public class DBUtil {
    Connection conn = null;
    Statement stmt = null;
    PreparedStatement ps = null;
    ResultSet rs = null;
    String url = null;
    String user = null;
    String password = null;
    String sql = null;
    int number;
    public  void openDb() {
        try {
            Class.forName("com.mysql.jdbc.Driver"); //
        } catch (ClassNotFoundException e) {
            System.out.println("");
            e.printStackTrace();//
        }
        try {
            url = "jdbc:mysql://localhost:3306/db";    
            user = "root";
            password = "root";
            conn = DriverManager.getConnection(url, user, password);
        } catch (SQLException e) {
            System.out.println("驱动加载异常");
            e.printStackTrace();
        }
    }
    public ResultSet query(String sql){
        try {
            stmt = conn.createStatement();
            rs = stmt.executeQuery(sql);
        } catch (SQLException e) {
            System.out.println("sql查询语句异常");
            e.printStackTrace();
        }
        return rs;
    }
            
    public Boolean insert(String sql){
        boolean boo=false;
        try {
            stmt = conn.createStatement();
            stmt.executeUpdate(sql);// 执
            boo=true;
        } catch (SQLException e) {
            System.out.println("插入语句异常");
            e.printStackTrace();
        }
        return boo;
    }
public void closeDb() {
          
                try {
                    if (rs != null) {
                        rs.close();
                        rs = null;
                    }
                    if (stmt != null) {
                        stmt.close();
                        stmt = null;
                    }
                    if (conn != null) {
                        conn.close();
                        conn = null;
                    }
                } catch (Exception e) {
                    System.out.println("sql连接关闭异常");
                    e.printStackTrace();
                }
    }
}