No suitable driver found for jbdc:sqlserver

1.我的连接URL格式是：ct=DriverManager.getConnection("jbdc:sqlserver://localhost:1433;DatabaseName=mytest","sa","supersun");
2.驱动字符是：Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
3Sqljdbc42.jar包已经加入C:\Program Files\Java\jre1.8.1\lib\ext文件夹下了；

为什么还是显示没有合适的驱动呢，小白求救

http://blog.csdn.net/jiefodeheshang/article/details/14522081