【IT168 技术开发】

    最近在研究一个可配置系统的框架，在代码中大量使用了反射的方法，虽然借鉴到其他的语言，如java中反射性能都比较差，但是想到c#既然是一种强类型的语言，对于AppDomain中的类的调用应该性能不会差很多。

    今天在mvp站点上看到有人说反射的性能很差，要避免使用，就写了一个简单的例子测试了一下

namespace ReflectionTest.Test
{
public class CTester
{
public CTester()
{
a = 10;
}
public void test1()
{
a = (a - 0.0001) * 1.0001;
}
private double a;
public double geta() { return a; }
}
} 

    首先我们对于对象的构造进行测试，测试代码如下

private void test1()
{
label1.Text = "";
label3.Text = "";
DateTime now = DateTime.Now;
for (int i = 0; i < 1000; i++)
{
for (int j = 0; j < 100; j++)
{
CTester aTest = new CTester();
}
}
TimeSpan spand = DateTime.Now - now;
label1.Text = "time past " + spand.ToString();
}
private void test2()
{
label2.Text = "";
label4.Text = "";
DateTime now = DateTime.Now;
for (int i = 0; i < 1000; i++)
{
for (int j = 0; j < 100; j++)
{
Type theTest = Type.GetType("ReflectionTest.Test.CTester");
object theobj = theTest.InvokeMember(null, BindingFlags.CreateInstance
, null, null, null);
}
}
TimeSpan spand = DateTime.Now - now;
label2.Text = "time past " + spand.ToString();
} 

    测试结果直接调用的时间为16ms左右，而反射调用的则始终维持在5s 520ms左右，直接效率比较接近350倍。对于这个测试，很有趣的一点是：
    如果将test2中的Type theTest = Type.GetType("ReflectionTest.Test.CTester");

    移到循环之外，则相应的运行时间下降为1s 332 ms , 效率相差为20倍左右。

    接下来我们对成员函数调用进行了测试： 

      test1

private void button1_Click(object sender, EventArgs e)
...{
DateTime now = DateTime.Now;
CTester aTest = new CTester();
for (int i = 0; i < 1000; i++)
...{
for (int j = 0; j < 100; j++)
...{
aTest.test1();
}
}
TimeSpan spand = DateTime.Now - now;
label1.Text = "time past " + spand.ToString();
label3.Text = "value is now " + aTest.geta();
} 

    test2

private void button2_Click(object sender, EventArgs e)
{
DateTime now = DateTime.Now;
Type theTest = Type.GetType("ReflectionTest.Test.CTester");
object theobj = theTest.InvokeMember(null, BindingFlags.CreateInstance
, null, null, null);
for (int i = 0; i < 1000; i++)
{
for (int j = 0; j < 100; j++)
{
theTest.InvokeMember("test1", BindingFlags.InvokeMethod, null, theobj, new object[0]);
}
}
CTester thewar = theobj as CTester;
TimeSpan spand = DateTime.Now - now;
label2.Text = "time past " + spand.ToString();
label4.Text = "value is now " + thewar.geta();
} 

callvirt instance object [mscorlib]System.Type::InvokeMember(string,
valuetype [mscorlib]System.Reflection.BindingFlags,
class [mscorlib]System.Reflection.Binder,
object,
object[])