We use Spring (and Spring-LDAP) for that layer. It works great, manages all
our DAO's and their resources, and then injects them into the Actions as
needed.
(*Chris*)
On Thu, Jan 7, 2010 at 10:06 AM, Jasvinder S. Bahra <
bbdl21...@blueyonder.co.uk> wrote:
> Does anyone know of any techniques that would allow a Database Access
> Object (DAO) to be used from the various actions that make up a Struts
> application?
>
> I have a DAO which, when instantiated, acquires a data source from the
> servlet container (in this case, Apache Tomcat). Thereafter, I can execute
> the various methods provided by the object which use the data source to
> execute SQL queries/statements, and return usable data in the form of
> Strings, Maps, Vectors etc, as appropriate.
>
> Instantiating the DAO in the execute() method of each of my action's
> however, seems a little inefficient. Does Struts provide any way to
> instantiate the object once and then make it available for the lifetime of
> the container (in a way that my Actions can access it)?
>
> Note please that i'm well aware that this is a somewhat non-standard
> approach to database interaction. I am intending to investigate Hibernate
> (and like) at some point, but for the time being I want to avoid such.
>
> This is the skeleton of the DAO I have in mind...
>
> ----------------------------------------------------------------------
> import java.sql.*;
> import javax.sql.*;
> import javax.naming.*;
> import javax.servlet.*;
>
> public class MyDataAccessObject {
>
> private DataSource dataSource;
> private String SQL;
>
> public MyDataAccessObject() throws Exception {
>
> try {
> Context init = new InitialContext();
> Context ctx = (Context) init.lookup("java:comp/env");
> dataSource = (DataSource) ctx.lookup("jdbc/mysqldb");
> } catch (NamingException ne) {
> throw new Exception("Cannot retrieve java:comp/env/jdbc/mysqldb",
> ne);
> }
>
> SQL = null;
> }
>
> public String getValue(String name) {
>
> Connection dbcon = null;
> PreparedStatement pstmt = null;
> ResultSet rs = null;
>
> String value = null;
>
> try {
> dbcon = dataSource.getConnection();
>
> SQL = "SELECT value FROM table WHERE name = ?";
>
> pstmt = dbcon.prepareStatement(SQL);
> pstmt.setString(1, name);
>
> rs = pstmt.executeQuery();
> while (rs.next()) {
> value = rs.getString("value");
> }
>
> rs.close();
> rs = null;
>
> pstmt.close();
> pstmt = null;
>
> dbcon.close();
> dbcon = null;
> } catch (SQLException ex) {
> log(ex);
> } catch (Exception ex) {
> log(ex);
> } finally {
> if (rs != null) {
> try { rs.close(); } catch (Exception fe1) { log(fe1); }
> rs = null;
> }
>
> if (pstmt != null) {
> try { pstmt.close(); } catch (Exception fe2) { log(fe2); }
> pstmt = null;
> }
>
> if (dbcon != null) {
> try { dbcon.close(); } catch (Exception fe3) { log(fe3); }
> dbcon = null;
> }
> }
>
> SQL = null;
> return value;
> }
>
> private void log(...) {
> // Handle logging
> }
> }
> ----------------------------------------------------------------------
>
> Thanks,
>
> Jazz
>
>
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: user-unsubscr...@struts.apache.org
> For additional commands, e-mail: user-h...@struts.apache.org
>
>
