如何使用JDBC实现工具类抽取

使用JDBC实现工具类抽取需要遵循以下一般步骤：

1. 加载JDBC驱动
2. 创建数据库连接
3. 创建Statement/PreparedStatment对象
4. 执行SQL语句
5. 处理结果集
6. 释放资源

下面通过两个示例说明具体操作。

示例1：查询数据库

public class JdbcUtil {
    private static String url = "jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC";
    private static String user = "root";
    private static String password = "123456";

    static {
        try {
            // 加载驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(url, user, password);
    }

    public static void close(Connection conn, Statement stmt, ResultSet rs) {
        try {
            if (rs != null) {
                rs.close();
            }
            if (stmt != null) {
                stmt.close();
            }
            if (conn != null) {
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static List<User> getUsers(String nameLike) {
        List<User> userList = new ArrayList<>();

        Connection conn = null;
        PreparedStatement pstmt = null;
        ResultSet rs = null;

        try {
            // 获取连接
            conn = JdbcUtil.getConnection();

            // 预编译sql
            String sql = "SELECT id, name, age, gender, phone FROM user WHERE name LIKE ?";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, "%" + nameLike + "%");

            // 执行查询操作
            rs = pstmt.executeQuery();
            while (rs.next()) {
                User user = new User();
                user.setId(rs.getInt("id"));
                user.setName(rs.getString("name"));
                user.setAge(rs.getInt("age"));
                user.setGender(rs.getString("gender"));
                user.setPhone(rs.getString("phone"));
                userList.add(user);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            // 释放资源
            JdbcUtil.close(conn, pstmt, rs);
        }

        return userList;
    }
}

public class User {
    private Integer id;
    private String name;
    private Integer age;
    private String gender;
    private String phone;

    // 省略getter/setter方法
}

public class TestJdbcUtil {
    public static void main(String[] args) {
        List<User> userList = JdbcUtil.getUsers("张");
        for (User user : userList) {
            System.out.println(user);
        }
    }
}

示例2：插入数据

public class JdbcUtil {
    private static String url = "jdbc:mysql://localhost:3306/test?useSSL=false&serverTimezone=UTC";
    private static String user = "root";
    private static String password = "123456";

    static {
        try {
            // 加载驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(url, user, password);
    }

    public static void close(Connection conn, Statement stmt, ResultSet rs) {
        try {
            if (rs != null) {
                rs.close();
            }
            if (stmt != null) {
                stmt.close();
            }
            if (conn != null) {
                conn.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    public static boolean addUser(User user) {
        Connection conn = null;
        PreparedStatement pstmt = null;

        try {
            conn = JdbcUtil.getConnection();

            String sql = "INSERT INTO user(name, age, gender, phone) VALUES(?, ?, ?, ?)";
            pstmt = conn.prepareStatement(sql);
            pstmt.setString(1, user.getName());
            pstmt.setInt(2, user.getAge());
            pstmt.setString(3, user.getGender());
            pstmt.setString(4, user.getPhone());

            int count = pstmt.executeUpdate();
            if (count > 0) {
                return true;
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JdbcUtil.close(conn, pstmt, null);
        }

        return false;
    }
}

public class User {
    private Integer id;
    private String name;
    private Integer age;
    private String gender;
    private String phone;

    // 省略getter/setter方法
}

public class TestJdbcUtil {
    public static void main(String[] args) {
        User user = new User();
        user.setName("张三");
        user.setAge(20);
        user.setGender("男");
        user.setPhone("13800000000");

        boolean isSuccess = JdbcUtil.addUser(user);
        if (isSuccess) {
            System.out.println("添加成功！");
        } else {
            System.out.println("添加失败！");
        }
    }
}