Start off with Hans I loved the book. It was extremely helpful when I
was first writing JSP/Servlet applications. Great job!
Hans Bergsten wrote:
> EJB is overkill for most web applications, and comes at a great cost
> in terms of learning and additional implementation time. Unless you're
> very careful, it's also very easy to end up with an application with
> worse performance than if you stick to just servlets and JSP. I would
> only consider EJB if you're application has to support multiple types
> of clients (browsers, GUI apps, and other servers, for instance) and
> even then it's not a given.
This is what I thought, but having never worked with EJBs I thought I
could be wrong
> The variation of the above that I had in mind goes something like
> this. Let your Access classes use another set of classes to access
> the database. These classes encapsulate all SQL code and can return
> the data as beans that you pass on to the JSP pages. A simple example:
I like this a lot, I just have a couple questions/clarifications.
First, say I have the need to retrieve and employee from the database and
then update the information about that employee. Would I create two
Access classes (GetEmp and UpdateEmp) or would I, should I, could I
create just one Access class (EmpRepository). Also are the Access
classes singleton classes?
(Final question below)
> public class EmpListAction implements Action {
> private static final String LIST_VIEW_URL = "...";
> private GetEmpList dao = new GetEmpList(...);
> public String process(...) {
> // Validation etc.
> ...
> EmpListBean empList = dao.getEmpList(...);
> // Deal with null, if needed
> ...
> request.setAttribute(empList);
> return LIST_VIEW_URL;
> }
> }
> public class GetEmpList {
> private DataSource ds;
Are you assuming the data source is retrieved from a JNDI lookup or
returned from a singleton class or do I actually create a separate
connection pool for each access class.
> public GetEmpList(...) {
> ds = ...;
> }
> public EmpListBean getEmpList(...) {
> Connection conn = null;
> EmpListBean empList = new EmpListBean();
> try {
> conn = ds.getConnection();
> // Execute the SQL query and populate the bean with the result
> }
> catch (SQLException e) {
> // Deal with it
> }
> finally {
> if (conn != null) {
> // Closing the Connection returns it to the pool if the
> // DataSource is pooled
> conn.close();
> }
> }
> }
> }
> I hope this helps.
> Hans
> --
> Hans Bergsten [EMAIL PROTECTED]
> Gefion Software http://www.gefionsoftware.com
> JavaServer Pages http://TheJSPBook.com
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