JaveWeb SMBMS Dao基类实现

JaveWeb SMBMS Dao基类实现

BaseDao

执行最基础的数据库操作

public class BaseDao {
    
    
    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    /*
    静态代码块,类加载的时候就初始化了
     */
    static {
    
    
        //通过类加载器读取对应的资源
        InputStream is = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");
        Properties properties = new Properties();
        try {
    
    
            properties.load(is);
        } catch (Exception e) {
    
    
            e.printStackTrace();
            ;
        }
        driver = properties.getProperty("driver");
        url = properties.getProperty("url");
        username = properties.getProperty("username");
        password = properties.getProperty("password");
    }

    //获取数据库连接
    public static Connection getConnection() {
    
    
        Connection connection = null;
        try {
    
    
            //加载驱动
            Class.forName(driver);
            connection = (Connection) DriverManager.getConnection(url, username, password);
        } catch (Exception e) {
    
    
            e.printStackTrace();
        }
        return connection;
    }
    //编写查询公共方法
    public static ResultSet execute(Connection connection,ResultSet resultSet,PreparedStatement preparedStatement,Object[] params,String sql) throws SQLException {
    
    
        preparedStatement = connection.prepareStatement(sql);  //预编译
        for(int i=0;i<params.length;i++)
        {
    
    
            preparedStatement.setObject(i+1,params[i]);
            //属性填充
        }
        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 {
    
    
        preparedStatement = connection.prepareStatement(sql);
        for(int i=0;i<params.length;i++)
        {
    
    
            preparedStatement.setObject(i+1,params[i]);
        }
        int updateRows = preparedStatement.executeUpdate();
        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();
                //GC回收
                resultSet = null;
            } catch (SQLException throwables) {
    
    
                throwables.printStackTrace();
                flag = false;
            }
        }
        if(preparedStatement!=null)
        {
    
    
            try {
    
    
                preparedStatement.close();
                //GC回收
                preparedStatement = null;
            } catch (SQLException throwables) {
    
    
                throwables.printStackTrace();
                flag = false;
            }
        }
        if(connection!=null)
        {
    
    
            try {
    
    
                connection.close();
                //GC回收
                connection = null;
            } catch (SQLException throwables) {
    
    
                throwables.printStackTrace();
                flag = false;
            }
        }
        return flag;
    }
}