[英]Reflection.Emit throws BadImageFormatException
我試圖在運行時生成一個新的類/對象。
在閱讀了如何使用PropertyBuilder創建私有財產之后 ,我設法實現了一切,一切都像我需要的。
但是,一旦我試圖實例化我的新對象,我就會收到BadImageFormatException
這似乎是一個類似的問題,但尚未解決是否有任何方法可以檢測System.Reflection.Emit?
這是我的代碼:
領域:
internal class Field {
public string FieldName;
public Type FieldType;
public string Value;
}
發電機碼:
var xx = new List<Field>(new[] { new Field { FieldName = "Name", FieldType = typeof(string), Value = "Hello World" },
new Field { FieldName = "Id", FieldType = typeof(int), Value = "1" } });
this.DoVodoo(xx);
魔術
private dynamic DoVodoo(IEnumerable<Field> fields) {
var aName = new AssemblyName("DynamicAssemblyExample");
var ab = AppDomain.CurrentDomain.DefineDynamicAssembly(aName, AssemblyBuilderAccess.RunAndSave);
var mb = ab.DefineDynamicModule(aName.Name, aName.Name + ".dll");
// Create class with all needed Properties
var tb = mb.DefineType("ParamRow", TypeAttributes.Public, typeof(object));
foreach (var field in fields) {
var pb = tb.DefineProperty(field.FieldName, PropertyAttributes.None, CallingConventions.HasThis, field.FieldType, null);
var getSetAttr = MethodAttributes.Public | MethodAttributes.SpecialName | MethodAttributes.HideBySig;
// Define the "get" accessor method for the Property.
var custNameGetPropMthdBldr = tb.DefineMethod($"get_{field.FieldName}", getSetAttr, typeof(string), Type.EmptyTypes);
var custNameGetIL = custNameGetPropMthdBldr.GetILGenerator();
custNameGetIL.Emit(OpCodes.Ldarg_0);
custNameGetIL.Emit(OpCodes.Ldfld, custNameGetPropMthdBldr);
custNameGetIL.Emit(OpCodes.Ret);
// Define the "set" accessor method for CustomerName.
var custNameSetPropMthdBldr = tb.DefineMethod($"set_{field.FieldName}", getSetAttr, null, new[] { typeof(string) });
var custNameSetIL = custNameSetPropMthdBldr.GetILGenerator();
custNameSetIL.Emit(OpCodes.Ldarg_0);
custNameSetIL.Emit(OpCodes.Ldarg_1);
//custNameSetIL.Emit(OpCodes.Stfld, custNameGetPropMthdBldr);
custNameSetIL.Emit(OpCodes.Stfld, custNameSetPropMthdBldr);
custNameSetIL.Emit(OpCodes.Ret);
// Last, we must map the two methods created above to our PropertyBuilder to
// their corresponding behaviors, "get" and "set" respectively.
pb.SetGetMethod(custNameGetPropMthdBldr);
pb.SetSetMethod(custNameSetPropMthdBldr);
}
var finalType = tb.CreateType();
var result = new List<object>();
foreach (var field in fields) {
var inst = ab.CreateInstance(finalType.Name);
finalType.GetProperty(field.FieldName, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic).SetValue(inst, field.Value); //<-- Here comes the trouble
result.Add(inst);
}
return result;}
感謝您提供有關如何實例化我新創建的Type ParamRow
。
獎勵問題:為什么會有BadImageFormatException
?
附加信息:
Reflection.Emit
。 重要的是您收到的異常的.Message
:
字段令牌超出范圍。
這表明您不了解要在ldfld
/ stfld
使用哪個字段-這是因為要向其傳遞方法令牌( custNameGetPropMthdBldr
/ custNameSetPropMthdBldr
)而不是字段令牌。
您需要定義和使用一個字段:
var fb = tb.DefineField("__" + field.FieldName, field.FieldType, FieldAttributes.Private);
// ...
custNameGetIL.Emit(OpCodes.Ldarg_0);
custNameGetIL.Emit(OpCodes.Ldfld, fb);
custNameGetIL.Emit(OpCodes.Ret);
// ...
custNameSetIL.Emit(OpCodes.Ldarg_0);
custNameSetIL.Emit(OpCodes.Ldarg_1);
custNameSetIL.Emit(OpCodes.Stfld, fb);
custNameSetIL.Emit(OpCodes.Ret);
還要注意,通過反射創建對象時,使用Type
比使用名稱更有效。 這工作正常:
var inst = Activator.CreateInstance(finalType);
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