编写数据库公共类

//操作数据库的公共类
public class BaseDao {
    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    //静态代码块
    static {
        Properties properties = new Properties();
        //通过类加载器读取对应的资源

        InputStream is = BaseDao.class.getClassLoader().getResourceAsStream("dp.properties");

            try {
                properties.load(is);
            } catch (IOException e) {
                e.printStackTrace();
        }
        driver = properties.getProperty("driver");
        url = properties.getProperty("url");
        username = properties.getProperty("username");
        password = properties.getProperty("password");
    }
    //获取数据库的链接
    public static Connection getConnection(){
        Connection connection =null;
        try {
            Class.forName(driver);
            connection = DriverManager.getConnection(url, username, password);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return connection;
    }
    //编写查询公共类
    public static ResultSet execute( Connection connection,String sql,Object[]params,ResultSet resultSet) throws SQLException {
        //预编译的sql，在后面直接执行就可以了
        PreparedStatement preparedStatement =connection.prepareStatement(sql);
        for(int i =0; i<params.length;i++){
            preparedStatement.setObject(i+1,params[i]);

        }
        resultSet =preparedStatement.executeQuery();
        return resultSet;
        }
        //编写增删改公共方法
        public static int execute(Connection connection,String sql,Object[] params,PreparedStatement preparedStatement) throws SQLException {
            //预编译的sql，在后面直接执行就可以了
            preparedStatement = connection.prepareStatement(sql);

            for(int i =0; i< params.length; i++){
                preparedStatement.setObject(i+1,params[i]);

            }

            int updateRows = preparedStatement.executeUpdate(sql);
            return updateRows;
        }
    //释放资源

    public static boolean closeResource(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet) {
        boolean flag = true;
        if (resultSet != null) {
            try {
                resultSet.close();
                resultSet = null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag = false;
            }
        }
        if (preparedStatement != null) {
            try {
                preparedStatement.close();
                preparedStatement = null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag = false;
            }
        }
        if (connection != null) {
            try {
                connection.close();
                connection = null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag = false;
            }
        }
        return flag;
    }
}