C#去掉字符串兩端空格以及去掉字符串中多余空格保留一個空格

string str = " asdf asd saddf sdfwrqeqw a asdf ";
string[] strs = str.Trim().Split(new char[]{' '},StringSplitOptions.RemoveEmptyEntries);
string finallStr = string.Join(" ",strs);