[英]How to load an assembly as reflection-only in a new AppDomain?
I'm experienced in C# but relatively unfamiliar with the concepts of AppDomain
and the like.我在 C# 方面有经验,但对AppDomain
等概念相对不熟悉。 Anyway, I'm trying to get an assembly to load in a reflection-only context so I can grab all of its namespaces.无论如何,我正在尝试让程序集加载到仅反射上下文中,以便我可以获取其所有名称空间。 Here is the code I have right now (warning: PowerShell):这是我现在拥有的代码(警告:PowerShell):
function Get-Namespaces($assembly)
{
$assemblyClass = [Reflection.Assembly]
$winmdClass = [Runtime.InteropServices.WindowsRuntime.WindowsRuntimeMetadata]
$domain = [AppDomain]::CurrentDomain
# Since desktop .NET can't work with winmd files,
# we have to use the reflection-only APIs and preload
# all the dependencies manually.
$appDomainHandler =
{
Param($sender, $e);
$assemblyClass::ReflectionOnlyLoad($e.Name)
}
$winmdHandler =
{
Param($sender, $e)
[string[]] $empty = @()
$path = $winmdClass::ResolveNamespace($e.NamespaceName, $empty) | select -Index 0
$e.ResolvedAssemblies.Add($assemblyClass::ReflectionOnlyLoadFrom($path))
}
# Hook up the handlers
$domain.add_ReflectionOnlyAssemblyResolve($appDomainHandler)
$winmdClass::add_ReflectionOnlyNamespaceResolve($winmdHandler)
# Do the actual work
$assemblyObject = $assemblyClass::ReflectionOnlyLoadFrom($assembly)
$types = $assemblyObject.GetTypes()
$namespaces = $types | ? IsPublic | select Namespace -Unique
# Deregister the handlers
$domain.remove_ReflectionOnlyAssemblyResolve($appDomainHandler)
$winmdClass::remove_ReflectionOnlyNamespaceResolve($winmdHandler)
return $namespaces
}
For some reason, when I'm running the function on assemblies like System.Xaml
or WindowsBase
I'm getting these errors:出于某种原因,当我在System.Xaml
或WindowsBase
等程序集上运行该函数时,出现以下错误:
Exception calling "ReflectionOnlyLoadFrom" with "1" argument(s): "API restriction: The assembly 'file:///C:\Program Files (x86)\Reference Assemblies\Microsoft\ Framework\.NETFramework\v4.6.1\System.Xaml.dll' has already loaded from a different location. It cannot be loaded from a new location within the same appdomain." At C:\Users\James\Code\csharp\Shims.Xaml\generate.ps1:50 char:5 + $assemblyObject = $assemblyClass::ReflectionOnlyLoadFrom($assembl ... + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : NotSpecified: (:) [], MethodInvocationException + FullyQualifiedErrorId : FileLoadException
So what I'd like to know is, how can I load the assembly in a new AppDomain?所以我想知道的是,如何在新的 AppDomain 中加载程序集? I checked MSDN but all I can find are methods like CreateInstanceAndUnwrap
, which I can't/don't want to do since this is reflection-only.我检查了MSDN,但我能找到的只有CreateInstanceAndUnwrap
类的方法,我不能/不想这样做,因为这只是反射。
TL;DR: How can I load assemblies in a reflection-only context in a new AppDomain? TL;DR:如何在新 AppDomain 的仅反射上下文中加载程序集? Both C# and PowerShell code samples welcome.欢迎使用 C# 和 PowerShell 代码示例。
EDIT: Here is a GitHub gist of the script I've made, so others can repro the error/test changes.编辑:这是我制作的脚本的 GitHub 要点,因此其他人可以重现错误/测试更改。
I got the same exception when loading multiple assemblies for different target frameworks, but with the same identity.为不同的目标框架加载多个程序集时,我遇到了相同的异常,但具有相同的身份。 My workaround was to do the assembly load in a separate .ps1, and call it via CMD /C
, which creates a new AppDomain for each script call, thereby avoiding the exception.我的解决方法是在单独的 .ps1 中执行程序集加载,并通过CMD /C
调用它,这会为每个脚本调用创建一个新的 AppDomain,从而避免异常。
Parent *.ps1:父 *.ps1:
& CMD /C powershell.exe -NoProfile -ExecutionPolicy Bypass -File "$PsScriptRoot\check-assembly.ps1" "net461\MyAssembly.dll"
# Check exit code...
& CMD /C powershell.exe -NoProfile -ExecutionPolicy Bypass -File "$PsScriptRoot\check-assembly.ps1" "netcoreapp3.1\MyAssembly.dll"
# Check exit code...
check-assembly.ps1:检查-assembly.ps1:
Param(
[Parameter(Mandatory, HelpMessage="DLL file to check: ")]
[string]$dllFile
)
$ass = [System.Reflection.Assembly]::LoadFrom("$dllFile")
# Check $ass
I think I've got it:我想我已经明白了:
function Load-AssemblyInNewAppDomain($assembly)
{
$domain = [AppDomain]::CreateDomain("foo")
$domain.DoCallback
({
$loaded = [Reflection.Assembly]::Load($assembly)
})
}
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