MEF合成错误，导出不能正常工作

本文关键字：常工作 工作 不能 错误 MEF | 更新日期: 2023-09-27 18:01:30

这是我的表单，它应该显示从我导入的类的结果:

public partial class Form1 : Form
{
    [Import(typeof(ITests))]
    public ITests Template;
    public string texter;
    public Form1()
    {
        InitializeComponent();
        texter = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments) + "''bin''dll";
        textBox1.Text = texter;
        string[] array = Directory.GetFiles(texter, "*.dll");
        foreach(string file in array)
        {
            textBox1.Text += Environment.NewLine + file;
        }
        Program();
    }
    public void Program()
    {
        AggregateCatalog catalog = new AggregateCatalog();
        catalog.Catalogs.Add(new DirectoryCatalog(texter));
        Console.WriteLine(catalog.Catalogs);
        try
        {
            CompositionContainer container = new CompositionContainer(catalog);
            container.ComposeParts(this);
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }
    }
}

这是我的公共接口:我已经在两个项目中导入了它们，所以我已经尝试避免汇编引用错误

namespace ClassLibrary1
{
    public interface ITests
    {
        string Result(string result);
    }
}

这是我的DLL与导出代码:

namespace WindowsFormsApplication1
{
    public class Template 
    {
        //Please write all your tests in this class
        //[TestClass]
        public class Tests
        {
            //example of class
            //[TestMethod]
            public class Example : ITests
            {
                [Export(typeof(ITests))]
                public string Result(string res)
                {
                    string resa = res + " dit is door de test gegaan";
                    return resa;
                }
            }
            //[TestMethod]
            public class ExampleTest2
            {
            }
        }
    }
}

我得到这个错误:

类型的第一次机会异常"System.ComponentModel.Composition.Primitives.ComposablePartException"发生在System.ComponentModel.Composition.dll中'WindowsFormsApplication1.vshost.exe' (Managed (v4.0.30319)): Loaded

" C: ' Windows '会议' GAC_MSIL ' Microsoft.VisualStudio.DebuggerVisualizers ' 11.0.0.0__b03f5f7f11d50a3a ' Microsoft.VisualStudio.DebuggerVisualizers.dll"这篇作文产生了一个写作错误。根本原因是下面提供。检查CompositionException。的Errors属性更详细的信息

1)导出"WindowsFormsApplication1.Template+Tests+Example"。结果(ContractName="ClassLibrary1.ITests")'不能赋值给类型'ClassLibrary1.ITests'.

导致:无法设置导入"WindowsFormsApplication1.Form1.Template(ContractName=" classlibrary . itests ")'"WindowsFormsApplication1.Form1"。元素:WindowsFormsApplication1.Form1.Template(ContractName = " ClassLibrary1.ITests")——>WindowsFormsApplication1。Form1

MEF合成错误，导出不能正常工作

看起来你把[Export]放在了错误的地方。您正在尝试导出Result，这是一个字符串类型ittests。相反，导出应该位于您的类级别:

[Export(typeof(ITests))]
public class Example : ITests
{
    public string Result(string res)
    {
        string resa = res + " dit is door de test gegaan";
        return resa;
    }
}
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