namespace System.Reflection
//加载相关的dll程序集
public static Assembly Load(string assemblyString);
//获取类型。如果当string表示的目标类型不在当前程序集中，则运行时Type.GetType会返回null。解决 的办法是：首先加载目标程序集，然后再使用Assembly.GetType方法来获取类型。
public virtual Type GetType(string name);
Type.GetConstructor Method (System) | Microsoft Docs
//Gets a specific constructor of the current Type 获取当前类的构造函数， Type[] types 用来支持不同入参的构造函数
public ConstructorInfo GetConstructor(Type[] types);
从简单的案例开始
class Invoke{ public static void Main() { Type type = typeof(StringBuilder); Type[] argTypes = new Type[] { typeof(System.String), typeof(System.Int32) }; ConstructorInfo cInfo = type.GetConstructor(argTypes); object[] argVals = new object[] { "Some string", 30 }; // Create the object and cast it to StringBuilder. StringBuilder invoke = (StringBuilder)cInfo.Invoke(argVals); StringBuilder direct = new StringBuilder("Some string", 30); if (invoke.Equals(direct)) { Console.WriteLine("Expected"); } }}
接下来我们来看一个具体的案例
private static IVstaHelper GetVstaHelper()
{
Assembly helperAssembly;
string assemblyName = "Microsoft.SqlServer.IntegrationServices.VSTA.VSTA16, Version=15.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91";
try
{
//完成相关dll的load
helperAssembly = Assembly.Load(assemblyName);
}
catch (FileNotFoundException)
{
s_tc.TraceError("Cannot load assembly {0}", assemblyName); // do not localize
throw new FileNotFoundException(assemblyName);
}
string typeName = "Microsoft.SqlServer.IntegrationServices.VSTA.VstaHelper";
//在 VSTA16的程序集中获取到VstaHelper类型
Type helperType = helperAssembly.GetType(typeName);
if (helperType == null)
{
s_tc.TraceError("Cannot load type {0}", typeName); // do not localize
throw new Exception(Localized.FailedToCreateVSTAHelper);
}
//选择了VstaHelper参数为空的构造函数
ConstructorInfo cinfo = helperType.GetConstructor(new Type[] { });
if (cinfo == null)
{
s_tc.TraceError("Cannot get VstaHelper constructor info"); // do not localize
throw new Exception(Localized.FailedToCreateVSTAHelper);
}
//回调构造函数，生成IVstaHelper
IVstaHelper result = cinfo.Invoke(null) as IVstaHelper;
if (result == null)
{
s_tc.TraceError("Cannot instantiate VstaHelper object"); // do not localize
throw new Exception(Localized.FailedToCreateVSTAHelper);
}
return result;
}
还有一个类似的问题 我们的项目因为一些依赖的原因 必须在csproj引入Microsoft.SqlServer.WizardFramework 15.0 但是我们的项目下游需要一个16.0的传参 于是：
void copyFromVersion15toVersion16(WizardInputs importWizardInputs ) {
string assemblyName = "Microsoft.SqlServer.WizardFramework, Version=16.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91";
Assembly assembly = Assembly.Load(assemblyName);
string typeName = "Microsoft.SqlServer.Management.UI.WizardInputs";
Type dType = assembly.GetType(typeName);
ConstructorInfo cinfo = dType.GetConstructor(new Type[] { });
importWizardInputstemp = cinfo.Invoke(null);
Type sType = typeof(WizardInputs);
foreach (PropertyInfo now in sType.GetProperties()) {
var name = dType.GetProperty(now.Name); if (name == null) continue; dType.GetProperty(now.Name).SetValue(importWizardInputstemp, now.GetValue(importWizardInputs));
}
}
