C#原码动态编译功能实现~

原文：http://ms.mblogger.cn/minbear/posts/2379.aspx

 

C#原码动态编译功能实现~

主要使用System.Reflection.Emit这个namespace下的AssemblyBuilder，Code如下：

[C#]

using System;
using System.Text;
using System.Threading;
using System.Reflection;
using System.Reflection.Emit;

// The Point class is the class we will reflect on and copy into our
// dynamic assembly. The public static function PointMain() will be used
// as our entry point.
//
// We are constructing the type seen here dynamically, and will write it
// out into a .exe file for later execution from the command-line.
// ---
// class Point {
//   
//   private int x;
//   private int y;
//
//   public Point(int ix, int iy) {
//
//       this.x = ix;
//        this.y = iy;
//
//   }
//
//   public int DotProduct (Point p) {
//   
//       return ((this.x * p.x) + (this.y * p.y));
//
//   }
//
//   public static void PointMain() {
//     
//     Console.Write("Enter the 'x' value for point 1: ");
//     int x1 = Convert.ToInt32(Console.ReadLine());
//     
//     Console.Write("Enter the 'y' value for point 1: ");
//     int y1 = Convert.ToInt32(Console.ReadLine());
//
//     Console.Write("Enter the 'x' value for point 2: ");
//     int x2 = Convert.ToInt32(Console.ReadLine());
//     
//     Console.Write("Enter the 'y' value for point 2: ");
//     int y2 = Convert.ToInt32(Console.ReadLine());
//
//     Point p1 = new Point(x1, y1);
//     Point p2 = new Point(x2, y2);
//
//     Console.WriteLine("({0}, {1}) . ({2}, {3}) = {4}.",
//               x1, y1, x2, y2, p1.DotProduct(p2));
//   
//   }
//
// }
// ---

class AssemblyBuilderDemo {

   public static Type BuildDynAssembly() {

        Type pointType = null;

        AppDomain currentDom = Thread.GetDomain();

    Console.Write("Please enter a name for your new assembly: ");
    StringBuilder asmFileNameBldr = new StringBuilder();
        asmFileNameBldr.Append(Console.ReadLine());
    asmFileNameBldr.Append(".exe");
    string asmFileName = asmFileNameBldr.ToString();    

        AssemblyName myAsmName = new AssemblyName();
    myAsmName.Name = "MyDynamicAssembly";

        AssemblyBuilder myAsmBldr = currentDom.DefineDynamicAssembly(
                           myAsmName,
                           AssemblyBuilderAccess.RunAndSave);

        // We've created a dynamic assembly space - now, we need to create a module
        // within it to reflect the type Point into.

    ModuleBuilder myModuleBldr = myAsmBldr.DefineDynamicModule(asmFileName,
                                       asmFileName);
      
    TypeBuilder myTypeBldr =  myModuleBldr.DefineType("Point");
    
        FieldBuilder xField = myTypeBldr.DefineField("x", typeof(int),
                                                     FieldAttributes.Private);
        FieldBuilder yField = myTypeBldr.DefineField("y", typeof(int),
                                                     FieldAttributes.Private);

        // Build the constructor.

        Type objType = Type.GetType("System.Object");
        ConstructorInfo objCtor = objType.GetConstructor(new Type[0]);

        Type[] ctorParams = new Type[] {typeof(int), typeof(int)};
        ConstructorBuilder pointCtor = myTypeBldr.DefineConstructor(
                                   MethodAttributes.Public,
                                  CallingConventions.Standard,
                                  ctorParams);
        ILGenerator ctorIL = pointCtor.GetILGenerator();
        ctorIL.Emit(OpCodes.Ldarg_0);
        ctorIL.Emit(OpCodes.Call, objCtor);
        ctorIL.Emit(OpCodes.Ldarg_0);
        ctorIL.Emit(OpCodes.Ldarg_1);
        ctorIL.Emit(OpCodes.Stfld, xField);
        ctorIL.Emit(OpCodes.Ldarg_0);
        ctorIL.Emit(OpCodes.Ldarg_2);
        ctorIL.Emit(OpCodes.Stfld, yField);
        ctorIL.Emit(OpCodes.Ret);

    // Build the DotProduct method.

        Console.WriteLine("Constructor built.");

    MethodBuilder pointDPBldr = myTypeBldr.DefineMethod("DotProduct",
                                MethodAttributes.Public,
                                typeof(int),
                                new Type[] {myTypeBldr});
                               
    ILGenerator dpIL = pointDPBldr.GetILGenerator();
    dpIL.Emit(OpCodes.Ldarg_0);
    dpIL.Emit(OpCodes.Ldfld, xField);
    dpIL.Emit(OpCodes.Ldarg_1);
    dpIL.Emit(OpCodes.Ldfld, xField);
    dpIL.Emit(OpCodes.Mul_Ovf_Un);
    dpIL.Emit(OpCodes.Ldarg_0);
    dpIL.Emit(OpCodes.Ldfld, yField);
    dpIL.Emit(OpCodes.Ldarg_1);
    dpIL.Emit(OpCodes.Ldfld, yField);
    dpIL.Emit(OpCodes.Mul_Ovf_Un);
    dpIL.Emit(OpCodes.Add_Ovf_Un);
    dpIL.Emit(OpCodes.Ret);

      // Build the PointMain method.

        Console.WriteLine("DotProduct built.");

    MethodBuilder pointMainBldr = myTypeBldr.DefineMethod("PointMain",
                                MethodAttributes.Public |
                                MethodAttributes.Static,
                                typeof(void),
                                null);
        pointMainBldr.InitLocals = true;
    ILGenerator pmIL = pointMainBldr.GetILGenerator();

    // We have four methods that we wish to call, and must represent as
    // MethodInfo tokens:
    // - void Console.WriteLine(string)
    // - string Console.ReadLine()
    // - int Convert.Int32(string)
    // - void Console.WriteLine(string, object[])

    MethodInfo writeMI = typeof(Console).GetMethod(
                         "Write",
                         new Type[] {typeof(string)});
    MethodInfo readLineMI = typeof(Console).GetMethod(
                            "ReadLine",
                            new Type[0]);
    MethodInfo convertInt32MI = typeof(Convert).GetMethod(
                            "ToInt32",
                                new Type[] {typeof(string)});
    Type[] wlParams = new Type[] {typeof(string), typeof(object[])};
    MethodInfo writeLineMI = typeof(Console).GetMethod(
                         "WriteLine",
                         wlParams);

    // Although we could just refer to the local variables by
    // index (short ints for Ldloc/Stloc, bytes for LdLoc_S/Stloc_S),
    // this time, we'll use LocalBuilders for clarity and to
    // demonstrate their usage and syntax.

    LocalBuilder x1LB = pmIL.DeclareLocal(typeof(int));                
    LocalBuilder y1LB = pmIL.DeclareLocal(typeof(int));                
    LocalBuilder x2LB = pmIL.DeclareLocal(typeof(int));                
    LocalBuilder y2LB = pmIL.DeclareLocal(typeof(int));                
    LocalBuilder point1LB = pmIL.DeclareLocal(myTypeBldr);                
    LocalBuilder point2LB = pmIL.DeclareLocal(myTypeBldr);                
    LocalBuilder tempObjArrLB = pmIL.DeclareLocal(typeof(object[]));                

    pmIL.Emit(OpCodes.Ldstr, "Enter the 'x' value for point 1: ");    
    pmIL.EmitCall(OpCodes.Call, writeMI, null);
    pmIL.EmitCall(OpCodes.Call, readLineMI, null);
    pmIL.EmitCall(OpCodes.Call, convertInt32MI, null);
    pmIL.Emit(OpCodes.Stloc, x1LB);

    pmIL.Emit(OpCodes.Ldstr, "Enter the 'y' value for point 1: ");    
    pmIL.EmitCall(OpCodes.Call, writeMI, null);
    pmIL.EmitCall(OpCodes.Call, readLineMI, null);
    pmIL.EmitCall(OpCodes.Call, convertInt32MI, null);
    pmIL.Emit(OpCodes.Stloc, y1LB);

    pmIL.Emit(OpCodes.Ldstr, "Enter the 'x' value for point 2: ");    
    pmIL.EmitCall(OpCodes.Call, writeMI, null);
    pmIL.EmitCall(OpCodes.Call, readLineMI, null);
    pmIL.EmitCall(OpCodes.Call, convertInt32MI, null);
    pmIL.Emit(OpCodes.Stloc, x2LB);

    pmIL.Emit(OpCodes.Ldstr, "Enter the 'y' value for point 2: ");    
    pmIL.EmitCall(OpCodes.Call, writeMI, null);
    pmIL.EmitCall(OpCodes.Call, readLineMI, null);
    pmIL.EmitCall(OpCodes.Call, convertInt32MI, null);
    pmIL.Emit(OpCodes.Stloc, y2LB);

    pmIL.Emit(OpCodes.Ldloc, x1LB);
    pmIL.Emit(OpCodes.Ldloc, y1LB);
    pmIL.Emit(OpCodes.Newobj, pointCtor);
    pmIL.Emit(OpCodes.Stloc, point1LB);

    pmIL.Emit(OpCodes.Ldloc, x2LB);
    pmIL.Emit(OpCodes.Ldloc, y2LB);
    pmIL.Emit(OpCodes.Newobj, pointCtor);
    pmIL.Emit(OpCodes.Stloc, point2LB);

    pmIL.Emit(OpCodes.Ldstr, "({0}, {1}) . ({2}, {3}) = {4}.");
    pmIL.Emit(OpCodes.Ldc_I4_5);
    pmIL.Emit(OpCodes.Newarr, typeof(Object));
    pmIL.Emit(OpCodes.Stloc, tempObjArrLB);

    pmIL.Emit(OpCodes.Ldloc, tempObjArrLB);
    pmIL.Emit(OpCodes.Ldc_I4_0);
    pmIL.Emit(OpCodes.Ldloc, x1LB);
    pmIL.Emit(OpCodes.Box, typeof(int));
    pmIL.Emit(OpCodes.Stelem_Ref);

    pmIL.Emit(OpCodes.Ldloc, tempObjArrLB);
    pmIL.Emit(OpCodes.Ldc_I4_1);
    pmIL.Emit(OpCodes.Ldloc, y1LB);
    pmIL.Emit(OpCodes.Box, typeof(int));
    pmIL.Emit(OpCodes.Stelem_Ref);

    pmIL.Emit(OpCodes.Ldloc, tempObjArrLB);
    pmIL.Emit(OpCodes.Ldc_I4_2);
    pmIL.Emit(OpCodes.Ldloc, x2LB);
    pmIL.Emit(OpCodes.Box, typeof(int));
    pmIL.Emit(OpCodes.Stelem_Ref);

    pmIL.Emit(OpCodes.Ldloc, tempObjArrLB);
    pmIL.Emit(OpCodes.Ldc_I4_3);
    pmIL.Emit(OpCodes.Ldloc, y2LB);
    pmIL.Emit(OpCodes.Box, typeof(int));
    pmIL.Emit(OpCodes.Stelem_Ref);

    pmIL.Emit(OpCodes.Ldloc, tempObjArrLB);
    pmIL.Emit(OpCodes.Ldc_I4_4);
    pmIL.Emit(OpCodes.Ldloc, point1LB);
    pmIL.Emit(OpCodes.Ldloc, point2LB);
    pmIL.EmitCall(OpCodes.Callvirt, pointDPBldr, null);

    pmIL.Emit(OpCodes.Box, typeof(int));
    pmIL.Emit(OpCodes.Stelem_Ref);
    pmIL.Emit(OpCodes.Ldloc, tempObjArrLB);
    pmIL.EmitCall(OpCodes.Call, writeLineMI, null);

    pmIL.Emit(OpCodes.Ret);

        Console.WriteLine("PointMain (entry point) built.");

        pointType = myTypeBldr.CreateType();

        Console.WriteLine("Type baked.");

    myAsmBldr.SetEntryPoint(pointMainBldr);

        myAsmBldr.Save(asmFileName);

        Console.WriteLine("Assembly saved as '{0}'.", asmFileName);
        Console.WriteLine("Type '{0}' at the prompt to run your new " +
                  "dynamically generated dot product calculator.",
               asmFileName);

    // After execution, this program will have generated and written to disk,
        // in the directory you executed it from, a program named
    // .exe. You can run it by typing
    // the name you gave it during execution, in the same directory where
    // you executed this program.

    return pointType;
   
   }

   public static void Main() {

     Type myType = BuildDynAssembly();
     Console.WriteLine("---");

     // Let's invoke the type 'Point' created in our dynamic assembly.
   
     object ptInstance = Activator.CreateInstance(myType, new object[] {0,0});
                          
     myType.InvokeMember("PointMain",
              BindingFlags.InvokeMethod,
              null,
              ptInstance,
              new object[0]);

            
   }
}