在运行时加载NuGet依赖项 [英] Load NuGet dependencies at runtime

问题描述

我正在寻找一种通过执行以下步骤来运行代码的方法：

I'm looking for a way to run code by executing the following steps:

1. 接收NuGet软件包列表（列表元组（程序包名称，程序包版本，主类的路径）。


2. 在本地目录中检索它们（参见代码示例1）


3. 在运行时将它们加载到我的程序中


4. 通过自省运行主要类（参见代码示例2）

1. Receiving a list of NuGet packages (a list of tuples ("package name", "package version", "path to main class").
2. Retrieving them in a local directory (cf code sample #1)
3. Loading them in my program at run-time
4. Running the main classes by introspection (cf code sample #2)

现在，我正在为第三步苦苦挣扎。我找不到如何在运行时加载程序包的方法。

By now I am struggling with the third step. I can't find out how to load my package at run-time.

我的主要问题是：

• 如何找出检索到的软件包存储在哪个文件夹中？


• 如何将那些目录的内容加载到程序中？

代码示例1：

private static void getPackageByNameAndVersion(string packageID, string version)
{
    IPackageRepository repo =
            PackageRepositoryFactory.Default
                  .CreateRepository("https://packages.nuget.org/api/v2");

   string path = "C:/tmp_repo";
   PackageManager packageManager = new PackageManager(repo, path);
   Console.WriteLine("before dl pkg");
   packageManager.InstallPackage(packageID, SemanticVersion.Parse(version));

}

代码示例2：

private static void loadByAssemblyNameAndTypeName(string assemblyName, string typeName)
{
   AppDomain isolationAppDomain = AppDomain.CreateDomain("tmp");
   object a = isolationAppDomain.CreateInstanceAndUnwrap(assemblyName, typeName);
   Type x = a.GetType();
   MethodInfo m = x.GetMethod("Main");
   m.Invoke(a, new object[] { });
}

推荐答案

抢一杯咖啡： ）

正在下载nuget软件包吗？

Nuget.Core（nuget软件包）是一个不错的选择，在这里是我拥有的一小段代码，应该可以通过 id 和 version

Grab a cup of coffee :)

Downloading the nuget package?

Nuget.Core (nuget package) is a good choice, and here is a snippet of code that I have that should be able to download a nuget package by id and version

var repo = PackageRepositoryFactory.Default
                .CreateRepository("https://packages.nuget.org/api/v2");

string path = "c:\\temp";
var packageManager = new PackageManager(repo, path);
packageManager.PackageInstalled += PackageManager_PackageInstalled;

var package = repo.FindPackage("packageName", SemanticVersion.Parse("1.0.0"));
if (package != null)
{
    packageManager.InstallPackage(package, false, true);
}

请注意，我将事件处理程序插入了 PackageManager 类的 PackageInstalled 事件。

我们如何在隔离的应用程序域中加载程序集？

由于反射API无法提供在特定域中加载程序集的方法，我们将在我们的隔离域中创建一个充当加载程序的代理类：

How do we load an assembly in an isolated app domain?

Since reflection API does not provide a way to load an assembly in a specific domain, We will create a proxy class that act as a loader in our isolated domain:

public class TypeProxy : MarshalByRefObject
{
    public Type LoadFromAssembly(string assemblyPath, string typeName)
    {
        try
        {
            var asm = Assembly.LoadFile(assemblyPath);
            return asm.GetType(typeName);
        }
        catch (Exception) { return null; }
    }
}

现在，如何将所有内容整合在一起

这是复杂的部分：

And now, is how to put it all together?

Here comes the complex part:

private static void PackageManager_PackageInstalled(object sender, 
                                                    PackageOperationEventArgs e)
{
    var files = e.FileSystem.GetFiles(e.InstallPath, "*.dll", true);
    foreach (var file in files)
    {
        try
        {
            AppDomain domain = AppDomain.CreateDomain("tmp");
            Type typeProxyType = typeof(TypeProxy);
            var typeProxyInstance = (TypeProxy)domain.CreateInstanceAndUnwrap(
                    typeProxyType.Assembly.FullName,
                    typeProxyType.FullName);

            var type = typeProxyInstance.LoadFromAssembly(file, "<KnownTypeName>");
            object instance = 
                domain.CreateInstanceAndUnwrap(type.Assembly.FullName, type.FullName);
        }
        catch (Exception ex)
        {
            Console.WriteLine("failed to load {0}", file);
            Console.WriteLine(ex.ToString());
        }

    }
}

请注意，此方法是在下载nuget程序包后执行的事件处理程序

Notice that this method is the event handler that gets executed after downloading the nuget package

也

请注意，您需要将< KnownTypeName> 替换为来自程序集的预期类型名称（或者可能会发现程序集中的所有公共类型）

Note that you will need to replace <KnownTypeName> with the expected type name coming from the assembly (or maybe run a discovery of all public types in the assembly)

---

值得一提的是，我还没有亲自执行此代码，因此不能保证它会立即可用，仍然可能需要进行一些调整。但是希望它是可以解决问题的概念。

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