public class ConnDB {
    public Connection conn = null; 
    public Statement stmt = null; 
    public ResultSet rs = null; 
    private static String propFileName = "/connDB.properties"; // 指定资源文件保存的位置
    private static Properties prop = new Properties(); // 创建并实例化Properties对象的实例
    private static String dbClassName = "";//定义保存数据库驱动的变量
    private static String dbUrl = "";
    private static String dbUser = "";
    private static String dbPwd = "";
    
    //定义构造方法
    public ConnDB() {    
        try {            
            //将Properties文件读取到InputStream对象中
            InputStream in = getClass().getResourceAsStream(propFileName);
            prop.load(in); // 通过输入流对象加载Properties文件
            dbClassName = prop.getProperty("DB_CLASS_NAME",dbClassName); // 获取数据库驱动
            dbUrl = prop.getProperty("DB_URL", dbUrl);        //获取URL
            dbUser = prop.getProperty("DB_USER", dbUser);    //获取登录用户
            dbPwd = prop.getProperty("DB_PWD", dbPwd);        //获取密码
            
        } catch (Exception e) {
            e.printStackTrace(); 
        }
    }

    public Connection getConnection() {
        System.out.println("前conn="+conn);
        try {
            System.out.println("1111111");
            Class.forName(dbClassName);
            conn = DriverManager.getConnection(dbUrl, dbUser, dbPwd);
            System.out.println("数据库连接成功！"+dbUrl);
            
        } catch (Exception ee) {
            ee.printStackTrace();
        }
        System.out.println("后conn="+conn);
        if (conn == null) {
            System.err.println("警告: DbConnectionManager.getConnection() 获得数据库链接失败.\r\n\r\n链接类型:"
                            + dbClassName
                            + "\r\n链接位置:"
                            + dbUrl
                            + "\r\n用户"
                            + dbUser + "\r\n密码"+ dbPwd);
        }
        return conn;
    }