` // dbhelp help类，封装数据库基本信息以及关闭资源的方法

class DbHelp{
    //数据库连接信息
    public static String url = "jdbc:mysql://localhost:3306/blog";
    public static String user = "root";
    public static String password = "root";
    public static String driver = "com.mysql.jdbc.Driver";

    public static PreparedStatement ps = null;

    public static Connection conn = null;

    public ResultSet rs = null;

    //获取数据库连接的方法
    public static void getConnection(){
    try {
            Class.forName(driver);
            conn = DriverManager.getConnection(url, user, password);
            } catch (ClassNotFoundException e) {
                    e.printStackTrace();
            } catch (SQLException e) {
                    e.printStackTrace();
            }
    }

    // 关闭资源
    public void close(){
      try {
                ps.close();
                conn.close();
                rs.close();
            } catch (SQLException e) {
                    e.printStackTrace();
            }
        }
    }

// User实体类
public class User{
private int id;
private String name;
private  String contact;
private String telephone;
private String email;
private String remark;
private String userName;
private String address;


@Override
public String toString() {
return "User [id=" + id + ", name=" + name + ", contact=" + contact
+ ", telephone=" + telephone + ", email=" + email + ", remark="
+ remark + ", userName=" + userName + ", address=" + address+ "]";
}
    // get/set 方法
    。。。。。。
}    



 //数据库操作类
public class UserDemo extends DbHelp{

    public User getUser(){
        getConnection();
        User user = new User();
        String sql = "select * from t_sys_user where user_id = ?";
        try{
            ps = conn.prepareStatement(sql);
            // 设置参数，第一个问号的值为 8
            ps.setInt(1,8)
            rs = ps.executeQuery();
            while(rs.next()){
                user.setId(rs.getInt("id"));
                user.setName(rs.getString("name"));
                user.setContact(rs.getString("contact"));
                user.setEmail(rs.getString("email"));
                user.setRemark(rs.getString("remark"));
                user.setTelephone(rs.getString("telephone"));
            }
            }catch(SQLException e){
                e.printStackTrace();
        } 
            //关闭资源
            close();
            return user;
        }
    }

  //测试方法
public static void main(String[] a){
        UserDemo demo = new UserDemo();
        User user = demo.get();
        System.out.println(user.toString());
}

`