Question

我想动态地在当前项目的单独解决方案中使用来自不同项目的类。我认为解决方案是将dll加载到我的项目中。我使用以下代码完成我的任务并且它有效。

string dllPath = @"the path of my dll";
var DLL = Assembly.LoadFile(dllPath);
foreach (Type type in DLL.GetExportedTypes())
{
      if (type.Name == "targetClassName")
      {
          var c = Activator.CreateInstance(type);
          try
          {
              type.InvokeMember("myMethod", BindingFlags.InvokeMethod, null, c, new object[] { "Params" });
          }
          catch(Exception ex)
          {
             MessageBox.Show(ex.Message);
          }
          break;
      }
}

但是，我现在的问题是我想卸载dll，我无法做到，因为Assembly中没有卸载方法。我找到的解决方案是我必须使用AppDomain加载程序集然后卸载它。

现在这是我的主要问题。我一直在FileNotFoundException。这是我的代码：

public class ProxyDomain : MarshalByRefObject
{
    public Assembly GetAssembly(string assemblyPath)
    {
        try
        {
            return Assembly.LoadFrom(assemblyPath);
        }
        catch (Exception ex)
        {
            throw new InvalidOperationException(ex.Message);
        }
    }
}

private void BuildButton_Click(object sender, EventArgs e)
{
    string dllPath = @"DllPath";
    string dir = @"directory Path of the dll";
    AppDomainSetup domaininfo = new AppDomainSetup();
    domaininfo.ApplicationBase = System.Environment.CurrentDirectory;
    Evidence adevidence = AppDomain.CurrentDomain.Evidence;
    AppDomain domain = AppDomain.CreateDomain("MyDomain", adevidence, domaininfo);

    Type Domtype = typeof(ProxyDomain);
    var value = (ProxyDomain)domain.CreateInstanceAndUnwrap(
         Domtype.Assembly.FullName,
         Domtype.FullName);

    var DLL = value.GetAssembly(dllPath);

    // Then use the DLL object as before
}

最后一行是发出以下异常Could not load file or assembly 'dll, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The system cannot find the file specified.

我已经尝试了link的解决方案，但没有任何对我有用......我一直得到同样的例外。之后我想卸载域名，但是我无法解决加载dll的第一个问题。如何修复我的代码？

修改

当我将预期的dll复制到我项目的同一个bin文件夹中时，它可以正常工作。但是，我不想在我的项目中复制dll。有没有办法从路径加载它而不将其复制到我的bin文件夹？

Answer 1

您在代理域中定义GetAssembly方法，将加载的Assembly拉入主域。这使得整个概念毫无意义，因为即使您卸载代理域，您的主域最终也会被加载的程序集污染。

不要返回程序集，只需在代理域中使用它。如果要将某些信息推回到主域，则必须传递简单的可序列化类型（或从MarshalByRefObject派生的远程对象），以便主域保持干净。

这是你应该怎么做的：

// This class provides callbacks to the host app domain.
// This is optional, you need only if you want to send back some information
public class DomainHost : MarshalByRefObject
{
    // sends any object to the host. The object must be serializable
    public void SendDataToMainDomain(object data)
    {
        Console.WriteLine($"Hmm, some interesting data arrived: {data}");
    }

    // there is no timeout for host
    public override object InitializeLifetimeService() => null;
}

你的代理应该是这样的：

class AssemblyLoader : MarshalByRefObject
{
    private DomainHost host;

    public void Initialize(DomainHost host)
    {
        // store the remote host here so you will able to use it to send feedbacks
        this.host = host;
        host.SendData("I am just being initialized.")
    }

    // of course, if your job has some final result you can have a return value
    // and then you don't even may need the DomainHost.
    // But do not return any Type from the loaded dll (not mentioning the whole Assembly).
    public void DoWork()
    {
        host.SendData("Work started. Now I will load some dll.");
        // TODO: load and use dll
        host.SendData(42);

        host.SendData("Job finished.")
    }
}

用法：

var domain = AppDomain.CreateDomain("SandboxDomain");
var loader = (AssemblyLoader)domain.CreateInstanceAndUnwrap(typeof(AssemblyLoader).Assembly.FullName, typeod(AssemblyLoader).FullName);

// pass the host to the domain (again, this is optional; just for feedbacks)
loader.Initialize(new DomainHost());

// Start the work.
loader.DoWork();

// At the end, you can unload the domain
AppDomain.Unload(domain);

最后是FileNotFoundException本身：

在AppDomain中，您只能加载程序集，这些程序集位于主域的相同或子文件夹中。在设置对象中使用此代替Environment.CurrentDirectory：

var setup = new AppDomainSetup
{
    ApplicationBase = AppDomain.CurrentDomain.BaseDirectory,
    PrivateBinPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location)
};

如果您确实要从任何位置加载程序集，请将其加载为byte[]：

var dll = Assembly.Load(File.ReadAllBytes(fullPathToDll));

使用AppDomain将dll动态加载和卸载到我的项目中

1 个答案: