[英]Use reflection to invoke method
在使用Azure ServiceFabric时,我们使用StateManager.GetStateAsync
方法来获取值,该方法可用于在类之类的对象类型中获取值。
我正在尝试下面的代码
var typeObj = Activator.CreateInstance(type);
var method = typeof(IActorStateManager).GetMethod(nameof(IActorStateManager.GetStateAsync));
var generic = method.MakeGenericMethod(type);
dynamic task = generic.Invoke(typeObj, new[] { stateName })
object result = await task;
通过这种方法,我得到了例外。
Data: {System.Collections.ListDictionaryInternal}
HResult: -2146232829
HelpLink: null
InnerException: null
Message: "Object does not match target type."
Source: "mscorlib"
StackTrace: "at System.Reflection.RuntimeMethodInfo.CheckConsistency(Object target)
at System.Reflection.RuntimeMethodInfo.InvokeArgumentsCheck(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)"
TargetSite: {Void CheckConsistency(System.Object)}
最有可能的是,这里有些事情被弄糊涂了。 如果您的代码就是您实际执行的代码,则说明您过度/滥用了type
变量。
让我们确定该type
为具体的ActorStateManager
。 然后
var typeObj = Activator.CreateInstance(type); // typeobj is now ActorStateManager
错误可能在这里:
var generic = method.MakeGenericMethod(type);
// generic is now StateManager.GetStateAsync<ActorStateManager>
您的意图不是创建StateManager.GetStateAsync<ActorStateManager>
,而是创建StateManager.GetStateAsync<ActorStateManager>
StateManager.GetStateAsync<bool>
或StateManager.GetStateAsync<DateTime>
。
另外,我的GetStateAsync 将(可选)cancellationToken作为第二个参数,最好在进行反射时明确显示。
所以我想这就是您想要做的:
public async Task<object> TryLotsOfTypesAndIgnoreErrors(string stateName)
{
var typeObj = Activator.CreateInstance(typeof(ActorStateManager));
foreach (var typeParam in new[] {typeof(bool), typeof(string)})
{
try
{
var method = typeof(IActorStateManager).GetMethod(nameof(IActorStateManager.GetStateAsync));
var generic = method.MakeGenericMethod(typeParam);
var task = (Task) generic.Invoke(typeObj, new object[] { stateName, CancellationToken.None });
await task;
return task.GetType().GetProperty(nameof(Task<object>.Result))?.GetValue(task);
}
catch
{
// TODO: Catch only exception specific to type mismatch
}
}
return null;
}
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