C#泛型和反射实例解析

public T abc<T>(T word)
{
return word;
return default(T); //关键字default可以对引用类型返回nullAble,int类型返回0,初始化一个T的感觉啦
}

abc<string>("x");

//struct 是 值类型 
//好处调用的是如果参数是值类型可以不用著名 test(100) 而不需要 test<int>(100);
public void test<T>(T number) where T : struct
{
int z = Convert.ToInt32(number);
//调用 test(100);
}
//下面的不知道好处在哪用在什么地方,
public void test2<T>(T lei) where T : class
{
} 
public void test3<T>() where T : stooges
{
} 
public T test4<T>() where T : new()
{
T abc = new T();
return abc;
}
public class stooges
{   
}

for(var attr in object) { object[attr]=value, attr = attr } 
var obj = new abc();
Type T = typeof(abc); //typeof(Class) 而不是 typeof(object) 哦
Type V = obj.GetType(); //obj.GetType() 就是typeof(object的class)
PropertyInfo[] attrs = obj.GetType().GetProperties(BindingFlags.Instance | BindingFlags.Public); //获取attrs
foreach (PropertyInfo attr in attrs) 
{
string key = attr.Name; //获取attr name
object value = attr.GetValue(obj, null); //获取value  
Type type = attr.PropertyType; //类型    
}

T.GetProperty("key").GetValue(obj, null); //read a key value
T.GetProperty("key").SetValue(obj, "", null); //write a value to key
//注意如果是字典 
T.GetProperty("Item").GetValue(obj, new [] {"id"}); //先拿Item 然后才通过 new[] {这里放指定的key}

class MyClass
{
public int x { get; set; }
public int y { get; set; }
public MyClass(int i)
{
  x = y + i;
}
public MyClass(int i, int j)
{
  x = i;
  y = j;
}
public int sum()
{
  return x + y;
}
}

Type t = typeof(MyClass);     
ConstructorInfo[] constructors = t.GetConstructors(); //使用这个方法获取构造函数列表    
for (int i = 0; i < constructors.Length; i++)
{
ConstructorInfo constructor = constructors[i];
//构造函数也是方法所以有 GetParameters
ParameterInfo[] parameters = constructor.GetParameters(); //获取当前构造函数的参数列表
string paraTypeName = parameters[0].ParameterType.Name; //方法的参数类型名称
string paraName = parameters[0].Name;// 方法的参数名         
}     
//调用构造函数
object[] args = new object[2];
args[0] = 10;
args[1] = 20;
//不用new 直接实例化
object instance = constructors[0].Invoke(args); //实例化一个这个构造函数有两个参数的类型对象,如果参数为空，则为null
object instance = (t)Activator.CreateInstance(t); 还有这种实例的方法,不清楚可以放参数没有

MethodInfo[] methods = T.GetMethods(BindingFlags.Public | BindingFlags.DeclaredOnly | BindingFlags.Instance);
foreach (MethodInfo method in methods)
{
string return_name = method.ReturnType.Name; //返回方法的返回类型
string name = method.Name;
if (name.Equals("sum", StringComparison.Ordinal)) //指定方法名调用
{
  int value = (int)method.Invoke(instance, null); //instance是之前实例好的对象,方法就是在这个对象之中
}
}

Type t = typeof(MyClass);
Console.WriteLine("----------------Method------------------");
MethodInfo[] methods = t.GetMethods();
foreach (MethodInfo method in methods)
{
  Console.WriteLine("Method:" + method);
  //Console.WriteLine(method); 
  //Console.WriteLine("返回值：" + method.ReturnParameter); 
}
Console.WriteLine("---------------Field-------------------"); //字段 ,比如这种 private static string name; 
FieldInfo[] fields = t.GetFields(BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.Static);
foreach (FieldInfo field in fields)
{
  Console.WriteLine("Field:" + field);
}
Console.WriteLine("--------------Member--------------------"); //成员即方法和属性
MemberInfo[] members = t.GetMembers();
foreach (MemberInfo member in members)
{
  Console.WriteLine("Member:" + member);
}
Console.WriteLine("--------------Property--------------------"); //属性
PropertyInfo[] properties = t.GetProperties();
foreach (PropertyInfo property in properties)
{
  Console.WriteLine("Property:" + property);
}
Console.WriteLine("--------------Constructor--------------------"); //构造函数
ConstructorInfo[] constructors = t.GetConstructors(BindingFlags.NonPublic | BindingFlags.Instance);
foreach (ConstructorInfo constructor in constructors)
{
  Console.WriteLine("Constructor:" + constructor);
}