如果是C++,我们可以计算对象内成员的位置,然后偏移指针以访问类型的所有非公开成员。但是.NET对象完全受GC管理,地址根本无法得到,并且也无法通过指针调用方法。
当然... 这是一种很不值得推荐的技巧,访问非公有成员很可能破坏对象状态,造成不可预料的后果。但是无论如何,利用.NET的反射机制可以轻松做到这一点。
比如这样一个类:
class MyClass
{
private string PrivateField = "Private Field";
protected string ProtectedField = "Protected Field";
private string _ProtectedProperty = "Protected Property";
protected string ProtectedProperty
{
get{return _ProtectedProperty;}
set{_ProtectedProperty = value;}
}
private string _PrivateProperty = "Private Property";
private string PrivateProperty
{
get{return _PrivateProperty;}
set{_PrivateProperty = value;}
}
protected void ProtectedMethod()
{
Console.WriteLine("Protected Method Invoked");
}
private void PrivateMethod()
{
Console.WriteLine("Private Method Invoked");
}
}
除了默认的构造函数,没有任何成员是公开的,但是我仍然想获取和设置Field和Property的值,以及调用那两个方法。方法是:
MyClass mc = new MyClass();Type t = typeof(MyClass);BindingFlags bf = BindingFlags.Instance | BindingFlags.NonPublic;// FieldsFieldInfo fi_protected = t.GetField("ProtectedField",bf);FieldInfo fi_private = t.GetField("PrivateField",bf);Console.WriteLine(fi_protected.GetValue(mc));Console.WriteLine(fi_private.GetValue(mc));fi_private.SetValue(mc,"New Private Field");Console.WriteLine(fi_private.GetValue(mc));Console.WriteLine();// PropertiesPropertyInfo pi_protected = t.GetProperty("ProtectedProperty", bf);PropertyInfo pi_private = t.GetProperty("PrivateProperty", bf);Console.WriteLine(pi_protected.GetValue(mc,null));Console.WriteLine(pi_private.GetValue(mc,null));pi_private.SetValue(mc,"New Private Property",null);Console.WriteLine(pi_private.GetValue(mc,null));Console.WriteLine();// MethodsMethodInfo mi_protected = t.GetMethod("ProtectedMethod", bf);MethodInfo mi_private = t.GetMethod("PrivateMethod", bf);mi_protected.Invoke(mc,null);mi_private.Invoke(mc,null);Console.ReadLine();
输出:
Protected FieldPrivate FieldNew Private FieldProtected PropertyPrivate PropertyNew Private PropertyProtected Method InvokedPrivate Method Invoked
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