如何从自定义目录动态加载程序集，包括其依赖项？

Question

我发现以下代码可以从自定义位置动态加载 dll：

private void Form1_Load(object sender, EventArgs e)
{
    AppDomain currentDomain = AppDomain.CurrentDomain;
    currentDomain.AssemblyResolve += new ResolveEventHandler(MyResolveEventHandler);
}

private Assembly MyResolveEventHandler(object sender, ResolveEventArgs args)
{
    string folderPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
    string assemblyPath = Path.Combine(folderPath, "libs", new AssemblyName(args.Name).Name + ".dll");
    if (File.Exists(assemblyPath) == false) return null;
    Assembly assembly = Assembly.LoadFrom(assemblyPath);
    return assembly;
}

private void button1_Click(object sender, EventArgs e)
{
    var zip = ZipFile.Read("test.zip");

    foreach (ZipEntry file in zip)
    {
        file.Extract(".", ExtractExistingFileAction.OverwriteSilently);
    }
}

在某些情况下，此解决方案有效，但我得到的是 ZipDotNet dll：

InnerException  {"File or assembly name \"Ionic.Zip, Version=1.9.1.8, Culture=neutral, PublicKeyToken=edbe51ad942a3f5c\" or one of its dependencies, was not found. Operation is not supported. (Exception from HRESULT: 0x80131515)":"Ionic.Zip, Version=1.9.1.8, Culture=neutral, PublicKeyToken=edbe51ad942a3f5c"}   System.Exception {System.IO.FileLoadException}

自从它通过if (File.Exists(assemblyPath) == false) return null; 我猜它是加载Ionic.Zip.dll 的依赖项的问题？我也将如何解决它们？

Answer 1

查看Iconic.Zip.dllhere的源码，看到项目中唯一的引用是System、System.Data、System.Security、System.Xml，所以我怀疑是什么原因您无法加载它的任何引用。

我认为您的程序集解析方法有点过于简单。假设程序集名称与文件名相同，但情况并非总是如此。因此，您可以做的是为目标文件夹中的每个 dll 获取AssemblyName，并存储名称到文件的映射。然后，当解析器请求一个名称时，您在已知名称中查找它并加载程序集文件。这是该想法的快速实现。

private Dictionary<string, string> assemblyNameToFileMapping = new Dictionary<string, string>();

private void Form1_Load(object sender, EventArgs e)
{
    GetAssemblyNames();
    AppDomain currentDomain = AppDomain.CurrentDomain;
    currentDomain.AssemblyResolve += new ResolveEventHandler(MyResolveEventHandler);
}

private void GetAssemblyNames()
{
  string folderPath = Path.Combine(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location), "libs");
  foreach(string file in Directory.EnumerateFiles(folderPath, "*.dll"))
  {
     try
     {
         AssemblyName name = AssemblyName.GetAssemblyName(file);
         assemblyNameToFileMapping.Add(name.FullName, file);
     }
     catch { } // Just move on if we can't get the name.
  }
}

private Assembly MyResolveEventHandler(object sender, ResolveEventArgs args)
{
    string file;
    if (assemblyNameToFileMapping.TryGetValue(args.Name, out file))
    {
       return Assembly.LoadFrom(file);
    }
    return null;
}