如何在Imported或Embed Resource DLL中声明类型

Question

I'm actually looking for solution merge all DLL and EXE into single file.

I have asked a question at here:

How to use an DLL load from Embed Resource?

and I received suggestion that I can link the DLL as embed resource, then write the embed DLL file into memory and use DLLImport to import the DLL.

I followed the instructions here:

http://weblogs.asp.net/ralfw/archive/2007/02/04/single-assembly-deployment-of-managed-and-unmanaged-code.aspx

and below is what I have done:

[DllImport("System.Data.SQLite.dll")]
public static SQLiteConnection sqLiteConnection1 = new SQLiteConnection();

public Form1()
{
    ResourceExtractor.ExtractResourceToFile("MyApp.System.Data.SQLite.dll", "System.Data.SQLite.dll");
}

public static class ResourceExtractor
{
    public static void ExtractResourceToFile(string resourceName, string filename)
    {
        if (!System.IO.File.Exists(filename))
        using (System.IO.Stream s = System.Reflection.Assembly.GetExecutingAssembly().GetManifestResourceStream(resourceName))
        using (System.IO.FileStream fs = new System.IO.FileStream(filename, System.IO.FileMode.Create))
        {
            byte[] b = new byte[s.Length];
            s.Read(b, 0, b.Length);
            fs.Write(b, 0, b.Length);
        }
    }
}

but Visual Studio says that this block creates an error:

[DllImport("System.Data.SQLite.dll")]
public static SQLiteConnection sqLiteConnection1 = new SQLiteConnection();

Error 1 Attribute 'DllImport' is not valid on this declaration type. It is only valid on 'method' declarations.

How to declare the type inside that DLL?

Thanks you very much.

Answer 1

The DllImport attribute is used to declare methods from unmanaged DLLs.

Since System.Data.SQLite.dll is a managed assembly, what you need to do, after saving your assembly to disk, is to load it via Reflection , something like:

using System.Data;
...

var assembly = Assembly.LoadFile(@"path\to\System.Data.SQLite.dll");
var type = assembly.GetType("System.Data.SQLite.SQLiteConnection");
IDbConnection connection = (IDbConnection)Activator.CreateInstance(type);

Hope that helps.

Answer 2

If you want to stuff managed assemblies and the exe in one file, I suggest you look at ILMerge .

It is much easier to use than manually doing things with resources.

Answer 3

DllImport is only for native DLLs.

On embedding managed DLLs you have several options:

• use ILMerge (free)
  For howto see here and here

OR

• use some tool like SmartAssembly (commercial)
  it can embed and merge among other things (no need to change your source code)

OR

• code that yourself in less than 10 lines (free but minimal source code change)
  mark all needed dependencies as "embedded resource" - this way they are included in the EXE file... you need to setup an AssemblyResolve handler which at runtime reads from Resources and returns the needed DLLs to the .NET runtime...

On using a type from such an Assembly see these links (they including reference material AND some sample code etc.):

• http://msdn.microsoft.com/en-us/library/system.activator.createinstance.aspx
• https://stackoverflow.com/a/57450/847363
• http://msdn.microsoft.com/en-us/library/h538bck7.aspx (loads an ssembly from a byte array so there is no need to write that assembly to the filesystem)
• http://msdn.microsoft.com/en-us/library/system.reflection.assembly.gettype.aspx
• http://www.codeproject.com/Articles/32828/Using-Reflection-to-load-unreferenced-assemblies-a