实现网址的自动识别

public static string Auto(string str)
//========================//
// www.
// http://
// ftp://
// xx@xx.xx
// mms://
//========================//
{
Reg = new Regex("([^//]=>])(http://[A-Za-z0-9//./=//?%//-&_~`@':+!]+)");
str = Reg.Replace(str,"$1<a href=/"$2/" target=/"_blank/">$2</a>");
Reg = new Regex("^(http://[A-Za-z0-9//./=//?%//-&_~`@':+!]+)");
str = Reg.Replace(str,"<a href=/"$1/" target=/"_blank/">$1</a>");
Reg = new Regex("(http://[A-Za-z0-9//./=//?%//-&_~`@':+!]+)$");
str = Reg.Replace(str,"<a href=/"$1/" target=/"_blank/">$1</a>");
Reg = new Regex("([^//]=>])(ftp://[A-Za-z0-9//./=//?%//-&_~`@':+!]+)");
str = Reg.Replace(str,"$1<a href=/"$2/" target=/"_blank/">$2</a>");
Reg = new Regex("^(ftp://[A-Za-z0-9//./=//?%//-&_~`@':+!]+)");
str = Reg.Replace(str,"<a href=/"$1/" target=/"_blank/">$1</a>");
Reg = new Regex("(ftp://[A-Za-z0-9//./=//?%//-&_~`@':+!]+)$");
str = Reg.Replace(str,"<a href=/"$1/" target=/"_blank/">$1</a>");
Reg = new Regex("([^//]=>])(mms://[A-Za-z0-9//./=//?%//-&_~`@':+!]+)");
str = Reg.Replace(str,"$1<a href=/"$2/" target=/"_blank/">$2</a>");
Reg = new Regex("^(mms://[A-Za-z0-9//./=//?%//-&_~`@':+!]+)");
str = Reg.Replace(str,"<a href=/"$1/" target=/"_blank/">$1</a>");
Reg = new Regex("(mms://[A-Za-z0-9//./=//?%//-&_~`@':+!]+)$");
str = Reg.Replace(str,"<a href=/"$1/" target=/"_blank/">$1</a>");
Reg = new Regex("([a-z0-9_A-Z//-//.]{1,20})@([a-z0-9_//-]{1,15})//.([a-z]{2,4})");
str = Reg.Replace(str,"<a href=/"mailto:$1@$2.$3/" target=/"_blank/">$1@$2.$3</a>");
Reg = new Regex("([^/])(www.[A-Za-z0-9//./=//?%//-&_~`@':+!]+)");
str = Reg.Replace(str,"$1<a href=/"http://$2/" target=/"_blank/">$2</a>");
Reg = new Regex("^(www.[A-Za-z0-9//./=//?%//-&_~`@':+!]+)");
str = Reg.Replace(str,"<a href=/"http://$1/" target=/"_blank/">$1</a>");
Reg = new Regex("(www.[A-Za-z0-9//./=//?%//-&_~`@':+!]+)$");
str = Reg.Replace(str,"<a href=/"http://$1/" target=/"_blank/">$1</a>");
return str;
}