即使我可以在DefinedTypes中看到该类，Assembly.CreateInstance仍返回null [英] Assembly.CreateInstance returning null even though I can see the class in DefinedTypes
问题描述
我使用以下方法加载新的Assembly并将类的实例创建到新的AppDomain中.
I use the following method to load a new Assembly and create an instance of a class into a new AppDomain.
private static object CreateInstanceFromBinary(AppDomain appDomain, string typeName)
{
Assembly entryAssembly = Assembly.GetEntryAssembly();
byte[] assemblyBinary = LoadAssemblyBinary();
Assembly loadedAssembly = appDomain.Load(assemblyBinary);
if (loadedAssembly != null)
{
return loadedAssembly.CreateInstance(typeName);
}
return null;
}
这样叫来的人.
AppDomain appDomain = AppDomain.CreateDomain(domainName);
appDomainHelper = CreateInstanceFromBinary(appDomain, typeof(MyClass).FullName) as MyClass;
查看loadedAssembly，我可以看到MyClass存在于DefinedTypes内部，并且其名称与typeName相匹配.但是，当代码运行时
Looking into the loadedAssembly I can see that MyClass exists inside of the DefinedTypes and it's name matches typeName. However, when the code runs
loadedAssembly.CreateInstance(typeName)
它返回null.
此代码有效，但是，我最近将该类移到了与调用该类相同的dll中，现在它开始返回null.
This code was working, however, I recently moved this class into the same dll as the one that calls it and now it has started returning null.
关于如何解决此问题的任何想法?
Any ideas on how to fix this?
对于一些简短的可复制代码，可以使用以下代码.在此代码中，ClassLibrary1将CopyLocal设置为false，然后将其作为EmbeddedResource包含在内，以模仿我在实时项目中的内容，以防万一.
For some short(ish) reproducible code you can use the following. In this code ClassLibrary1 has CopyLocal set to false and then included as an EmbeddedResource to mimic what I have in my live project in case that matters.
在ConsoleApplication1内部，我有程序.
using ClassLibrary1;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
namespace ConsoleApplication1
{
class Program
{
static Program()
{
AppDomain.CurrentDomain.AssemblyResolve += Resolve;
}
static void Main(string[] args)
{
WorkerClass workerClass = new WorkerClass();
workerClass.DoWork();
Console.WriteLine("\r\nPress enter to exit...");
Console.ReadLine();
}
static System.Reflection.Assembly Resolve(object sender, ResolveEventArgs args)
{
if (!args.Name.Contains(","))
{
return null;
}
List<string> rn = System.Reflection.Assembly.GetEntryAssembly().GetManifestResourceNames()
.Where(r => r.EndsWith(".dll", StringComparison.OrdinalIgnoreCase))
.ToList();
string assemblyName = rn.FirstOrDefault(r => r.EndsWith(args.Name.Substring(0, args.Name.IndexOf(",")) + ".dll"));
if (!String.IsNullOrEmpty(assemblyName))
{
using (Stream stream = System.Reflection.Assembly.GetEntryAssembly().GetManifestResourceStream(assemblyName))
{
byte[] assemblyBinary = new byte[stream.Length];
stream.Read(assemblyBinary, 0, assemblyBinary.Length);
System.Reflection.Assembly assembly = System.Reflection.Assembly.Load(assemblyBinary);
if (Environment.UserInteractive)
{
Console.WriteLine("Loaded Assembly: " + assembly.FullName);
}
return assembly;
}
}
if (Environment.UserInteractive)
{
Console.WriteLine($"** Failed to find an assembly with name: {args.Name} ** ");
}
return null;
}
}
}
在ClassLibrary1里面有WorkerClass.
Inside of ClassLibrary1 there is WorkerClass.
using System;
namespace ClassLibrary1
{
public class WorkerClass
{
public void DoWork()
{
try
{
HelperClass hc = HelperClass.Create("Name");
Console.WriteLine("Created");
}
catch (Exception ex)
{
Console.WriteLine("Failed to create: " + ex.ToString());
}
}
}
}
和HelperClass.
and HelperClass.
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Security.Permissions;
namespace ClassLibrary1
{
[Serializable]
public class HelperClass : MarshalByRefObject
{
public AppDomain Domain { get; private set; }
public HelperClass()
{
}
[SecurityPermission(SecurityAction.Demand, Flags = SecurityPermissionFlag.Infrastructure)]
public override object InitializeLifetimeService()
{
return null;
}
public static HelperClass Create(string domainName)
{
AppDomain appDomain = AppDomain.CreateDomain(domainName);
HelperClass helperClass = CreateInstanceFromBinary(appDomain, typeof(HelperClass).AssemblyQualifiedName) as HelperClass;
if (helperClass == null)
{
throw new Exception("Unable to create instance from binary resource.");
}
helperClass.Domain = appDomain;
return helperClass;
}
private static object CreateInstanceFromBinary(AppDomain appDomain, string typeName)
{
Assembly entryAssembly = Assembly.GetEntryAssembly();
IList<string> rn = entryAssembly.GetManifestResourceNames().Where(r => r.EndsWith(".dll")).ToList();
string assembly = rn.FirstOrDefault(r => r.EndsWith($"{typeof(HelperClass).Assembly.GetName().Name}.dll"));
if (!String.IsNullOrEmpty(assembly))
{
using (Stream stream = entryAssembly.GetManifestResourceStream(assembly))
{
byte[] assemblyBinary = new byte[stream.Length];
stream.Read(assemblyBinary, 0, assemblyBinary.Length);
Assembly loadedAssembly = appDomain.Load(assemblyBinary);
if (loadedAssembly != null)
{
return loadedAssembly.CreateInstance(typeName);
}
}
}
return null;
}
}
}
return loadedAssembly.CreateInstance(typeName);返回null的地方.
Where it is return loadedAssembly.CreateInstance(typeName); that returns null.
推荐答案
在函数public static HelperClass Create(string domainName)中，您将AssemblyQualifiedName作为要创建的类的类型.
In your function public static HelperClass Create(string domainName) you are passing the AssemblyQualifiedName as the type of the class to create.
我认为您只想传递类型名称，即:ClassLibrary1.HelperClass
I think you just want to pass the type name, ie: ClassLibrary1.HelperClass
//HelperClass helperClass = CreateInstanceFromBinary(appDomain, typeof(HelperClass).AssemblyQualifiedName) as HelperClass;
HelperClass helperClass = CreateInstanceFromBinary(appDomain, typeof(HelperClass).ToString()) as HelperClass;
我尝试了一些变体，每次传递Assembly Qualified Name都失败，只是类型名按预期工作.
I tried some variations, each time passing in the Assembly Qualified Name failed, just the type name worked as expected.
尝试尝试并失败:
// Do not work
var x = loadedAssembly.CreateInstance(typeName); //AssemblyQualifiedName
var loadedType = loadedAssembly.GetType(typeName); //AssemblyQualifiedName
// Work
var x = Activator.CreateInstance(typeof(HelperClass)); // Works
var x = loadedAssembly.CreateInstance("ClassLibrary1.HelperClass");
var loadedType = loadedAssembly.GetType("ClassLibrary1.HelperClass");
var x = Activator.CreateInstance(loadedType);
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