Java第三方jar包.数据库连接

1.用户登录

    /*
     * 用户登陆
     */
public class Login {
        public static void main(String[] args) {
            //接收用户输入的账号和密码
            Scanner scanner = new Scanner(System.in);
            System.out.println("请输入账号密码");
            String name = scanner.nextLine();
            System.out.println("请输入密码");
            String password = scanner.nextLine();
            //调用查询方法
            User findUser = DoLogin.findUser(name, password);
            if (findUser!=null) {
                System.out.println("登陆成功");
            }else {
                System.out.println("账号密码不匹配");
            }
            //sql语句的注入问题添加一个恒成立的条件
            //select *from users  where name  ='131313' 
      } 
}

2.创建User类,类中的变量与数据库中的字段名一一对应

public class User {
            //把对象保存到数组当中并遍历打印
            //对象中声明的属性名尽量和数据库中的字段名相同
    private int id;
    private String  password;
    private String name;
    private String email;
    private Date  birthday;

    public User() {
        super();
        // TODO Auto-generated constructor stub
    }

    public User(int id, String password, String name, String email, Date birthday) {
        super();
        this.id = id;
        this.password = password;
        this.name = name;
        this.email = email;
        this.birthday = birthday;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public Date getBrithday() {
        return birthday;
    }

    public void setBrithday(Date brithday) {
        this.birthday = brithday;
    }

    @Override
    public String toString() {
        return "User [id=" + id + ", password=" + password + ", name=" + name + ", email=" + email + ", birthday="
                + birthday + "]";
    }
}

3.写一个配置文件

driverClass=com.mysql.jdbc.Drive
url=jdbc:mysql://localhost:3306/myjdbc
user=root
password=123456

4.写一个读取配置文件和关闭数据库的方法

public class JDBCUtil {
    //声明一个属性 
    private static String driverClass;
    private static String url;
    private static String user;
    private static String password;

    //使用静态代码块加载驱动 读取配置文件
    static {
        //使用系统类来读取 配置文件
        ResourceBundle rb = ResourceBundle.getBundle("dbinfo");
        //获取文件中的数据
        driverClass  =  rb.getString("driverClass");
        password  = rb.getString("password");
        url  = rb.getString("url");
        user  = rb.getString("user");

        //获取数据库链接的方法 
        public static Connection getConnection() throws SQLException, ClassNotFoundException {  
        return DriverManager.getConnection(url,user, password);
        }

        //关闭数据库的方法   如果没有结果集需要关闭  直接传空就可以
        public static  void closeALL(ResultSet executeQuery , Statement createStatement,Connection connection) {
            if (executeQuery !=null) {
                try {
                    executeQuery.close();
                } catch (SQLException e) {
                    // TODO Auto-generated catch block

                    throw new RuntimeException("关闭失败");
                }
                //加快系统回收的速度
                executeQuery = null;
            }
            if (createStatement !=null) {
                try {
                    createStatement.close();
                } catch (SQLException e) {
                    // TODO Auto-generated catch block

                    throw new RuntimeException("关闭失败");
                }
                //加快系统回收的速度
                executeQuery = null;
            }
            if (connection !=null) {
                try {
                    connection.close();
                } catch (SQLException e) {
                    // TODO Auto-generated catch block

                    throw new RuntimeException("关闭失败");
                }
                //加快系统回收的速度
                executeQuery = null;
            }           
        }
}

写一个登陆时要查询数据库的操作

/*
 * 处理登陆的查询操作
 * 
 */     
public class DoLogin {
        //通过用户名密码  查找用户
        public static User findUser(String name ,String password) {
            String sql = "select*from users where  name='"+name+"' and password='"+password+"'";
                //创建User 
            User user = null;
            Connection connection = null;
            Statement statement = null;
            ResultSet resultSet = null;

            //查询数据库
//           1. 注册驱动 
            try {
                connection = JDBCUtil.getConnection();
                 statement = connection.createStatement();
                 resultSet = statement.executeQuery(sql);
                //只返回一条数据
                if (resultSet.next()) {
                    user = new User();
                     //使用user获取数据
                     user.setId(resultSet.getInt("id"));
                     user.setName(resultSet.getString("name"));
                     user.setPassword(resultSet.getString("password"));
                     user.setEmail(resultSet.getString("email"));
                     user.setBrithday(resultSet.getDate("birthday"));;
                }
            } catch (ClassNotFoundException | SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }finally {
                JDBCUtil.closeALL(resultSet, statement, connection);
            }
            return user;

        }
}