Activator.CreateInstance:无法从程序集中加载类型 [英] Activator.CreateInstance: Could not load type from assembly

问题描述

我正在尝试创建一个在我的项目中的插件 .dll 中实现的类的实例，以进行类型发现.我收到此异常:

<块引用>

无法从程序集中加载类型Action"'SquidReports.DataCollector.Plugin.BES，版本=1.0.0.0，文化=中性，PublicKeyToken=null'.

这是我正在使用的确切方法签名: 了解更多信息和此问题的常见解决方案.

...但它以成功加载结束，并且在正确的位置清楚地提到了我的程序集:

<块引用>

日志:正在尝试下载新的 URL 文件:///C:/Source/C#/SquidReports/SquidReports.DataCollector/bin/x86/Debug/SquidReports.DataCollector.Plugin.BES.DLL.

长命名版本的日志不包含可疑消息.

还有什么想法吗?

EDIT:这是 Action 类的最小定义.它纯粹是一个模型类.

public class Action : ICollectible{公共动作(){//空构造函数}公共动作(int actionID，字符串站点ID，字符串名称){this.ActionID = actionID;this.SiteID = 站点 ID；this.Name = 名称；}公共 int ID { 获取；放;}//DB分配的身份ID[钥匙]公共 int ActionID { 获取；放;}//API分配的身份ID公共字符串 SiteID { 获取；放;}公共字符串名称 { 获取；放;}}

ICollectible 接口和 [Key] 属性是另一个程序集的一部分.不确定这是否会产生影响?

编辑 2: 正如 Erik 在下面指出的那样，显然我也对这个 OTHER 程序集进行了完全相同的检查.

解决方案

正如您发现的，程序集正在加载，只是找不到类型 (Action).您必须指定类型的全名，Namespace.Action 以便 .NET 找到它.

I'm trying to create an instance of a class implemented in a plugin .dll in my project to do type discovery. I'm receiving this exception:

Could not load type 'Action' from assembly 'SquidReports.DataCollector.Plugin.BES, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null'.

This is the exact method signature I'm using: https://msdn.microsoft.com/en-us/library/d133hta4(v=vs.110).aspx

In other words, I'm attempting to spawn the object based on the Assembly name and the class name, like so:

object modelObject = Activator.CreateInstance((string)modelInfo.AssemblyName, (string)modelInfo.ModelName);

An important part to note here is that I'm using the 'Short' name of the assembly as opposed to the 'full' name (including Version, Culture and PublicToken). However, MSDN clearly states:

'assemblyName' can be either of the following: The simple name of an assembly, without its path or file extension.

• For example, you would specify TypeExtensions for an assembly whose path and name are .inTypeExtensions.dll.

• The full name of a signed assembly, which consists of its simple name, version, culture, and public key token; for example, "TypeExtensions, Version=1.0.0.0, Culture=neutral, PublicKeyToken=181869f2f7435b51".

Specifically, I'm trying to create an instance of class 'Action' defined in the Assembly 'SquidReports.DataCollector.Plugin.BES'. I'm explicitly referencing this assembly as a using directive at the top of the exact same *.cs file where I'm trying to create the instance.

I've tried the following suggestions from previous questions/answers:

Clean out your solution, rebuild and try again This seems to work in some ASP.NET projects, but this is plain old console app.

Check the referenced assemblies in your config file Again, this is a simple console app that only uses the GAC and libraries in the different projects of the same solution

1. Make sure the assembly is in the correct working directory:

Here we are...

2. Make sure the assembly is the same version on-disk

Yup...

3. The final recommendation was to use fuslogvw.exe.

I Have no experience using the tool, but there is one thing that I did find odd. Upon running the debug session, both a long-named and short-named version of my assembly showed up:

I had a look at both logs.

The short-named version does seem to generate some warnings:

=== Pre-bind state information ===

LOG: DisplayName = SquidReports.DataCollector.Plugin.BES Partial) WRN: Partial binding information was supplied for an assembly:

WRN: Assembly Name: SquidReports.DataCollector.Plugin.BES | Domain ID: 1

WRN: A partial bind occurs when only part of the assembly display name is provided.

WRN: This might result in the binder loading an incorrect assembly.

WRN: It is recommended to provide a fully specified textual identity for the assembly,

WRN: that consists of the simple name, version, culture, and public key token.

WRN: See whitepaper http://go.microsoft.com/fwlink/?LinkId=109270 for more information and common solutions to this issue.

... but it ends with being loaded successfully, and it clearly mentions my assembly at the correct location:

LOG: Attempting download of new URL file:///C:/Source/C#/SquidReports/SquidReports.DataCollector/bin/x86/Debug/SquidReports.DataCollector.Plugin.BES.DLL.

The log for the long-named version contains no suspicious messages.

Any more ideas?

EDIT: Here is a minimal definition of the Action class. It's purely a model-class.

public class Action : ICollectible
{
    public Action()
    {
        // Empty constructor
    }

    public Action(int actionID, string siteID, string name)
    {
        this.ActionID = actionID;
        this.SiteID = siteID;
        this.Name = name;
    }

    public int ID           { get; set; }   // Identity ID assigned by DB
    [Key]
    public int ActionID     { get; set; }   // Identity ID assigned by API
    public string SiteID    { get; set; }
    public string Name      { get; set; }
}

ICollectible interface and [Key] attribute are part of yet another assembly. Not sure if that would have effect?

EDIT 2: As Erik points out below, obviously I have done the exact same checks on this OTHER assembly as well.

解决方案

As you have found out, the assembly is being loaded, it just can't find the type (Action). You have to specify the full name of the type, Namespace.Action for .NET to find it.

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