Database access class best practices

Question

Im creating a simple DBHelper for my postgre DB using a JDBC driver.

Im wondering what are the best practices?

For example, are methods like initConnection() closeConnection() or any other, should be static one? Like:

void foo{
    DBHelper.initConnection();
    // do some logic, maybe:
    // Data someData = DBHelper.getSomeData();
    DBHelper.closeConnection();
}

Or maybe better if i will create a DBHelper object and call method for object. Like:

void foo2{
    DBHelper dbhelper = new DBHelper();
    dbhelper.initConnection();
    // do some logic, maybe:
    // Data someData = dbhelper.getSomeData();
    dbhelper.closeConnection();
}

Is it matter at all?

Do i need always check if connection is open before i will try to retrive some data? What if it is close? And always try to close it in finally block?

EDIT: in answer to @Kayaman comment:

So my foo method like this?

 void foo3{
    Connection conn = DBHelper.getConnection();
    // do some logic, maybe:
    // Statement statement = conn.createStatement();
    // some stmt work
    conn.close() //do i need check if stmt is closed before? 
}

That will make my DBHelper class usefull only to getting connection. There will be no logic inside? (like GetInterestingRecords() or GetRecordsWithId(30) ?

Answer 1

您是否考虑过在服务器配置文件（如果是Web应用程序）中定义连接属性，并且在整个应用程序生命周期中都打开了会话？

Answer 2

Before implementing DBHelper you should check if some java libraries may satisfy your needs. If you take a look at this there are listed some libraries that seem to fit your problem.

If you decide to go on with your own custom implementation I suggest to make DBHelper a normal class with no static methods for managing the connections; the main reason is that with static methods you cannot manage multiple (ie connections to different databases) db connections at the same time. If you are using a java 7 implementation in your onw library you could also implement tha AutoClosable inferface in order to better manage the resource you library is managing.