改成:
import java.sql.*;
import javax.naming.*;
import java.util.*;public class sqltomy
{

public static void main(String[] args) throws Exception //modified
{
     Class.forName("org.gjt.mm.mysql.Driver").newInstance();
      String url = "jdbc:mysql://localhost:3306/centerdb?user=root&password=&useUnicode=true&characterEncoding=gb2312" ;
Connection conn = DriverManager.getConnection(url);
Statement stmt=conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
String sql = "select * from aaa limit 0,10";
ResultSet rs=stmt.executeQuery(sql); 
while(rs.next())
{
System.out.println(rs.getString(0));
}
}
}