blob 和 sas

Blob是什么？

请看上篇文章简单总结下关于blob的图片上传在使用Blob图片上传的时候碰到许多问题，比如如何使用用户名密码下载文件啊什么的今天就记录一下我碰到的最大的问题

如何匿名去访问你上传的Blob文件

共享访问签名：了解 SAS 模型这篇文章值得一看，多数官方的文档在有时候还是很有用的。尝试了半天，只发现一个方法可以用，使用blobName来生成SAS，再通过SAS生成的Uri+SASToken来访问blob文件。

 1   private static string GetBlobSasUri(CloudBlobContainer container, string blobName, string policyName = null)
 2         {
 3             string sasBlobToken;
 4 
 5             CloudBlockBlob blob = container.GetBlockBlobReference(blobName);
 6 
 7             if (policyName == null)
 8             {
 9                 SharedAccessBlobPolicy adHocSAS = new SharedAccessBlobPolicy()
10                 {
11                     SharedAccessExpiryTime = DateTime.UtcNow.AddMinutes(1),
12                     Permissions = SharedAccessBlobPermissions.Read | SharedAccessBlobPermissions.Write | SharedAccessBlobPermissions.Create
13                 };
14 
15                 sasBlobToken = blob.GetSharedAccessSignature(adHocSAS);
16 
17                 Console.WriteLine("SAS for blob (ad hoc): {0}", sasBlobToken);
18                 Console.WriteLine();
19             }
20             else
21             {
22                 sasBlobToken = blob.GetSharedAccessSignature(null, policyName);
23 
24                 Console.WriteLine("SAS for blob (stored access policy): {0}", sasBlobToken);
25                 Console.WriteLine();
26             }
27 
28             return blob.Uri + sasBlobToken;
29         }

其实官方文档写的很详细了，不过有个参数我不是很懂，policyName ，文档里也没有过多的介绍，不过从代码来看，应该是已知URI，生成token后拼接吧。嗯。。。有空测试一下就知道了。。

官方还有一个比较吸引我的方法

 1 private static string GetContainerSasUri(CloudBlobContainer container, string storedPolicyName = null)
 2         {
 3             string sasContainerToken;
 4 
 5             if (storedPolicyName == null)
 6             {
 7                 SharedAccessBlobPolicy adHocPolicy = new SharedAccessBlobPolicy()
 8                 {
 9                     SharedAccessExpiryTime = DateTime.UtcNow.AddHours(24),
10                     Permissions = SharedAccessBlobPermissions.Write | SharedAccessBlobPermissions.List
11                 };
12 
13                 sasContainerToken = container.GetSharedAccessSignature(adHocPolicy, null);
14 
15                 Console.WriteLine("SAS for blob container (ad hoc): {0}", sasContainerToken);
16                 Console.WriteLine();
17             }
18             else
19             {
20                 sasContainerToken = container.GetSharedAccessSignature(null, storedPolicyName);
21 
22                 Console.WriteLine("SAS for blob container (stored access policy): {0}", sasContainerToken);
23                 Console.WriteLine();
24             }
25 
26             return container.Uri + sasContainerToken;
27         }

可以直接定位到容器，在容器上直接创建SAS来访问，然而我试了不同的参数，返回了各种各样的错误信息，比如。。

1 <Error>
2 <Code>AuthenticationFailed</Code>
3 <Message>
4 Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature. RequestId:2ce78f2c-0001-0023-1773-00b9e0000000 Time:2017-07-19T09:45:48.3088986Z
5 </Message>
6 <AuthenticationErrorDetail>
7 Signature did not match. String to sign used was wl 2017-07-20T09:45:12Z /blob/hollywoodsharestorage/$root 2016-05-31
8 </AuthenticationErrorDetail>
9 </Error>

1 <Error>
2 <Code>AuthenticationFailed</Code>
3 <Message>
4 Server failed to authenticate the request. Make sure the value of Authorization header is formed correctly including the signature. RequestId:4e04d8fe-0001-0020-6471-00bae7000000 Time:2017-07-19T09:29:23.1074413Z
5 </Message>
6 <AuthenticationErrorDetail>
7 Access without signed identifier cannot have time window more than 1 hour: Start [Wed, 19 Jul 2017 09:29:23 GMT] - Expiry [Wed, 19 Jul 2017 18:24:53 GMT]
8 </AuthenticationErrorDetail>
9 </Error>

差不多都是在告诉我，生成的签名不对。。。

是我打开的方式不对，还是有别的使用的方法，这个还需要更深一步研究，希望看到的各位大神，有知晓的，分享一下，感激不尽~