A follow up to the J2EE DAO Pattern: I found that it helps a lot using externalized SQL statements, i.e., build SQL statements in an XML file with your own DTD. It's point #3 in that blueprint. However, to this date I haven't found any good examples online. Also I sent an email to the blueprint team asking how to pass multiple arguments(for example, a collection.) If anyone looked at the 'petsstore' example that comes with the blueprints, you would notice that the number of parameters are hardcoded all the time in the Dao related .xml files. So still I don't know how to pass a collection as the 'input-mapping.'
I am just wondering if anyone is using externalized SQL statements in their application as well. What's your view on it? Thanks! -----Original Message----- From: Sloan Bowman [mailto:[EMAIL PROTECTED] Sent: June 18, 2003 9:49 PM To: Struts Users Mailing List Subject: Re: Struts and database I will do my best to explain this but I will also point you in the right direction. First off you need to read the Java Blueprints on using DAO with J2ee. This will teach you the best methods of using Databases by using the DAO to encapsulate the DataSource . Here is the link to the Java Blueprints http://java.sun.com/blueprints/corej2eepatterns/Patterns/DataAccessObject.html read this complete document and it will help you out alot with how you should use your databases in your applications. Lets use an example say for a User requesting a item from the online store for our example. First you build the ActionForm which stores the data sent by the form. The ActionForm is passed through the FrontController which in turn dispatches you to the correct Action. In our case the Action will be using methods from a class which contains all of your Buisness logic. Form example, we have a ItemDAO which has a method getItem(int itemNum). This method returns a ItemBean which stores all of the information about that item. This Bean you are using to store all of the information is called a State Bean (if I remember right, corrections are welcome). When you get the ItemBean returned from the method getItem(int itemNum) you can then add it to your session/request etc.. for example you could do request.setAttribute("itemBean", itemBean). Now once you return the ActionForward in the Action (Example: mapping.findForward("success")) the itemBean will be part of the request and you acn access these properties in the View using jsp, velocity etc.. I hope this helps you out. --Sloan p.s. Sorry for the type o's I didn't proof read >Hi! Would anyone give me some examples of database programming, which >lead from retrieving data to rendering view. (I mean real database, not >from XML files), e.g. any web site with source, or even better, some >simple example? I am very confused on how to use beans from the model. >If there any book that focus on database programming? I have been >searching on the web, but unable to find. > >Andy Cheng >[EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
