【IT168 评论】ToString方法大概是.Net时被用得最多的方法了，所有类型都，引用的，值的，都传承了这个从祖先Object开始的光荣传统。调用一次ToString，相当于惊堂木“啪”一下，大喝“堂下案犯报上名来”，这家伙就全招了。
可是写程序如查案，形形色色的人都有，对于些记性差，反应迟钝的家伙，就没那么顺利了。梅(枚)举人就是其中之一，来审问下看看：
static void testEnumToString()
{
var day = DayOfWeek.Wednesday;
string value = null;
for (int i = 0; i < 1000000; i++)
{
value = day.ToString();
}
Console.WriteLine(value);
}
{
var day = DayOfWeek.Wednesday;
string value = null;
for (int i = 0; i < 1000000; i++)
{
value = day.ToString();
}
Console.WriteLine(value);
}
整理下结果：
| 次数 | 1 | 2 | 3 | 4 |
| 时间(ms) | 7135 | 7009 | 7174 | 7010 |
看上去没什么，不过根据本府以往的断案经验，其中似有猫腻。本着勿枉勿纵，对人民负责的态度，不怕麻烦，另寻突破口：
static void testEnumToString2()
{
var day = DayOfWeek.Wednesday;
string value = null;
for (int i = 0; i < 1000000; i++)
{
switch (day)
{
case DayOfWeek.Friday:
value = "Friday";
break;
case DayOfWeek.Monday:
value = "Monday";
break;
case DayOfWeek.Saturday:
value = "Saturday";
break;
case DayOfWeek.Sunday:
value = "Sunday";
break;
case DayOfWeek.Thursday:
value = "Thursday";
break;
case DayOfWeek.Tuesday:
value = "Tuesday";
break;
case DayOfWeek.Wednesday:
value = "Wednesday";
break;
default:
break;
}
}
Console.WriteLine(value);
}
{
var day = DayOfWeek.Wednesday;
string value = null;
for (int i = 0; i < 1000000; i++)
{
switch (day)
{
case DayOfWeek.Friday:
value = "Friday";
break;
case DayOfWeek.Monday:
value = "Monday";
break;
case DayOfWeek.Saturday:
value = "Saturday";
break;
case DayOfWeek.Sunday:
value = "Sunday";
break;
case DayOfWeek.Thursday:
value = "Thursday";
break;
case DayOfWeek.Tuesday:
value = "Tuesday";
break;
case DayOfWeek.Wednesday:
value = "Wednesday";
break;
default:
break;
}
}
Console.WriteLine(value);
}
呈堂证供一上，满堂皆惊：
| 次数 | 1 | 2 | 3 | 4 |
| 时间(ms) | 2 | 1 | 1 | 1 |
我大怒，“大胆狂徒，还不从实招来，不然休怪本府大刑伺候”，梅举人哪见这阵势，浑身哆嗦，头拄地跪着，一会儿没了声息，衙役拖起一看，竟吓晕过去了。
“大人，是否冷水浇醒用刑”，我想，看案犯这德性，也挨不住几板子，说“先到案犯家里，搜查证据”。能干的捕头Reflector领命，一下子找到了线索：
public override string ToString()
{
return InternalFormat((RuntimeType) base.GetType(), this.GetValue());
}
private static string InternalFormat(RuntimeType eT, object value)
{
if (eT.IsDefined(typeof(FlagsAttribute), false))
{
return InternalFlagsFormat(eT, value);
}
string name = GetName(eT, value);
if (name == null)
{
return value.ToString();
}
return name;
}
{
return InternalFormat((RuntimeType) base.GetType(), this.GetValue());
}
private static string InternalFormat(RuntimeType eT, object value)
{
if (eT.IsDefined(typeof(FlagsAttribute), false))
{
return InternalFlagsFormat(eT, value);
}
string name = GetName(eT, value);
if (name == null)
{
return value.ToString();
}
return name;
}
果然不出所料，案犯肆无忌惮地用了反射，至此案件真相大体明了。如IsDefined和GetName两处，深究下去，触目惊心，令人发指。
可惜天下人，有多少还被蒙在鼓里，浑然不觉，荼毒流弊甚为深远。正本清源之路，漫漫修远。本府一已之力，深感力不从心，望和天下有志之士一道，扬善锄恶，共致太平盛世。
