java连sql server 菜鸟问题

import java.sql.*;

public class TestDB {
    public static void main(String[] args) {
        String driverName = "com.microsoft.jdbc.sqlserver.SQLServerDriver";
        String dbURL = "jdbc:microsoft:sqlserver://localhost:1433; DatabaseName=pubs";
        String userName = "sa";
        String userPwd = "";
        Connection dbConn;

        try {
            Class.forName("com.microsoft.jdbc.sqlserver.SQLServerDriver");
            dbConn = DriverManager.getConnection(dbURL, userName, userPwd);
            System.out.println("Connection Successful!");
        } catch (Exception e) {
            e.printStackTrace();

        }
    }
}
如何才能连上呢？？？
运行结果：
java.lang.ClassNotFoundException: com.microsoft.jdbc.sqlserver.SQLServerDriver
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClassInternal(Unknown Source)
    at java.lang.Class.forName0(Native Method)
----------------解决方案--------------------------------------------------------
没有加驱动把？？
----------------解决方案--------------------------------------------------------
确认你的驱动(*.jar)有没有
还有sp4补丁安装没
----------------解决方案--------------------------------------------------------