C # Implementation dynamically invokes Windows DLL

Call Method:

Object obj = Windllinvoke ("Kernel32.dll", "Beep", new object[] {750, n, typeof (void));

Function code:

1 [System.Runtime.InteropServices.DllImport ("kernel32")]
2 private static extern IntPtr LoadLibrary (string lplibfilename);
3
4 [System.Runtime.InteropServices.DllImport ("kernel32")]
5 private static extern IntPtr GetProcAddress (IntPtr hmodule, string lpprocname);
6
7 [System.Runtime.InteropServices.DllImport ("kernel32")]
8 private static extern IntPtr FreeLibrary (IntPtr hlibmodule);
9
10///
11///Dynamic Call to Windows DLL
12///
///DLL filename
14///function name to be called
15///Function parameters
16///return value
17///Call Result
Private static Object Windllinvoke (String fileName, String funname, object[] objparams, Type returntype)
19 {
IntPtr libhandle = IntPtr.Zero;
21st
Try
23 {
24//Get function address
Libhandle = LoadLibrary (FileName);
if (Libhandle = = IntPtr.Zero) return null;
IntPtr procaddres = GetProcAddress (Libhandle, funname);
if (procaddres = = IntPtr.Zero) return null;
29
30//Get parameter type
type[] Paramtypes = new Type[objparams.length];
for (int i = 0; i < objparams.length; ++i)
33 {
Paramtypes[i] = objparams[i]. GetType ();
35}
36
37//Build Call Method model
AssemblyName asembyname = new AssemblyName ();
Asembyname.name = "windllinvoke_assembly";
AssemblyBuilder Asembybuilder = AppDomain.CurrentDomain.DefineDynamicAssembly (Asembyname, Assemblybuild Eraccess.run);
ModuleBuilder ModuleBuilder = Asembybuilder.definedynamicmodule ("Windllinvoke");
MethodBuilder MethodBuilder = Modulebuilder.defineglobalmethod ("Invokefun", Methodattributes.public | M Ethodattributes.static, ReturnType, paramtypes);
43
44//Get a ilgenerator for sending the required IL
ILGenerator IL = Methodbuilder.getilgenerator ();
for (int j = 0; j < paramtypes.length; ++j)
47 {
48//Press the parameters into the stack
if (Paramtypes[j]. Isvaluetype)
50 {
Wu IL. Emit (Opcodes.ldarg, J); by Value
52}
Or else
54 {
IL. Emit (Opcodes.ldarga, J); by addrsss
56}
57}
58
59//Determine processor type
if (intptr.size = 4)
61 {
The IL. Emit (OPCODES.LDC_I4, Procaddres.toint32 ());
63}
$ else if (Intptr.size = 8)
65 {
IL. Emit (Opcodes.ldc_i8, Procaddres.toint64 ());
67}
Or else
69 {
throw new PlatformNotSupportedException ("Sorry, I don't know you!") ");
71}
72
IL. Emitcalli (Opcodes.calli, Callingconvention.stdcall, ReturnType, paramtypes);
The IL. Emit (Opcodes.ret); return value
Modulebuilder.createglobalfunctions ();
76
77//Get method information
MethodInfo MethodInfo = Modulebuilder.getmethod ("Invokefun");
79
Methodinfo.invoke (null, objparams);//Call method and return its value
81}
The catch is {return null;}
and finally
84 {
if (libhandle!= IntPtr.Zero) FreeLibrary (Libhandle); Releasing resources
86}
87}