C#使用反射机制获取类信息
１．用反射动态创建类实例，并调用其公有成员函数。
//新建一个类库项目，增加一个GetSum方法。
using System;
namespace ClassLibrary1
{
public class Class1
{
public Class1()
{
}
public int GetSum(int x, int y)
{
return x + y;
}
}
}
//再另建一个项目，在项目中引用上面生成的ClassLibrary1.DLL
System.Reflection.Assembly a = System.Reflection.Assembly.LoadFrom("ClassLibrary1.DLL");
System.Type t = a.GetType("ClassLibrary1.Class1");
//动态生成ClassLibrary1.Class类的实例
Object theObj = System.Activator.CreateInstance(t);
//参数信息，GetSum需要两个int参数
System.Type[] paramTypes = new System.Type[2];
paramTypes[0] = System.Type.GetType("System.Int32");
paramTypes[1] = System.Type.GetType("System.Int32");
System.Reflection.MethodInfo mi = t.GetMethod("GetSum", paramTypes);
//参数值
Object[] parameters = new Object[2];
parameters[0] = 3;
parameters[1] = 4;
Object returnValue = mi.Invoke(theObj, parameters);
Console.WriteLine("ClassLibrary1.Class1.GetSum(3, 4) returns: {0}", returnValue.ToString());
2.用反射访问类的私有成员。
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的反射机制可以做到。
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;
// Fields
FieldInfo 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();
// Properties
PropertyInfo 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();
// Methods
MethodInfo 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 Field
Private Field
New Private Field
Protected Property
Private Property
New Private Property
Protected Method Invoked
Private Method Invoked
事件，一样可以操作， EventInfo :-)
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的反射机制可以做到。
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;
// Fields
FieldInfo 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();
// Properties
PropertyInfo 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();
// Methods
MethodInfo 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 Field
Private Field
New Private Field
Protected Property
Private Property
New Private Property
Protected Method Invoked
Private Method Invoked
事件，一样可以操作， EventInfo :-)
原地址：http://blog.csdn.net/zhoufoxcn/article/details/1358095
