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Filesystem operations on Data Lake Storage Gen1 using the .NET SDK

  • Artikkeli

In this article, you learn how to perform filesystem operations on Data Lake Storage Gen1 using the .NET SDK. Filesystem operations include creating folders in a Data Lake Storage Gen1 account, uploading files, downloading files, etc.

For instructions on how to do account management operations on Data Lake Storage Gen1 using the .NET SDK, see Account management operations on Data Lake Storage Gen1 using .NET SDK.

Prerequisites

Create a .NET application

The code sample available on GitHub walks you through the process of creating files in the store, concatenating files, downloading a file, and deleting some files in the store. This section of the article walks you through the main parts of the code.

  1. In Visual Studio, select the File menu, New, and then Project.

  2. Choose Console App (.NET Framework), and then select Next.

  3. In Project name, enter CreateADLApplication, and then select Create.

  4. Add the NuGet packages to your project.

    1. Right-click the project name in the Solution Explorer and click Manage NuGet Packages.

    2. In the NuGet Package Manager tab, make sure that Package source is set to nuget.org. Also, make sure the Include prerelease check box is selected.

    3. Search for and install the following NuGet packages:

      • Microsoft.Azure.DataLake.Store - This article uses v1.0.0.
      • Microsoft.Rest.ClientRuntime.Azure.Authentication - This article uses v2.3.1.

      Close the NuGet Package Manager.

  5. Open Program.cs, delete the existing code, and then include the following statements to add references to namespaces.

    using System;
using System.IO;using System.Threading;
using System.Linq;
using System.Text;
using System.Collections.Generic;
using System.Security.Cryptography.X509Certificates; // Required only if you're using an Azure AD application created with certificates

using Microsoft.Rest;
using Microsoft.Rest.Azure.Authentication;
using Microsoft.Azure.DataLake.Store;
using Microsoft.IdentityModel.Clients.ActiveDirectory;

  6. Declare the variables as shown below, and provide the values for the placeholders. Also, make sure the local path and file name you provide here exist on the computer.

    namespace SdkSample
{
    class Program
    {
        private static string _adlsg1AccountName = "<DATA-LAKE-STORAGE-GEN1-NAME>.azuredatalakestore.net";
    }
}

In the remaining sections of the article, you can see how to use the available .NET methods to do operations such as authentication, file upload, etc.

Authentication

Create client object

The following snippet creates the Data Lake Storage Gen1 filesystem client object, which is used to issue requests to the service.

// Create client objects
AdlsClient client = AdlsClient.CreateClient(_adlsg1AccountName, adlCreds);

Create a file and directory

Add the following snippet to your application. This snippet adds a file and any parent directory that does not exist.

// Create a file - automatically creates any parent directories that don't exist
// The AdlsOutputStream preserves record boundaries - it does not break records while writing to the store

using (var stream = client.CreateFile(fileName, IfExists.Overwrite))
{
    byte[] textByteArray = Encoding.UTF8.GetBytes("This is test data to write.\r\n");
    stream.Write(textByteArray, 0, textByteArray.Length);

    textByteArray = Encoding.UTF8.GetBytes("This is the second line.\r\n");
    stream.Write(textByteArray, 0, textByteArray.Length);
}

Append to a file

The following snippet appends data to an existing file in Data Lake Storage Gen1 account.

// Append to existing file

using (var stream = client.GetAppendStream(fileName))
{
    byte[] textByteArray = Encoding.UTF8.GetBytes("This is the added line.\r\n");
    stream.Write(textByteArray, 0, textByteArray.Length);
}

Read a file

The following snippet reads the contents of a file in Data Lake Storage Gen1.

//Read file contents

using (var readStream = new StreamReader(client.GetReadStream(fileName)))
{
    string line;
    while ((line = readStream.ReadLine()) != null)
    {
        Console.WriteLine(line);
    }
}

Get file properties

The following snippet returns the properties associated with a file or a directory.

// Get file properties
var directoryEntry = client.GetDirectoryEntry(fileName);
PrintDirectoryEntry(directoryEntry);

The definition of the PrintDirectoryEntry method is available as part of the sample on GitHub.

Rename a file

The following snippet renames an existing file in a Data Lake Storage Gen1 account.

// Rename a file
string destFilePath = "/Test/testRenameDest3.txt";
client.Rename(fileName, destFilePath, true);

Enumerate a directory

The following snippet enumerates directories in a Data Lake Storage Gen1 account.

// Enumerate directory
foreach (var entry in client.EnumerateDirectory("/Test"))
{
    PrintDirectoryEntry(entry);
}

The definition of the PrintDirectoryEntry method is available as part of the sample on GitHub.

Delete directories recursively

The following snippet deletes a directory, and all its subdirectories, recursively.

// Delete a directory and all its subdirectories and files
client.DeleteRecursive("/Test");

Samples

Here are a few samples that show how to use the Data Lake Storage Gen1 Filesystem SDK.

See also

Next steps