用JDBC连接MySQL的问题

我的mysql用commandline能用，我把mysql-connector-java-3.1.12-bin.jar放在C:\根目录底下，并在classpath里设置成“C:\mysql-connector-java-3.1.12-bin.jar”，为什么会发生一下错误呢？
“java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
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)
at java.lang.Class.forName(Unknown Source)
at jdbcExample.Jdbc11.main(Jdbc11.java:13)”
以下是代码：
package jdbcExample;
import java.sql.*;
public class Jdbc11 {

/**
* @param args
*/
public static void main(String[] args) {
try {
Statement stmt;
Class.forName("com.mysql.jdbc.Driver");
String url ="jdbc:mysql://localhost:3306/mysql";
Connection con =DriverManager.getConnection(url,"gogo", "123456");
System.out.println("URL: " + url);
System.out.println("Connection: " + con);
stmt = con.createStatement();
stmt.executeUpdate("CREATE DATABASE JunkDB");
stmt.executeUpdate(
"GRANT SELECT,INSERT,UPDATE,DELETE," +
"CREATE,DROP " +
"ON JunkDB.* TO 'auser'@'localhost' " +
"IDENTIFIED BY 'drowssap';");
con.close();
}catch( Exception e ) {
e.printStackTrace();
}//end catch
}//end main
}//end class Jdbc11