c# - 无法转换类型为 'System.Reflection.RuntimePropertyInfo' 的对象

Question

我有库和控制台程序。程序动态加载库。库中存在字节数组。我试着得到这个数组。在程序中:

MemberInfo[] ByteArrayFile = HtmlPackage.GetMember("HtmlFile");
FieldInfo field;
try
{
   field = (FieldInfo)ByteArrayFile[0];//throw exception here
}
catch (Exception e)
{
  String err = e.ToString();
  throw e;
}
byte[] HtmlFileArray = (byte[])field.GetValue(htmlPackage);

此错误抛出异常:

"System.InvalidCastException: Unable to cast object of type 'System.Reflection.RuntimePropertyInfo' to type 'System.Reflection.FieldInfo'.\r\n at ...

那么它是如何修复的呢？

Answer 1

字段 (FieldInfo) 和属性 (PropertyInfo) 不共享 API - 因此您需要解决它:

MemberInfo member = ByteArrayFile[0];
byte[] HtmlFileArray;
switch (member.MemberType)
{
    case MemberTypes.Field:
        HtmlFileArray = (byte[])(((FieldInfo)member).GetValue(htmlPackage));
        break;
    case MemberTypes.Property:
        HtmlFileArray = (byte[])(((PropertyInfo)member).GetValue(htmlPackage));
        break;
    default:
        throw new NotSupportedException(member.MemberType.ToString());
}

但是，这要容易得多(也更有效(由于策略缓存)，而不会引入任何额外的弱点):

byte[] HtmlFileArray = ((dynamic)htmlPackage).HtmlFile;