openread()没有读取所有数据

本文关键字：读取 数据 openread | 更新日期: 2023-09-27 18:04:29

对于windows Azure存储客户端库，CloudBlob.OpenRead()方法仅读取4mb的数据。如何使用OpenRead方法读取完整流。

CloudBlob blob = container.GetBlobReference(filename);
Stream stream = blob.OpenRead();

我必须使用OpenRead方法。不能使用DownloadToFile或DownloadToStream.

编辑:

在我的作用域之外的消费者代码调用

stream.CopyTo(readIntoStream);

CopyTo是一个扩展方法。

public static int CopyTo(this Stream source, Stream destination)
        {
            byte[] buffer = new byte[BUFFER_SIZE];
            int bytesRead;
            int bytesCopied = 0;
            do
            {
                bytesRead = source.Read(buffer, 0, BUFFER_SIZE);
                if (bytesRead > 0)
                    destination.Write(buffer, 0, bytesRead);
                bytesCopied += bytesRead;
            }
            while (bytesRead > 0);
            return bytesCopied;
        }

EDIT 2:

我观察到，当文件使用blob. uploadtext()方法上传时，它工作得很好，但是当blob使用OpenWrite方法上传时，如以下代码样例所做，OpenRead方法仅读取4194304字节(4mb)。

using(var input = File.OpenRead(@"C:'testFile.txt")) //5000000 bytes
using (var output = blob.OpenWrite())
{
       input.CopyTo(output);
}

EDIT:

在我的结尾产生问题的完整代码。

 static void Main(string[] args)
    {
        var blobContainer = GetContainer("tier1");
        blobContainer.CreateIfNotExist();
        var containerPermissions = new BlobContainerPermissions();
        containerPermissions.PublicAccess = BlobContainerPublicAccessType.Blob;
        blobContainer.SetPermissions(containerPermissions);
        var blob = blobContainer.GetBlobReference("testfileWithOpenWrite1.txt");
        using (var input = File.OpenRead(@"C:'testFile.txt")) //5000000 bytes
        using (var output = blob.OpenWrite(new BlobRequestOptions()))
            input.CopyTo(output);
        Console.WriteLine("uploaded");
        int bytesDownloaded = 0;
        byte[] buffer = new byte[65536];
        using (BlobStream bs = blob.OpenRead())
        {
            int chunkLength;
            do
            {
                chunkLength = bs.Read(buffer, 0, buffer.Length);
                bytesDownloaded += chunkLength;
            } while (chunkLength > 0);
        }
        Console.WriteLine(bytesDownloaded);
    }
    public static int CopyTo(this Stream source, Stream destination)
    {
        int BUFFER_SIZE = 65536;
        byte[] buffer = new byte[BUFFER_SIZE];
        int bytesRead;
        int bytesCopied = 0;
        do
        {
            bytesRead = source.Read(buffer, 0, BUFFER_SIZE);
            if (bytesRead > 0)
                destination.Write(buffer, 0, bytesRead);
            bytesCopied += bytesRead;
        }
        while (bytesRead > 0);
        return bytesCopied;
    }

EDIT 4 - Conclusion:

这可能是SDK v1.2附带的Microsoft.WindowsAzure.StorageClient.dll(程序集版本6.0.6002.17043)中的错误。它适用于最新的Microsoft.WindowsAzure.StorageClient.dll(程序集版本6.0.6002.18312 - SDK v1.4)。

谢谢smarx:)

openread()没有读取所有数据

我无法重现你所看到的。事情似乎如预期的那样运行:

static void Main(string[] args)
{
    // I also tried a real cloud storage account. Same result.
    var container = CloudStorageAccount.DevelopmentStorageAccount.CreateCloudBlobClient().GetContainerReference("testcontainer");
    container.CreateIfNotExist();
    var blob = container.GetBlobReference("testblob.txt");
    blob.UploadText(new String('x', 5000000));
    var source = blob.OpenRead();
    int BUFFER_SIZE = 4000000;
    byte[] buffer = new byte[BUFFER_SIZE];
    int bytesRead;
    int bytesCopied = 0;
    do
    {
        bytesRead = source.Read(buffer, 0, BUFFER_SIZE);
        bytesCopied += bytesRead;
    } while (bytesRead > 0);
    Console.WriteLine(bytesCopied); // prints 5000000
}
编辑:

我也(作为对编辑问题的回应)现在尝试使用OpenWrite上传blob，结果是相同的。(我拿回了一整团。)我使用以下代码代替blob.UploadText(…):

using (var input = File.OpenRead(@"testblob.txt")) //5000000 bytes
using (var output = blob.OpenWrite())
{
    input.CopyTo(output);
}

最后的WriteLine仍然打印5000000。

编辑2:

这有点烦了。将BUFFER_SIZE更改为65536不会改变任何东西。结果在我看来仍然是正确的。下面是我的完整的比较应用程序:

static void Main(string[] args)
{
    // I also tried a real cloud storage account. Same result.
    var container = CloudStorageAccount.DevelopmentStorageAccount.CreateCloudBlobClient().GetContainerReference("testcontainer");
    container.CreateIfNotExist();
    var blob = container.GetBlobReference("testblob.txt");
    using (var input = File.OpenRead(@"testblob.txt")) //5000000 bytes
    using (var output = blob.OpenWrite())
    {
        input.CopyTo(output);
    }
    var source = blob.OpenRead();
    int BUFFER_SIZE = 65536;
    byte[] buffer = new byte[BUFFER_SIZE];
    int bytesRead;
    int bytesCopied = 0;
    do
    {
        bytesRead = source.Read(buffer, 0, BUFFER_SIZE);
        bytesCopied += bytesRead;
    } while (bytesRead > 0);
    Console.WriteLine(bytesCopied); // prints 5000000
}
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