本文介绍如何在上传、下载文件时，通过在请求中携带x-oss-traffic-limit参数并设置限速值，以保证其他应用的正常带宽。

说明 有关单链接限速的使用场景及注意事项的更多信息，请参考开发指南的 单链接限速文档。

简单上传和下载限速

以下代码用于简单上传（PutObject）和下载文件（GetObject）时设置单链接限速：

using System.Text;
using Aliyun.OSS;
var endpoint = "<yourEndpoint>";
var accessKeyId = "<yourAccessKeyId>";
var accessKeySecret = "<yourAccessKeySecret>";
var bucketName = "<yourBucketName>";
var objectName = "<yourObjectName>";
var objectContent = "More than just cloud.";
// 创建OssClient实例。
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{
    byte[] binaryData = Encoding.ASCII.GetBytes(objectContent);
    MemoryStream requestContent = new MemoryStream(binaryData);
    // 上传文件限速100KB/s，即819200bit/s。
    var putRequest = new PutObjectRequest(bucketName, objectName, requestContent)
    {
        TrafficLimit = 100*1024*8
    };
    client.PutObject(putRequest);
    Console.WriteLine("Put object succeeded");

    // 下载文件限速100KB/s，即819200bit/s。
    var getRequest = new GetObjectRequest(bucketName, objectName)
    {
        TrafficLimit = 100 * 1024 * 8
    };
    var getResult = client.GetObject(getRequest);
    Console.WriteLine("Get object succeeded");
}
catch (Exception ex)
{
    Console.WriteLine("Put object failed, {0}", ex.Message);
}

使用签名URL方式上传和下载限速

以下代码用于使用签名URL方式上传、下载文件时设置单链接限速： 

using System.Text;
using Aliyun.OSS;
var endpoint = "<yourEndpoint>";
var accessKeyId = "<yourAccessKeyId>";
var accessKeySecret = "<yourAccessKeySecret>";
var bucketName = "<yourBucketName>";
var objectName = "<yourObjectName>";
var objectContent = "More than just cloud.";
// 创建OssClient实例。
var client = new OssClient(endpoint, accessKeyId, accessKeySecret);
try
{       
    // 生成上传签名URL。
    var generatePresignedUriRequest = new GeneratePresignedUriRequest(bucketName, objectName, SignHttpMethod.Put)
    {
        Expiration = DateTime.Now.AddHours(1),
    };

    // 限速100KB/s，即819200bit/s。
    generatePresignedUriRequest.AddQueryParam("x-oss-traffic-limit", "819200");

    var signedUrl = client.GeneratePresignedUri(generatePresignedUriRequest);
    // 使用签名URL上传文件。
    var buffer = Encoding.UTF8.GetBytes(objectContent);
    using (var ms = new MemoryStream(buffer))
    {
        client.PutObject(signedUrl, ms);
    }
    Console.WriteLine("Put object by signatrue succeeded. {0} ", signedUrl.ToString());


    var metadata = client.GetObjectMetadata(bucketName, objectName);
    var etag = metadata.ETag;
    // 生成下载签名URL。
    // 限速100KB/s，即819200bit/s。
    var req = new GeneratePresignedUriRequest(bucketName, objectName, SignHttpMethod.Get);
    req.AddQueryParam("x-oss-traffic-limit", "819200");

    var uri = client.GeneratePresignedUri(req);
    // 使用签名URL下载文件。
    OssObject ossObject = client.GetObject(uri);
    using (var file = File.Open(downloadFilename, FileMode.OpenOrCreate))
    {
        using (Stream stream = ossObject.Content)
        {
            int length = 4 * 1024;
            var buf = new byte[length];
            do
            {
                length = stream.Read(buf, 0, length);
                file.Write(buf, 0, length);
            } while (length != 0);
        }
    }
    Console.WriteLine("Get object by signatrue succeeded. {0} ", uri.ToString());
}
catch (Exception ex)
{
    Console.WriteLine("Put object failed, {0}", ex.Message);
}