OSS网页上传和断点续传（STSToken篇）

云帐号AccessKey拥有全部API访问权限，在客户端不要直接使用，会泄露ak信息，形成安全问题。因此使用STS方式（临时帐号权限）给客户端受权。

C#版获取STSToken

1、下载阿里SDK（aliyun-net-sdk-Core.dll和aliyun-net-sdk-Sts.dll）

下载地址：https://develop.aliyun.com/tools/sdk#/dotnet

2、把SDK引入项目，引用如下命名空间

using Aliyun.Acs.Core;
using Aliyun.Acs.Core.Http;
using Aliyun.Acs.Core.Profile;
using Aliyun.Acs.Core.Exceptions;
using Aliyun.Acs.Sts.Model.V20150401;

3、准备相关帐号和策略文件

region：OSS所属区域，好比cn-hangzhou（杭州）等
AccessKeyID
AccessKeySecret
RoleArn
policy

以上信息在OSS配置篇上有详细讲解，其中policy内容根据AliyunOSSTokenGeneratorRolePolicy角色的受权策略可得，能够保存为json文件

{
  "Statement": [
    {
      "Action": "oss:*",
      "Effect": "Allow",
      "Resource": "*"
    }
  ],
  "Version": "1"
}

4、C#获取STSTok的代码

        // GET: /STS/Token
        public ActionResult Token()
        {
            string region = "cn-hangzhou";
            string AccessKeyID = "LTAI5sruyeiwWDBx";
            string AccessKeySecret = "EpFKkoeenidFHYAs3iIHYisAw";
            string RoleArn = "acs:ram::163898893340737:role/aliyunosstokengeneratorrole";
            string roleSessionName = "alice-001";
            long durationSeconds = 3600;
            string PolicyFile = System.IO.File.ReadAllText(Request.MapPath("/policy.json"));
            try
            {
                // 建立一个 Aliyun Acs Client, 用于发起 OpenAPI 请求
                IClientProfile profile = DefaultProfile.GetProfile(region, AccessKeyID, AccessKeySecret);
                DefaultAcsClient client = new DefaultAcsClient(profile);
                // 建立一个 AssumeRoleRequest 并设置请求参数
                AssumeRoleRequest request = new AssumeRoleRequest();
                request.Method = MethodType.POST;
                request.RoleArn = RoleArn;
                request.RoleSessionName = roleSessionName;
                request.Policy = PolicyFile;
                request.DurationSeconds = durationSeconds;
                // 发起请求，并获得response
                AssumeRoleResponse stsResponse = client.GetAcsResponse(request);
                var Credentials = stsResponse.Credentials;
                //返回Token
                return Json(new
                {
                    status = 200,
                    AccessKeyId = Credentials.AccessKeyId,
                    AccessKeySecret = Credentials.AccessKeySecret,
                    Expiration = Credentials.Expiration,
                    SecurityToken = Credentials.SecurityToken
                }, JsonRequestBehavior.AllowGet);
            }
            catch (ClientException e)
            {
                return Content(e.Message);
            }
        }

使用/STS/Token便可获取STSToken，其结果示例为：

{"status":200,"AccessKeyId":"STS.NHvFVYDPf2dmTRiPCv5ujnTbh","AccessKeySecret":"EanhX5L1na3jTDBTGSGALqcYm9qrB8s997tynnB8BVWi","Expiration":"2018-09-18T15:14:10Z","SecurityToken":"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"}

到这里，获取STSToken即大功告成！！！