Amazon S3:如何获取存储桶中的文件夹列表? [英] Amazon S3: How to get a list of folders in the bucket?

问题描述

所有我发现的东西，就是这种方法获取存储桶 但是我不明白如何才能仅获得当前文件夹中的文件夹列表.我需要使用哪个前缀和定界符?可能吗?

解决方案

为示例起见，假设我在USEast1区域中有一个名为MyBucketName的存储桶，并带有以下键:

 temp/
 temp/foobar.txt
 temp/txt/
 temp/txt/test1.txt
 temp/txt/test2.txt
 temp2/

使用文件夹可能会造成混乱，因为S3本身不支持层次结构-而是，它们像其他任何S3对象一样只是键.文件夹只是S3 Web控制台中可用的抽象，它使导航存储桶变得更加容易.因此，当我们以编程方式工作时，我们希望找到与文件夹"的尺寸匹配的键(定界符"/"，大小= 0)，因为它们很可能是S3控制台向我们展示的文件夹".

两个示例的注意事项:我正在使用AWSSDK.S3版本3.1 NuGet软件包.

示例1:存储桶中的所有文件夹

此代码是从此基本示例中修改的S3文档列出了存储桶中的所有键.下面的示例将标识所有以定界符/结尾且为空的键.

IAmazonS3 client;
using (client = new AmazonS3Client(Amazon.RegionEndpoint.USEast1))
{
    // Build your request to list objects in the bucket
    ListObjectsRequest request = new ListObjectsRequest
    {
        BucketName = "MyBucketName"
    };

    do
    {
        // Build your call out to S3 and store the response
        ListObjectsResponse response = client.ListObjects(request);

        // Filter through the response to find keys that:
        // - end with the delimiter character '/' 
        // - are empty. 
        IEnumerable<S3Object> folders = response.S3Objects.Where(x =>
            x.Key.EndsWith(@"/") && x.Size == 0);

        // Do something with your output keys.  For this example, we write to the console.
        folders.ToList().ForEach(x => System.Console.WriteLine(x.Key));

        // If the response is truncated, we'll make another request 
        // and pull the next batch of keys
        if (response.IsTruncated)
        {
            request.Marker = response.NextMarker;
        }
        else
        {
            request = null;
        }
    } while (request != null);
}

预期输出到控制台:

temp/
temp/txt/
temp2/

示例2:与指定前缀匹配的文件夹

您可以通过将

应用于示例1时，我们希望获得以下输出:

temp/
temp/txt/

进一步阅读:

• S3文档-使用文件夹
• .NET SDK文档-ListObjects

All that I found, it's this method GET Bucket But I can't understand how can I get only a list of folders in the current folder. Which prefix and delimiter I need to use? Is that possible at all?

解决方案

For the sake of example, assume I have a bucket in the USEast1 region called MyBucketName, with the following keys:

 temp/
 temp/foobar.txt
 temp/txt/
 temp/txt/test1.txt
 temp/txt/test2.txt
 temp2/

Working with folders can be confusing because S3 does not natively support a hierarchy structure -- rather, these are simply keys like any other S3 object. Folders are simply an abstraction available in the S3 web console to make it easier to navigate a bucket. So when we're working programatically, we want to find keys matching the dimensions of a 'folder' (delimiter '/', size = 0) because they will likely be 'folders' as presented to us by the S3 console.

Note for both examples: I'm using the AWSSDK.S3 version 3.1 NuGet package.

Example 1: All folders in a bucket

This code is modified from this basic example in the S3 documentation to list all keys in a bucket. The example below will identify all keys that end with the delimiter character /, and are also empty.

IAmazonS3 client;
using (client = new AmazonS3Client(Amazon.RegionEndpoint.USEast1))
{
    // Build your request to list objects in the bucket
    ListObjectsRequest request = new ListObjectsRequest
    {
        BucketName = "MyBucketName"
    };

    do
    {
        // Build your call out to S3 and store the response
        ListObjectsResponse response = client.ListObjects(request);

        // Filter through the response to find keys that:
        // - end with the delimiter character '/' 
        // - are empty. 
        IEnumerable<S3Object> folders = response.S3Objects.Where(x =>
            x.Key.EndsWith(@"/") && x.Size == 0);

        // Do something with your output keys.  For this example, we write to the console.
        folders.ToList().ForEach(x => System.Console.WriteLine(x.Key));

        // If the response is truncated, we'll make another request 
        // and pull the next batch of keys
        if (response.IsTruncated)
        {
            request.Marker = response.NextMarker;
        }
        else
        {
            request = null;
        }
    } while (request != null);
}

Expected output to console:

temp/
temp/txt/
temp2/

Example 2: Folders matching a specified prefix

You could further limit this to only retrieve folders matching a specified Prefix by setting the Prefix property on ListObjectsRequest.

ListObjectsRequest request = new ListObjectsRequest
    {
        BucketName = "MyBucketName",
        Prefix = "temp/"
    };

When applied to Example 1, we would expect the following output:

temp/
temp/txt/

Further reading:

• S3 Documentation - Working With Folders
• .NET SDK Documentation - ListObjects

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