<PackageReference Include="Tencent.QCloud.Cos.Sdk" Version="5.4.*" />

dotnet add package Tencent.QCloud.Cos.Sdk

using COSXML;
using COSXML.Auth;
using COSXML.Model.Object;
using COSXML.Model.Bucket;
using COSXML.CosException;

//初始化 CosXmlConfig 
string appid = "1250000000";//设置腾讯云账户的账户标识 APPID
string region = "COS_REGION"; //设置一个默认的存储桶地域
CosXmlConfig config = new CosXmlConfig.Builder()
  .IsHttps(true)  //设置默认 HTTPS 请求
  .SetRegion(region)  //设置一个默认的存储桶地域
  .SetDebugLog(true)  //显示日志
  .Build();  //创建 CosXmlConfig 对象

public class CustomQCloudCredentialProvider : DefaultSessionQCloudCredentialProvider
{

  // 这里假设开始没有密钥，也可以用初始的临时密钥来初始化
  public CustomQCloudCredentialProvider(): base(null, null, 0L, null) {
    ;
  }

  public override void Refresh()
  {
    //... 首先通过腾讯云请求临时密钥
    string tmpSecretId = "SECRET_ID"; //"临时密钥 SecretId", 临时密钥生成和使用指引参见 https://www.tencentcloud.com/document/product/436/14048
    string tmpSecretKey = "SECRET_KEY"; //"临时密钥 SecretKey", 临时密钥生成和使用指引参见 https://www.tencentcloud.com/document/product/436/14048
    string tmpToken = "COS_TOKEN"; //"临时密钥 token", 临时密钥生成和使用指引参见 https://www.tencentcloud.com/document/product/436/14048
    long tmpStartTime = 1546860702;//临时密钥有效开始时间，精确到秒
    long tmpExpiredTime = 1546862502;//临时密钥有效截止时间，精确到秒
    // 调用接口更新密钥
    SetQCloudCredential(tmpSecretId, tmpSecretKey, 
      String.Format("{0};{1}", tmpStartTime, tmpExpiredTime), tmpToken);
  }
}

QCloudCredentialProvider cosCredentialProvider = new CustomQCloudCredentialProvider();

string tmpSecretId = "SECRET_ID"; //"临时密钥 SecretId";
string tmpSecretKey = "SECRET_KEY"; //"临时密钥 SecretKey";
string tmpToken = "COS_TOKEN"; //"临时密钥 token";
long tmpExpireTime = 1546862502;//临时密钥有效截止时间，精确到秒
QCloudCredentialProvider cosCredentialProvider = new DefaultSessionQCloudCredentialProvider(
  tmpSecretId, tmpSecretKey, tmpExpireTime, tmpToken);

string secretId = Environment.GetEnvironmentVariable("SECRET_ID"); //用户的 SecretId，建议使用子账号密钥，授权遵循最小权限指引，降低使用风险。子账号密钥获取可参见 https://www.tencentcloud.com/document/product/598/32675
string secretKey = Environment.GetEnvironmentVariable("SECRET_KEY"); //用户的 SecretKey，建议使用子账号密钥，授权遵循最小权限指引，降低使用风险。子账号密钥获取可参见 https://www.tencentcloud.com/document/product/598/32675
long durationSecond = 600;  //每次请求签名有效时长，单位为秒
QCloudCredentialProvider cosCredentialProvider = new DefaultQCloudCredentialProvider(
  secretId, secretKey, durationSecond);

CosXml cosXml = new CosXmlServer(config, cosCredentialProvider);

try
{
  string bucket = "examplebucket-1250000000"; //格式：BucketName-APPID
  PutBucketRequest request = new PutBucketRequest(bucket);
  //执行请求
  PutBucketResult result = cosXml.PutBucket(request);
  //请求成功
  Console.WriteLine(result.GetResultInfo());
}
catch (COSXML.CosException.CosClientException clientEx)
{
  //请求失败
  Console.WriteLine("CosClientException: " + clientEx);
}
catch (COSXML.CosException.CosServerException serverEx)
{
  //请求失败
  Console.WriteLine("CosServerException: " + serverEx.GetInfo());
}

try
{
  GetServiceRequest request = new GetServiceRequest();
  //执行请求
  GetServiceResult result = cosXml.GetService(request);
  //得到所有的 buckets
  List<ListAllMyBuckets.Bucket> allBuckets = result.listAllMyBuckets.buckets;
}
catch (COSXML.CosException.CosClientException clientEx)
{
  //请求失败
  Console.WriteLine("CosClientException: " + clientEx);
}
catch (COSXML.CosException.CosServerException serverEx)
{
  //请求失败
  Console.WriteLine("CosServerException: " + serverEx.GetInfo());
}

// 初始化 TransferConfig
TransferConfig transferConfig = new TransferConfig();

// 初始化 TransferManager
TransferManager transferManager = new TransferManager(cosXml, transferConfig);

String bucket = "examplebucket-1250000000"; //存储桶，格式：BucketName-APPID
String cosPath = "exampleobject"; //对象在存储桶中的位置标识符，即称对象键
String srcPath = @"temp-source-file";//本地文件绝对路径

// 上传对象
COSXMLUploadTask uploadTask = new COSXMLUploadTask(bucket, cosPath);
uploadTask.SetSrcPath(srcPath);

uploadTask.progressCallback = delegate (long completed, long total)
{
    Console.WriteLine(String.Format("progress = {0:##.##}%", completed * 100.0 / total));
};

try {
  COSXML.Transfer.COSXMLUploadTask.UploadTaskResult result = await 
    transferManager.UploadAsync(uploadTask);
  Console.WriteLine(result.GetResultInfo());
  string eTag = result.eTag;
} catch (Exception e) {
    Console.WriteLine("CosException: " + e);
}

try
{
  string bucket = "examplebucket-1250000000"; //格式：BucketName-APPID
  GetBucketRequest request = new GetBucketRequest(bucket);
  //执行请求
  GetBucketResult result = cosXml.GetBucket(request);
  //bucket的相关信息
  ListBucket info = result.listBucket;
  if (info.isTruncated) {
    // 数据被截断，记录下数据下标
    this.nextMarker = info.nextMarker;
  }
}
catch (COSXML.CosException.CosClientException clientEx)
{
  //请求失败
  Console.WriteLine("CosClientException: " + clientEx);
}
catch (COSXML.CosException.CosServerException serverEx)
{
  //请求失败
  Console.WriteLine("CosServerException: " + serverEx.GetInfo());
}

// 初始化 TransferConfig
TransferConfig transferConfig = new TransferConfig();

// 初始化 TransferManager
TransferManager transferManager = new TransferManager(cosXml, transferConfig);

String bucket = "examplebucket-1250000000"; //存储桶，格式：BucketName-APPID
String cosPath = "exampleobject"; //对象在存储桶中的位置标识符，即称对象键
string localDir = System.IO.Path.GetTempPath();//本地文件夹
string localFileName = "my-local-temp-file"; //指定本地保存的文件名

// 下载对象
COSXMLDownloadTask downloadTask = new COSXMLDownloadTask(bucket, cosPath, 
  localDir, localFileName);

downloadTask.progressCallback = delegate (long completed, long total)
{
    Console.WriteLine(String.Format("progress = {0:##.##}%", completed * 100.0 / total));
};

try {
  COSXML.Transfer.COSXMLDownloadTask.DownloadTaskResult result = await 
    transferManager.DownloadAsync(downloadTask);
  Console.WriteLine(result.GetResultInfo());
  string eTag = result.eTag;
} catch (Exception e) {
    Console.WriteLine("CosException: " + e);
}

try
{
  string bucket = "examplebucket-1250000000"; //存储桶，格式：BucketName-APPID
  string key = "exampleobject"; //对象键
  DeleteObjectRequest request = new DeleteObjectRequest(bucket, key);
  //执行请求
  DeleteObjectResult result = cosXml.DeleteObject(request);
  //请求成功
  Console.WriteLine(result.GetResultInfo());
}
catch (COSXML.CosException.CosClientException clientEx)
{
  //请求失败
  Console.WriteLine("CosClientException: " + clientEx);
}
catch (COSXML.CosException.CosServerException serverEx)
{
  //请求失败
  Console.WriteLine("CosServerException: " + serverEx.GetInfo());
}