Question

是否有使用HTTP将文件下载到本地目录的内置方法？

我可以支持wget或编写自定义任务，但我想确保没有现成的方法来完成此任务。

提前致谢！

Answer 1

在MSBuild 4.0中，您可以使用内联任务来避免需要在单独的程序集中编译和部署自定义任务。

  <UsingTask TaskName="DownloadFile" TaskFactory="CodeTaskFactory" AssemblyFile="$(MSBuildToolsPath)\Microsoft.Build.Tasks.v4.0.dll">
    <ParameterGroup>
      <Address ParameterType="System.String" Required="true"/>
      <FileName ParameterType="System.String" Required="true" />
    </ParameterGroup>
    <Task>
      <Reference Include="System" />
      <Code Type="Fragment" Language="cs">
        <![CDATA[
            new System.Net.WebClient().DownloadFile(Address, FileName);
        ]]>
      </Code>
    </Task>
  </UsingTask>

  <Target Name="DownloadSomething">
    <DownloadFile Address="http://somewebsite/remotefile" FileName="localfilepath" />
  </Target>

Answer 2

MSBuild Community Tasks有一个WebDownload任务，似乎就是你需要的。

Answer 3

如果您尝试下载需要身份验证的文件（例如TFS Web或连接到域的IIS服务器），则MSBuild扩展包和MSBuild社区任务似乎都无法提供用户名或HTTP服务器的密码。在这种情况下，我最终编写了一个自定义的MSBuild任务。这就是我所做的。

我遵循Stack Overflow用户Doug的建议，在他对Download a file which requires authentication using vb.net/c#?的回答中，他建议将一些代码添加到Tom Archer在Code Guru网站上编写的方法中。

因此，我使用MS Visual Studio 2010创建了一个新的C＃项目，其中包含以下代码，用于创建名为Wget的MSBuild目标（显示完整源代码）：

// Include references to the following frameworks in your solution:
// - Microsoft.Build.Framework
// - Microsoft.Build.Utilities.v4.0
// - System
// - System.Net

using System;
using System.Net;
using System.IO;

using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;

namespace Wget
{
    public class Wget: Task
    {
        [Required]
        public String Address // HTTP address to access
        { get; set; }

        [Required]
        public String LocalFilename // Local file to which the downloaded page will be saved
        { get; set; }

        public String Username // Credential for HTTP authentication
        { get; set; }

        public String Password // Credential for HTTP authentication
        { get; set; }

        public override bool Execute()
        {
            int read = DownloadFile(Address, LocalFilename, Username, Password);

            Console.WriteLine("{0} bytes written", read);

            return true;
        }

        public static int DownloadFile(String remoteFilename, String localFilename, String httpUsername, String httpPassword)
        {
            // Function will return the number of bytes processed
            // to the caller. Initialize to 0 here.
            int bytesProcessed = 0;

            // Assign values to these objects here so that they can
            // be referenced in the finally block
            Stream remoteStream = null;
            Stream localStream = null;
            WebResponse response = null;

            // Use a try/catch/finally block as both the WebRequest and Stream
            // classes throw exceptions upon error
            try
            {
                // Create a request for the specified remote file name
                WebRequest request = WebRequest.Create(remoteFilename);
                if (request != null)
                {
                    // If a username or password have been given, use them
                    if (httpUsername.Length > 0 || httpPassword.Length > 0)
                    {
                        string username = httpUsername;
                        string password = httpPassword;
                        request.Credentials = new System.Net.NetworkCredential(username, password);
                    }

                    // Send the request to the server and retrieve the
                    // WebResponse object 
                    response = request.GetResponse();
                    if (response != null)
                    {
                        // Once the WebResponse object has been retrieved,
                        // get the stream object associated with the response's data
                        remoteStream = response.GetResponseStream();

                        // Create the local file
                        localStream = File.Create(localFilename);

                        // Allocate a 1k buffer
                        byte[] buffer = new byte[1024];
                        int bytesRead;

                        // Simple do/while loop to read from stream until
                        // no bytes are returned
                        do
                        {
                            // Read data (up to 1k) from the stream
                            bytesRead = remoteStream.Read(buffer, 0, buffer.Length);

                            // Write the data to the local file
                            localStream.Write(buffer, 0, bytesRead);

                            // Increment total bytes processed
                            bytesProcessed += bytesRead;
                        } while (bytesRead > 0);
                    }
                }
            }
            catch (Exception e)
            {
                Console.WriteLine(e.Message);
            }
            finally
            {
                // Close the response and streams objects here 
                // to make sure they're closed even if an exception
                // is thrown at some point
                if (response != null) response.Close();
                if (remoteStream != null) remoteStream.Close();
                if (localStream != null) localStream.Close();
            }

            // Return total bytes processed to caller.
            return bytesProcessed;
        }
    }
}

有了这个，我可以将以下任务添加到我的MSBuild项目中：

<!-- Get the contents of a Url-->
<Wget
    Address="http://mywebserver.com/securepage"
    LocalFilename="mydownloadedfile.html"
    Username="myusername"
    Password="mypassword">
</Wget>

Wget任务下载mywebserver.com提供的页面，并使用用户名“myusername”和密码“mypassword”将其保存到当前工作目录中的文件mydownloadedfile.html。

但是，为了使用自定义Wget MSBuild任务，我必须告诉MSBuild在哪里找到Wget程序集文件（.dll）。这是通过MSBuild的元素完成的：

<!-- Import your custom MSBuild task -->
<UsingTask AssemblyFile="MyCustomMSBuildTasks\Wget\bin\Release\Wget.dll" TaskName="Wget" />

如果你想获得幻想，你甚至可以让你的MSBuild项目在调用之前构建Wget。为此，使用<MSBuild Projects>任务构建解决方案，并使用<UsingTaks AssemblyFile>任务导入它，如下所示：

<!-- Build the custom MSBuild target solution-->
<MSBuild Projects="MyCustomMSBuildTasks\CustomBuildTasks.sln" Properties="Configuration=Release" />

<!-- Import your custom MSBuild task -->
<UsingTask AssemblyFile="MyCustomMSBuildTasks\Wget\bin\Release\Wget.dll" TaskName="Wget" />

<!-- Get the contents of a Url-->
<Wget
    Address="http://mywebserver.com/securepage"
    LocalFilename="mydownloadedfile.html"
    Username="myusername"
    Password="mypassword">
</Wget>

如果您之前从未创建过自定义MSBuild目标，那么一旦您了解了基础知识，就不会太困难了。查看上面的C＃代码，查看官方MSDN文档，并在网上搜索更多示例。一个好的开始是：

http://msdn.microsoft.com/en-us/library/t9883dzc.aspx

Answer 4

DownloadFile任务在MSBuild 15.8及更高版本中可用（自2018年8月14日起）

示例：

    <PropertyGroup>  
      <LicenceUrl>https://raw.githubusercontent.com/Microsoft/msbuild/master/LICENSE</LicenceUrl>
    </PropertyGroup>  

    <Target Name="DownloadContentFiles" BeforeTargets="Build">
        <DownloadFile
            SourceUrl="$(LicenceUrl)"
            DestinationFolder="$(MSBuildProjectDirectory)">
        <Output TaskParameter="DownloadedFile" ItemName="Content" />
      </DownloadFile>
    </Target>

有关更多详细信息：DownloadFile task

Answer 5

除了MSBuild社区任务项目中的WebDownload任务外，MSBuild扩展包（当前版本：4.x）还有一个WebClient类，可用于下载文件。您可以在此处下载MSBuild扩展包：

http://msbuildextensionpack.codeplex.com

以下是使用MSBuild Extension Pack 4下载文件的示例：

<Project ToolsVersion="4.0" DefaultTargets="Default" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<PropertyGroup>
    <TPath>$(MSBuildProjectDirectory)\..\MSBuild.ExtensionPack.tasks</TPath>
    <TPath Condition="Exists('$(MSBuildProjectDirectory)\..\..\Common\MSBuild.ExtensionPack.tasks')">$(MSBuildProjectDirectory)\..\..\Common\MSBuild.ExtensionPack.tasks</TPath>
</PropertyGroup>
<Import Project="$(TPath)"/>
<Target Name="Default">
    <!-- Download a File-->
    <MSBuild.ExtensionPack.Web.WebClient TaskAction="DownloadFile" Url="http://hlstiw.bay.livefilestore.com/y1p7GhsJWeF4ig_Yb-8QXeA1bL0nY_MdOGaRQ3opRZS0YVvfshMfoZYe_cb1wSzPhx4nL_yidkG8Ji9msjRcTt0ew/Team%20Build%202008%20DeskSheet%202.0.pdf?download" FileName="C:\TFS Build 2008 DeskSheet.pdf"/>
    <!-- Get the contents of a Url-->
    <MSBuild.ExtensionPack.Web.WebClient TaskAction="OpenRead" Url="http://www.msbuildextensionpack.com">
        <Output TaskParameter="Data" PropertyName="Out"/>
    </MSBuild.ExtensionPack.Web.WebClient>
    <Message Text="$(Out)"/>
</Target>

正如其他答案所述，WebClient似乎无法从安全（受密码保护的）网络服务器下载。

如何使用msbuild下载文件？

5 个答案: