3Object[]{};
        try {
            // Create a credentials object and service to access S3 account
            org.jets3t.service.security.AWSCredentials myCredentials =
                new org.jets3t.service.security.AWSCredentials(accessKey, secretKey);

        S3Service service = new RestS3Service(myCredentials);

        objects = service.listObjects(bucketName
                ,directoryPathRelativeToBucket, null);
        log.info("got bucket listing for bucket[" + bucketName + "]");
    } catch (S3ServiceException e) {
        log.error("Failed to get or object listing for bucket[" + bucketName + "] due to exception:", e);
    }

    for (org.jets3t.service.model.S3Object s3Object : objects) {
        if (s3Object.getKey().contains("$") == false) {
            keys.add(s3Object.getKey());
        }
    }
    return keys;
}

        S3Service service = new RestS3Service(myCredentials);

        objects = service.listObjects(bucketName
                ,directoryPathRelativeToBucket, null);
        log.info("got bucket listing for bucket[" + bucketName + "]");
    } catch (S3ServiceException e) {
        log.error("Failed to get or object listing for bucket[" + bucketName + "] due to exception:", e);
    }

    for (org.jets3t.service.model.S3Object s3Object : objects) {
        if (s3Object.getKey().contains("$") == false) {
            keys.add(s3Object.getKey());
        }
    }
    return keys;
}

过滤密钥后，您可以下载密钥列表的特定部分。

使用JetS3t将未知数量的文件多次上传到S3

1 个答案: