本文介绍如何列举文件。

列举文件的完整代码请参见GitHub。

OSS文件按照字母顺序排列。您可以通过ListObjects列出存储空间下的文件。主要的参数如下：

参数 说明
Delimiter 对文件名称进行分组的一个字符。CommonPrefixes是以delimiter结尾，并有共同前缀的文件集合。
Marker 标明本次列举文件的起点。
MaxKeys 列举文件的最大个数。默认为100，最大值为1000。
Prefix 本次查询结果的前缀。

简单列举文件

简单列举文件的完整代码请参见GitHub。

以下代码用于列举指定存储空间下的文件：

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using Aliyun.OSS;
var endpoint = "<yourEndpoint>";
var accessKeyId = "<yourAccessKeyId>";
var accessKeySecret = "<yourAccessKeySecret>";
var bucketName = "<yourBucketName>";
// 创建OssClient实例。
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{
    var listObjectsRequest = new ListObjectsRequest(bucketName);
    // 简单列举存储空间下的文件，默认返回100条记录。
    var result = client.ListObjects(listObjectsRequest);
    Console.WriteLine("List objects succeeded");
    foreach (var summary in result.ObjectSummaries)
    {
        Console.WriteLine("File name:{0}", summary.Key);
    }
}
catch (Exception ex)
{
    Console.WriteLine("List objects failed. {0}", ex.Message);
}

列举指定个数的文件

以下代码用于列举指定个数的文件：

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using Aliyun.OSS;
var endpoint = "<yourEndpoint>";
var accessKeyId = "<yourAccessKeyId>";
var accessKeySecret = "<yourAccessKeySecret>";
var bucketName = "<yourBucketName>";
// 创建OssClient实例。
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{
    var listObjectsRequest = new ListObjectsRequest(bucketName)
    {
        // 最大返回200条记录。
        MaxKeys = 200,
    };
    var result = client.ListObjects(listObjectsRequest);
    Console.WriteLine("List objects succeeded");
    foreach (var summary in result.ObjectSummaries)
    {
        Console.WriteLine(summary.Key);
    }
}
catch (Exception ex)
{
    Console.WriteLine("List objects failed, {0}", ex.Message);
}

列举指定前缀的文件

以下代码用于列举包含指定前缀（prefix）的文件：

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using Aliyun.OSS;
using Aliyun.OSS.Common;
var endpoint = "<yourEndpoint>";
var accessKeyId = "<yourAccessKeyId>";
var accessKeySecret = "<yourAccessKeySecret>";
var bucketName = "<yourBucketName>";
var prefix = "<yourObjectPrefix>";
// 创建OssClient实例。
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{
    var keys = new List<string>();
    ObjectListing result = null;
    string nextMarker = string.Empty;
    do
    {
        var listObjectsRequest = new ListObjectsRequest(bucketName)
        {
            Marker = nextMarker,
            MaxKeys = 100,
            Prefix = prefix,
        };
        result = client.ListObjects(listObjectsRequest);
        foreach (var summary in result.ObjectSummaries)
        {
            Console.WriteLine(summary.Key);
            keys.Add(summary.Key);
        }
        nextMarker = result.NextMarker;
    } while (result.IsTruncated);
    Console.WriteLine("List objects of bucket:{0} succeeded ", bucketName);
}
catch (OssException ex)
{
    Console.WriteLine("Failed with error code: {0}; Error info: {1}. \nRequestID:{2}\tHostID:{3}",
        ex.ErrorCode, ex.Message, ex.RequestId, ex.HostId);
}
catch (Exception ex)
{
    Console.WriteLine("Failed with error info: {0}", ex.Message);
}

列举指定marker之后的文件

参数marker代表文件名称。以下代码用于列举指定marker之后的文件：

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using Aliyun.OSS;
using Aliyun.OSS.Common;
var endpoint = "<yourEndpoint>";
var accessKeyId = "<yourAccessKeyId>";
var accessKeySecret = "<yourAccessKeySecret>";
var bucketName = "<yourBucketName>";
var marker = "<yourObjectMarker>";
// 创建OssClient实例。
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{
    var keys = new List<string>();
    ObjectListing result = null;
    string nextMarker = marker;
    do
    {
        var listObjectsRequest = new ListObjectsRequest(bucketName)
        // 若想增大返回文件数目，可以修改MaxKeys参数，或者使用Marker参数分次读取。
        {
            Marker = nextMarker,
            MaxKeys = 100,
        };
        result = client.ListObjects(listObjectsRequest);
        foreach (var summary in result.ObjectSummaries)
        {
            Console.WriteLine(summary.Key);
            keys.Add(summary.Key);
        }
        nextMarker = result.NextMarker;
    // 如果IsTruncated为 true， NextMarker将作为下次读取的起点。
    } while (result.IsTruncated);
    Console.WriteLine("List objects of bucket:{0} succeeded ", bucketName);
}
catch (OssException ex)
{
    Console.WriteLine("Failed with error code: {0}; Error info: {1}. \nRequestID:{2}\tHostID:{3}",
        ex.ErrorCode, ex.Message, ex.RequestId, ex.HostId);
}
catch (Exception ex)
{
    Console.WriteLine("Failed with error info: {0}", ex.Message);
}

通过异步方式列举文件

通过异步方式列举文件完整代码请参见GitHub。

以下代码用于异步方式列举文件：

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using System;
using System.IO;
using System.Threading;
using Aliyun.OSS;
namespace AsyncListObjects
{
    class Program
    {
        static string endpoint = "<yourEndpoint>";
        static string accessKeyId = "<yourAccessKeyId>";
        static string accessKeySecret = "<yourAccessKeySecret>";
        static string bucketName = "<yourBucketName>";
        static AutoResetEvent _event = new AutoResetEvent(false);
        // 创建OssClient实例。
        static OssClient client = new OssClient(endpoint, accessKeyId, accessKeySecret);
        static void Main(string[] args)
        {
            Program.AsyncListObjects();
            Console.ReadKey();
        }
        public static void AsyncListObjects()
        {
            try
            {
                var listObjectsRequest = new ListObjectsRequest(bucketName);
                client.BeginListObjects(listObjectsRequest, ListObjectCallback, null);
                _event.WaitOne();
            }
            catch (Exception ex)
            {
                Console.WriteLine("Async list objects failed. {0}", ex.Message);
            }
        }
        // 通过ListObjectCallback方法异步调用结束后执行回调，如果使用异步类型的接口，都需要实现类似接口。
        private static void ListObjectCallback(IAsyncResult ar)
        {
            try
            {
                var result = client.EndListObjects(ar);
                foreach (var summary in result.ObjectSummaries)
                {
                    Console.WriteLine("文件名称: {0}", summary.Key);
                }
                _event.Set();
                Console.WriteLine("Async list objects succeeded");
            }
            catch (Exception ex)
            {
                Console.WriteLine("Async list objects failed. {0}", ex.Message);
            }
        }
    }
}

列举所有文件

以下代码用于列举指定存储空间下的所有文件：

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using Aliyun.OSS;
// 初始化OssClient。
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
// 列举所有文件。
public void ListObject(string bucketName)
{
    try
    {
        ObjectListing result = null;
        string nextMarker = string.Empty;
        do
        {
            // 每页列举的文件个数通过maxKeys指定，超过指定数将进行分页显示。
            var listObjectsRequest = new ListObjectsRequest(bucketName)
            {
                Marker = nextMarker,
                MaxKeys = 100
            };
            result = client.ListObjects(listObjectsRequest); 
            Console.WriteLine("File:");
            foreach (var summary in result.ObjectSummaries)
            {
                Console.WriteLine("Name:{0}", summary.Key);
            }
            nextMarker = result.NextMarker;
        } while (result.IsTruncated);
    }
    catch (Exception ex)
    {
        Console.WriteLine("List object failed. {0}", ex.Message);
    }
}