好的，我们必须澄清一些事情。首先，如果您希望能够在不锁定文件iteslf的情况下将dll加载和卸载到不同的AppDomain，也许您可以使用这样的方法：
AppDomain apd = AppDomain.CreateDomain("newdomain");
using(var fs = new FileStream("myDll.dll", FileMode.Open))
{
var bytes = new byte[fs.Length];
fs.Read(bytes, 0, bytes .Length);
Assembly loadedAssembly = apd.Load(bytes);
}
这样，您将不会锁定文件，并且您应该能够稍后卸载域，重新编译文件并稍后使用更新的版本加载它。但我不是 100% 确定这是否不会破坏您的应用程序。
那是因为第二件事。如果您将使用CreateInstanceAndUnwrap方法，根据 MSDN，您必须在两个 appdomains 中加载程序集 - 一个正在调用，另一个是您从中调用。当您在 AppDomains 中加载了两个不同的 dll 时，这可能会结束。
包含解包类的程序集必须加载到两个应用程序域中，但它可以加载仅存在于新应用程序域中的其他程序集。
我现在不记得了，但是我认为当您调用时，两个应用程序域中的对象创建行为会有所不同CreateInstanceAndUnwrap，但我不记得细节了。
对于您的插件架构，您可能需要阅读这篇博文。关于如何处理动态插件使用 AppDomain 类加载和卸载代码
编辑
我忘记了这个 AppDomains 是如何工作的，我可能会引入一些混乱。我准备了一个简短的例子，'插件'架构如何工作。它与我之前在博客中描述的非常相似，这是我使用影子复制的示例。如果由于某些原因您不想使用它，可以很容易地更改为使用AppDomain.Load(byte[] bytes)
我们有 3 个程序集，第一个是基本插件程序集，它将作为代理工作，并将加载到所有 AppDomains（在我们的例子中 - 在主应用程序域和插件应用程序域中）。
namespace PluginBaseLib
{
//Base class for plugins. It has to be delivered from MarshalByRefObject,
//cause we will want to get it's proxy in our main domain.
public abstract class MyPluginBase : MarshalByRefObject
{
protected MyPluginBase ()
{ }
public abstract void DrawingControl();
}
//Helper class which instance will exist in destination AppDomain, and which
//TransparentProxy object will be used in home AppDomain
public class MyPluginFactory : MarshalByRefObject
{
//This method will be executed in destination AppDomain and proxy object
//will be returned to home AppDomain.
public MyPluginBase CreatePlugin(string assembly, string typeName)
{
Console.WriteLine("Current domain: {0}", AppDomain.CurrentDomain.FriendlyName);
return (MyPluginBase) Activator.CreateInstance(assembly, typeName).Unwrap();
}
}
//Small helper class which will show how to call method in another AppDomain.
//But it can be easly deleted.
public class MyPluginsHelper
{
public static void LoadMyPlugins()
{
Console.WriteLine("----------------------");
Console.WriteLine("Loading plugins in following app domain: {0}", AppDomain.CurrentDomain.FriendlyName);
AppDomain.CurrentDomain.Load("SamplePlugin, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null");
Console.WriteLine("----------------------");
}
}
}
在这里，我们将有另一个带有我们的虚拟插件的程序集，称为 SamplePlugin.dll 并存储在“Plugins”文件夹下。它引用了 PluginBaseLib.dll
namespace SamplePlugin
{
public class MySamplePlugin : MyPluginBase
{
public MySamplePlugin()
{ }
public override void DrawingControl()
{
var color = Console.ForegroundColor;
Console.ForegroundColor = ConsoleColor.Green;
Console.WriteLine("----------------------");
Console.WriteLine("This was called from app domian {0}", AppDomain.CurrentDomain.FriendlyName );
Console.WriteLine("I have following assamblies loaded:");
foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies())
{
Console.WriteLine("\t{0}", assembly.GetName().Name);
}
Console.WriteLine("----------------------");
Console.ForegroundColor = color;
}
}
}
最后一个程序集（简单的控制台应用程序）将仅引用 PluginBaseLib.dll 和
namespace ConsoleApplication1
{
//'Default implementation' which doesn't use any plugins. In this sample
//it just lists the assemblies loaded in AppDomain and AppDomain name itself.
public static void DrawControlsDefault()
{
Console.WriteLine("----------------------");
Console.WriteLine("No custom plugin, default app domain {0}", AppDomain.CurrentDomain.FriendlyName);
Console.WriteLine("I have following assamblies loaded:");
foreach (var assembly in AppDomain.CurrentDomain.GetAssemblies())
{
Console.WriteLine("\t{0}", assembly.GetName().Name);
}
Console.WriteLine("----------------------");
}
class Program
{
static void Main(string[] args)
{
//Showing that we don't have any additional plugins loaded in app domain.
DrawControlsDefault();
var appDir = AppDomain.CurrentDomain.BaseDirectory;
//We have to create AppDomain setup for shadow copying
var appDomainSetup = new AppDomainSetup
{
ApplicationName = "", //with MSDN: If the ApplicationName property is not set, the CachePath property is ignored and the download cache is used. No exception is thrown.
ShadowCopyFiles = "true",//Enabling ShadowCopy - yes, it's string value
ApplicationBase = Path.Combine(appDir,"Plugins"),//Base path for new app domain - our plugins folder
CachePath = "VSSCache"//Path, where we want to have our copied dlls store.
};
var apd = AppDomain.CreateDomain("My new app domain", null, appDomainSetup);
//Loading dlls in new appdomain - when using shadow copying it can be skipped,
//in CreatePlugin method all required assemblies will be loaded internaly,
//Im using this just to show how method can be called in another app domain.
//but it has it limits - method cannot return any values and take any parameters.
//apd.DoCallBack(new CrossAppDomainDelegate(MyPluginsHelper.LoadMyPlugins));
//We are creating our plugin proxy/factory which will exist in another app domain
//and will create for us objects and return their remote 'copies'.
var proxy = (MyPluginFactory) apd.CreateInstance("PluginBaseLib", "PluginBaseLib.MyPluginFactory").Unwrap();
//if we would use here method (MyPluginBase) apd.CreateInstance("SamplePlugin", "SamplePlugin.MySamplePlugin").Unwrap();
//we would have to load "SamplePlugin.dll" into our app domain. We may not want that, to not waste memory for example
//with loading endless number of types.
var instance = proxy.CreatePlugin("SamplePlugin", "SamplePlugin.MySamplePlugin");
instance.DrawingControl();
Console.WriteLine("Now we can recompile our SamplePlugin dll, replace it in Plugin directory and load in another AppDomain. Click Enter when you ready");
Console.ReadKey();
var apd2 = AppDomain.CreateDomain("My second domain", null, appDomainSetup);
var proxy2 = (MyPluginFactory)apd2.CreateInstance("PluginBaseLib", "PluginBaseLib.MyPluginFactory").Unwrap();
var instance2 = proxy2.CreatePlugin("SamplePlugin", "SamplePlugin.MySamplePlugin");
instance2.DrawingControl();
//Now we want to prove, that this additional assembly was not loaded to prmiary app domain.
DrawControlsDefault();
//And that we still have the old assembly loaded in previous AppDomain.
instance.DrawingControl();
//App domain is unloaded so, we will get exception if we try to call any of this object method.
AppDomain.Unload(apd);
try
{
instance.DrawingControl();
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
Console.ReadKey();
}
}
}
影印似乎很方便。