我有一堆IEnumerable集合,确切的数量和类型经常更改(由于自动代码生成).
它看起来像这样：
public class MyCollections {
public System.Collections.Generic.IEnumerable<SomeType> SomeTypeCollection;
public System.Collections.Generic.IEnumerable<OtherType> OtherTypeCollection;
...
在运行时,我想确定每个Type和它的计数,而不必在每次代码生成后重写代码.所以我正在寻找使用反射的通用方法.我正在寻找的结果是这样的：
MyType: 23 OtherType: 42
我的问题是我无法想象如何正确调用Count方法.这是我到目前为止：
// Handle to the Count method of System.Linq.Enumerable
MethodInfo countMethodInfo = typeof(System.Linq.Enumerable).GetMethod("Count",new Type[] { typeof(IEnumerable<>) });
PropertyInfo[] properties = typeof(MyCollections).GetProperties();
foreach (PropertyInfo property in properties)
{
Type propertyType = property.PropertyType;
if (propertyType.IsGenericType)
{
Type genericType = propertyType.GetGenericTypeDefinition();
if (genericType == typeof(IEnumerable<>))
{
// access the collection property
object collection = property.GetValue(someInstanceOfMyCollections,null);
// access the type of the generic collection
Type genericArgument = propertyType.GetGenericArguments()[0];
// make a generic method call for System.Linq.Enumerable.Count<> for the type of this collection
MethodInfo localCountMethodInfo = countMethodInfo.MakeGenericMethod(genericArgument);
// invoke Count method (this fails)
object count = localCountMethodInfo.Invoke(collection,null);
System.Diagnostics.Debug.WriteLine("{0}: {1}",genericArgument.Name,count);
}
}
}
解决方法
如果你坚持不懈努力; p
变化：
>如何获取泛型方法的countMethodInfo
> Invoke的参数
代码(注意obj是我的MyCollections实例)：
MethodInfo countMethodInfo = typeof (System.Linq.Enumerable).GetMethods().Single(
method => method.Name == "Count" && method.IsStatic && method.GetParameters().Length == 1);
PropertyInfo[] properties = typeof(MyCollections).GetProperties();
foreach (PropertyInfo property in properties)
{
Type propertyType = property.PropertyType;
if (propertyType.IsGenericType)
{
Type genericType = propertyType.GetGenericTypeDefinition();
if (genericType == typeof(IEnumerable<>))
{
// access the collection property
object collection = property.GetValue(obj,null);
// access the type of the generic collection
Type genericArgument = propertyType.GetGenericArguments()[0];
// make a generic method call for System.Linq.Enumerable.Count<> for the type of this collection
MethodInfo localCountMethodInfo = countMethodInfo.MakeGenericMethod(genericArgument);
// invoke Count method (this fails)
object count = localCountMethodInfo.Invoke(null,new object[] {collection});
System.Diagnostics.Debug.WriteLine("{0}: {1}",count);
}
}
}
