package ll.util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class DBCon {
      
       /**
       * 驱动程序
       */
       private static String driver="com.mysql.jdbc.Driver";
       /**
       * 连接数据库的URL
       */
       private static String url="jdbc:mysql://localhost:3306/onlineexam";
       /**
       * 用户名
       */
       private static String username="root";
       /**
       * 密码
       */
       private static String password="r00tb0x";
       //private static String password="123456";
       /**
       * 数据库连接对象
       */
       private static Connection con;
       /**
       * 获得数据库连接
       * @return 数据库连接,可能
       */
       public static Connection getCon() {
              try {
                     Class.forName(driver);
                     if (con == null || con.isClosed()) {
                            System.out.println("建立新的数据库连接");
                            con = DriverManager.getConnection(url, username, password);
                     }
              } catch (ClassNotFoundException e) {
                     System.out.println("驱动程序找不到,原因:"+ e.getMessage());