[英]Type casting in c# using the string name of the object type
I have the following code, should be easy to follow through 我有以下代码,应该很容易理解
public class Foo
{
public void FooHasAMethod()
{
Console.WriteLine("it is me, foo!!!");
}
}
public class Bar
{
public Foo FooProperty { get; set; }
}
public class FooBar
{
public static void Main()
{
Bar bar = new Bar{ FooProperty = new Foo() };
CallPropertyByName(bar, "Foo");
}
public static void CallPropertyByName(Bar bar, string propertyName)
{
PropertyInfo pi = bar.GetType().GetProperty(propertyName + "Property");
object fooObj = pi.GetValue(bar, null);
((Foo)fooObj).FooHasAMethod(); // this works
/* but I want to use
* ((Type.GetType(propertyName))fooObj).FooHasAMethod(); This line needs fix
* which doesnt work
* Is there a way to type cast using a string name of a object?
* */
}
}
If you're using .NET 4, it's actually really easy =D 如果您使用的是.NET 4,则实际上非常简单= D
dynamic obj = bar;
obj.FooProperty.FooHasAMethod();
However, if you just want to cast the result to some other type, you can do that at runtime with the Convert.ChangeType method: 但是,如果您只想将结果转换为其他类型,则可以在运行时使用Convert.ChangeType方法执行此操作:
object someBoxedType = new Foo();
Bar myDesiredType = Convert.ChangeType(typeof(Bar), someBoxedType) as Bar;
Now, this one has a strong link to the actual types Foo and Bar. 现在,这与实际类型Foo和Bar有很强的联系。 However, you can genericize the method to get what you want:
但是,您可以泛化该方法以获得所需的内容:
public T GetObjectAs<T>(object source, T destinationType)
where T: class
{
return Convert.ChangeType(typeof(T), source) as T;
}
Then, you can invoke like so: 然后,您可以像这样调用:
Bar x = GetObjectAs(someBoxedType, new Bar());
SomeTypeYouWant x = GetObjectAs(someBoxedType, Activator.CreateInstance(typeof("SomeTypeYouWant")));
Using the activator, you can at runtime create any type you want. 使用激活器,您可以在运行时创建所需的任何类型。 And the generic method is tricked by inference into attempting a convert from your boxedType to the runtime type.
泛型方法被推论诱骗,试图将boxedType转换为运行时类型。
In addition, if you want to just call a method on some dynamic property value, then the best practice (imo), would be to simply cast it as some desired object. 另外,如果只想对某个动态属性值调用方法,则最佳实践(imo)将只是将其强制转换为某些所需对象。
ISomething propValue = obj.GetProperty("FooPropery").GetValue(obj, null) as ISomething;
if(propValue != null)
propValue.FooHasAMethod();
Type fooObjType = fooObj.GetType();
MethodInfo method = fooObjType.GetMethod("FooHasAMethod");
method.Invoke(fooObj, new object[0]);
There's no way to cast by using string. 无法通过使用字符串进行强制转换。 But you can use dynamic , or MethodInfo with invoke
但是您可以将dynamic或MethodInfo与invoke一起使用
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