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C# 反射

反射是一种能够在运行时动态创建对象、调用对象属性、成员、方法、属性等的特性。通俗的讲,通过反射不需要添加引用DLL,就可以动态的给类的属性赋值,动态的调用里面的方法。我们在VS中给控件的属性赋值就是通过反射来完成的,此外在调用web服务时也可以通过反射去动态的创建代理对象,而不需要添加web引用,还有在开发插件化(多个DLL)的应用程序时,反射是一种很重要的机制。

因此,反射提供了一种更加灵活的方式,让我们根据需要进行动态的编程。这里举几个简单的例子以供参考:

1、动态调用系统自带的类的静态方法

 MethodInfo methodInfo = typeof(string).GetMethod("Concat", System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Static, null, new Type[] { typeof(string), typeof(string) }, null);
 object result = methodInfo.Invoke(null, new string[] { "Hello ", "Reflection" });
 Console.WriteLine(result.ToString());

 

2、动态调用系统自带的类的实例方法

string str = "Hello World";
object result = typeof(string).InvokeMember("Contains", BindingFlags.InvokeMethod, null, str, new object[] { "World" });
Console.WriteLine(result.ToString());

 

3、动态调用类库项目中的静态方法

namespace 类库项目
{
    public class Calculator
    {
        public static double Add(double a, double b)
        {
            return a + b;
        }

        public static double Sub(double a, double b)
        {
            return a - b;
        }

        public static double Mutiply(double a, double b)
        {
            return a * b;
        }

        public static double Divide(double a, double b)
        {
            return a / b;
        }
    }
}

反射调用:

object obj = Assembly.LoadFrom(AppDomain.CurrentDomain.BaseDirectory + "类库项目.dll").CreateInstance("类库项目.Calculator");

object addResult = obj.GetType().InvokeMember("Add", BindingFlags.Public | BindingFlags.Static | BindingFlags.InvokeMethod, null, obj, new object[] { 1, 2 });
object subResult = obj.GetType().InvokeMember("Sub", BindingFlags.Public | BindingFlags.Static | BindingFlags.InvokeMethod, null, obj, new object[] { 1, 2 });
object mutiplyResult = obj.GetType().InvokeMember("Mutiply", BindingFlags.Public | BindingFlags.Static | BindingFlags.InvokeMethod, null, obj, new object[] { 1, 2 });
object divideResult = obj.GetType().InvokeMember("Divide", BindingFlags.Public | BindingFlags.Static | BindingFlags.InvokeMethod, null, obj, new object[] { 1, 2 });

Console.WriteLine("add:{0}\t sub:{1}\t mutiply:{2}\t divide:{3}",
        addResult.ToString(),
        subResult.ToString(),
        mutiplyResult.ToString(),
        divideResult.ToString());

 

4、动态调用类库项目中的实例方法

namespace 类库项目
{
    public class Test
    {
        private int x;
        private string y;

        /// <summary>
        /// 属性X
        /// </summary>
        public int X { get { return x; } set { x = value; } }

        /// <summary>
        /// 属性Y
        /// </summary>
        public string Y { get { return y; } set { y = value; } }

        /// <summary>
        /// 默认无参构造函数
        /// </summary>
        public Test()
        {

        }

        /// <summary>
        /// 带两个参数的构造函数
        /// </summary>
        /// <param name="x"></param>
        /// <param name="y"></param>
        public Test(int x, string y)
        {
            this.X = x;
            this.Y = y;
        }

        /// <summary>
        /// 方法的重载1(无参)
        /// </summary>
        /// <returns></returns>
        public string Show()
        {
            return string.Format("这是Test里的Show方法,参数x为{0},y为{1}", X, Y);
        }

        /// <summary>
        /// 方法的重载2(带两个参数)
        /// </summary>
        /// <param name="x"></param>
        /// <param name="y"></param>
        /// <returns></returns>
        public string Show(int x, string y)
        {
            return string.Format("这是Test里的Show方法,参数x为{0},y为{1}", x, y);
        }

        /// <summary>
        /// 重写ToString方法
        /// </summary>
        /// <returns></returns>
        public override string ToString()
        {
            return string.Format("x的值为{0},y的值为{1}", x, y);
        }
    }
}

反射调用:

object obj2 = Assembly.LoadFrom(AppDomain.CurrentDomain.BaseDirectory + "类库项目.dll").CreateInstance("类库项目.Test");

//获取构造函数
ConstructorInfo constructorInfo = obj2.GetType().GetConstructor(new Type[] { typeof(int), typeof(string) });
//通过构造函数创建类的实例
object constructor = constructorInfo.Invoke(new object[] { 1, "guwei4037" });

//调用实例的ToString方法
Console.WriteLine(constructor.ToString());

//获取带两个参数的Show方法对象
MethodInfo methodInfo1 = obj2.GetType().GetMethod("Show", BindingFlags.Public | BindingFlags.Instance, null, new Type[] { typeof(int), typeof(string) }, null);

//返回带两个参数的Show方法的返回值
Console.WriteLine(methodInfo1.Invoke(constructor, new object[] { 1, "guwei4037" }).ToString());

//获取无参的Show方法
MethodInfo methodInfo2 = obj2.GetType().GetMethod("Show", BindingFlags.Public | BindingFlags.Instance, null, System.Type.EmptyTypes, null);

//动态设置属性的值
PropertyInfo[] propertyInfos = obj2.GetType().GetProperties();
foreach (PropertyInfo propertyInfo in propertyInfos)
{
    if (propertyInfo.Name.Equals("X"))
        propertyInfo.SetValue(constructor, 2, null);

    if (propertyInfo.Name.Equals("Y"))
        propertyInfo.SetValue(constructor, "guwei4037_new", null);
}

//返回无参的Show方法的返回值
Console.WriteLine(methodInfo2.Invoke(constructor, null).ToString());

 

posted @ 2017-12-08 13:50  guwei4037  阅读(735)  评论(0编辑  收藏  举报