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Implementation
This section describes how the BC4J-VSM uses Struts and JBO
tags together with the BC4J framework to display a list of orders to a mall
customer.
The Struts technologies used are:
-
Struts Controller Sevlet - MVC Controller servlet which controls all access
to application.
-
Struts Action - A java class designated to handle
a Struts application Action which is in the form of a URL request.
-
Struts ActionForm (Form Bean) - A Java class which
represents the contents of an HTML form. It also provides a validation method.
-
Struts "Bean" and "HTML" tag
libraries - JSP tag libraries which allow for interaction with Struts components
from JSP.
-
Struts-Config.xml - The master configuration file
for all Struts applications.
-
ApplicationResources.properties - A resource
file which can store multi-lingual messages and data for a Struts application.
JDeveloper provides these facilities to develop a web application
based on Jakarta Project's Struts framework that you deploy as either Java servlets
or JavaServer Pages.
-
The Struts Configuration Editor lets you manage
the struts-config.xml file, which defines the ActionMappings for your application.
The Struts controller uses the mappings to turn HTTP requests into application
actions.
-
The various Struts dialogs in the Web Tier - Struts
category of the New Gallery let you add the Struts framework components
to a generic JSP web application. When you add Struts to a generic JSP project,
you may also work with BC4J through its request processor (BC4JRequestProcessor).
-
The BC4J Struts JSP Web Application Wizard in the
Web Tier - Struts-Based JSP for Business Components category of the New
Gallery lets you generate an entire databound web application. The generated
JSP pages rely on a BC4J-specific action controller that functions with
a model implemented by Oracle's data access layer, Business Components for
Java (BC4J).
For work with Struts and BC4J frameworks,
JDeveloper provides a set of wizards that resemble the standard (non-Struts)
BC4J JSP page wizards, but they generate a web application that relies on a
BC4J-specific request processor for use in the Struts MVC paradigm. The wizard-generated
code implements the BC4J framework and provides full database access, state
management, and transaction control to web application clients.
For example, the BC4J JSP Struts Web
Application Wizard helps you create an entire web application based on a Business
Components project. Standard actions are implemented using the Struts framework
and a Struts version of the component tags from the BC4J Data Tags custom tag
library.
All Struts actions begin with a URL that is submitted to the
JSP request object when the end user clicks a Struts-defined link. The link
must be of the form actionPathName.do, where the extension
.do causes the ActionServlet to locate the corresponding
action in the struts-config.xml configuration file.
The runtime process for handling actions in the Struts framework
implemented by the BC4J component tags is:
- User clicks a link that submits
a
.do parameter.
ActionServlet maps the request URI to the
Action class through the definition in struts-config.xml.- The action class processes the request
through a
The following HTML code (with jbo
tags) comes from mallUsers/allOrders.jsp. It includes an HTML anchor
tag that defines a link to manageorder.do.
<%UserOrdersRow row = null;%>
<jbo:RowsetIterate datasource="OrderTrackingService.UserOrders">
<jbo:Row id="currRow" action="Active"
datasource="OrderTrackingService.UserOrders"/>
<%
row = (UserOrdersRow)currRow;
%>
<TR>
...
<TD align="center" class="BlackText" width="82">
<A href="manageorders.do?jboRowKey=
<%=row.getKey().toStringFormat(true)%>
&jboEvent=getOrders"
class="Link">Details</A>
</TD>
</TR>
</jbo:RowsetIterate>
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The following XML code comes form
struts-config.xml. It defines the action manageorders,
specifying a Java class (OrderEditAction) and method (getAllOrders)
to handle the action, and associated JSPs (including allOrders.jsp).
...
<action path="/manageorders" parameter="jboEvent"
scope="request"
type="oracle.otnsamples.vsm.controllers.user.OrderEditAction"
validate="false">
<set-property property="releasemode" value="Stateless"/>
<set-property property="application" value="OrderTrackingService"/>
<set-property property="viewobject" value="UserOrders"/>
<forward name="getOrders" path="/jsps/mallUser/myOrders.jsp"/>
<forward name="getAllOrders" path="/jsps/mallUser/allOrders.jsp"/>
</action>
...
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The following Java code comes from
OrderEditAction.java. It implements the action method defined in
the Struts configuration file (shown above). It imports Struts action classes
(org.apache.struts.action.*) and BC4J classes (oracle.jbo.*)
to gain access to those frameworks' functionality. This code calls BC4JContext.getContext
to get context data from the HTTP request parameter, then uses this data to
instantiate the UserOrders View Object, a BC4J component. Then the code uses
the View Object to execute a query and iterate through the results.
package oracle.otnsamples.vsm.controllers.user;
...
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.ActionError;
import org.apache.struts.action.ActionErrors;
import oracle.jbo.client.JboUtil;
import oracle.jbo.ViewObject;
import oracle.jbo.html.struts11.actions.EditAction;
import oracle.jbo.html.struts11.BC4JUtils;
import oracle.jbo.RowIterator;
import oracle.jbo.Key;
import oracle.jbo.html.BC4JContext;
import oracle.jbo.Row;
import oracle.otnsamples.vsm.views.common.UserOrders;
import oracle.otnsamples.vsm.views.common.UserOrdersRow;
import oracle.otnsamples.vsm.views.common.OrderItemsRow;
import oracle.otnsamples.vsm.views.common.ItemRow;
import oracle.otnsamples.util.Utilities;
...
public ActionForward getAllOrders(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response) {
BC4JContext context = BC4JContext.getContext(request);
try {
String uName = (String)request.getSession().getAttribute("USER_NAME");
UserOrders orders = (UserOrders)context.getViewObject();
orders.setUserName(uName);
orders.executeQuery();
UserOrdersRow row = null;
double total = 0.0;
RowIterator iter = null;
OrderItemsRow currRow = null;
while(orders.hasNext()) {
row = (UserOrdersRow)orders.next();
total = 0.0;
iter = row.getOrderItems();
while(iter.hasNext()) {
currRow = (OrderItemsRow)iter.next();
total += currRow.getUnitPrice().doubleValue() *
currRow.getQuantity().doubleValue();
}
request.setAttribute(row.getId().getSequenceNumber().stringValue(),
new Double(total));
}
orders.reset();
}
catch(Exception ex) {
...
}
return BC4JUtils.getForwardFromContext(context, mapping);
}
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The other tutorials in this series
describe various application features and explain how they were implemented.
| 
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