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CSE 510
Web Data Engineering
The Struts Framework
Data Entry Example
UB CSE 510 Web Data Engineering
Data Entry Example - 6th Attempt
Model 1
for every JSP page p
Design Pattern
for every type of request r to p
insert in p code to implement the action requested by r
students.jsp
If request to insert student
perform SQL INSERT
If request to delete student
perform SQL UPDATE
If request to update student
perform SQL DELETE
HTML part of the JSP
INSERT STUDENT
UPDATE STUDENT
DELETE STUDENT
UB CSE 510 Web Data Engineering
Messy
JSP!
http://.../students.jsp?action=insert&...
http://.../students.jsp?action=delete&...
http://.../students.jsp?action=update&...
2
Data Entry Example - 7th Attempt
students.jsp
View
Model 2 / MVC
Design Pattern
HTML part of the JSP
INSERT STUDENT
UPDATE STUDENT
DELETE STUDENT
Controller/Actions
Model
Delete
Student
Update
Student
Insert
Student
Model Java classes export methods
that encapsulate SQL access
DB
UB CSE 510 Web Data Engineering
3
How To Develop Struts Applications
From 10 Miles High:
•  Pass high-level control to ActionServlet
–  By appropriate URL mapping in web.xml
•  Design web application workflow and code it in
struts-config.xml
•  Develop ActionForm Beans
•  Develop Action Beans
•  Develop Model Beans (not part of Struts)
•  Develop HTML and JSP pages
UB CSE 510 Web Data Engineering
4
Pass Control to ActionServlet
web.xml
<servlet>
<servlet-name>action</servlet-name>
<servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
<init-param>
<param-name>config</param-name>
<param-value>/WEB-INF/struts-config.xml</param-value>
</init-param>
<load-on-startup>2</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>action</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>
UB CSE 510 Web Data Engineering
5
Data Entry Example - 7th Attempt
Web Appliation
Workflow
menu.jsp Students (hyperlink) success showStudents.do students.jsp Insert (bu@on) StudentForm !validate InsertUpdate success insertStudent.do Update (bu@on) Delete (bu@on) StudentForm !validate InsertUpdate success StudentForm Delete updateStudent.do success UB CSE 510 Web Data Engineering
deleteStudent.do 6
Data Entry Example - 7th Attempt
Web Appliation
Workflow
menu.jsp set Students (hyperlink) Request Scope get StudentsRowSet success showStudents.do students.jsp Insert (bu@on) StudentForm !validate InsertUpdate success insertStudent.do StudentForm !validate InsertUpdate success StudentModel.insertStudent() (INSERT INTO Students…) StudentModel.getAllStudents() (SELECT * FROM Students) UB CSE 510 Web Data Engineering
DB
Update (bu@on) Delete (bu@on) StudentForm Delete updateStudent.do success StudentModel.updateStudent() (UPDATE Students…) deleteStudent.do StudentModel.deleteStudent() (DELETE FROM Students…) 7
showStudents.do Request Processing
View
get students.jsp 5
menu.jsp …/showStudents.do 2
Request Scope StudentsRowSet success set 3
AcRonServlet 4
ShowStudentsAcRon StudentModel Controller
1
struts-­‐config.xml UB CSE 510 Web Data Engineering
DB Model
8
showStudents.do Configuration
struts-config.xml
<struts-config>
...
<action-mappings>
<action
path="/showStudents"
type="dataentry.actions.ShowStudentsAction">
<forward
name="success”
path="/pages/students.jsp"/>
</action>
...
</action-mappings>
...
</struts-config>
UB CSE 510 Web Data Engineering
9
showStudents.do Action Bean
ShowStudentsAction.java
package dataentry.actions;
import
import
import
import
import
...
javax.sql.RowSet;
org.apache.struts.action.Action;
org.apache.struts.action.ActionForm;
org.apache.struts.action.ActionForward;
dataentry.model.StudentModel;
public class ShowStudentsAction extends Action {
...
UB CSE 510 Web Data Engineering
10
showStudents.do Action Bean
ShowStudentsAction.java (cont’d)
...
public ActionForward execute(
ActionMapping mapping, ActionForm form,
HttpServletRequest request,
HttpServletResponse response) throws DBException {
// retrieve all students
RowSet crsStudents = StudentModel.getAllStudents();
// store the RowSet in the request scope
request.setAttribute("crsStudents", crsStudents);
return mapping.findForward("success");
}
}
UB CSE 510 Web Data Engineering
11
showStudents.do Model Bean
StudentsModel.java
package dataentry.model;
...
public class StudentModel {
private static String selectStr
private static String insertStr
private static String updateStr
private static String deleteStr
public
public
public
public
static
static
static
static
=
=
=
=
...;
...;
...;
...;
CachedRowSet getAllStudents() {...}
void insertStudent(StudentBean student) {...}
void updateStudent(StudentBean student) {...}
void deleteStudent(StudentBean student) {...}
}
UB CSE 510 Web Data Engineering
12
showStudents.do ActionForward
students.jsp
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html"%>
...
<%-- -------- Iteration Code -------- --%>
<% RowSet crsStudents = (RowSet) request.getAttribute("crsStudents");
while (crsStudents.next()) { %>
<tr>
...
<td>
<html:text property=”middle" size="15"
value="<%=crsStudents.getString(\”middleName\")%>" />
</td>
...
</tr>
<% } %>
...
UB CSE 510 Web Data Engineering
13
insertStudent.do Request Processing
View
showStudents.do (Step 2 on Slide 8) 7
success 5
2
InsertStudentAcRon …/insertStudent.do students.jsp 6
StudentModel AcRonServlet Form ValidaRon Error 4
StudentFormInsertUpdate 1
struts-­‐config.xml UB CSE 510 Web Data Engineering
3
Controller
DB Model
14
insertStudent.do Configuration
struts-config.xml
...
<form-bean name="studentFormInsertUpdate”
type="dataentry.forms.StudentFormInsertUpdate"/>
...
<action
path="/insertStudent”
type="dataentry.actions.InsertStudentAction"
validate="true”
Not what you scope="request"
think it is! input="/showStudents.do”
name="studentFormInsertUpdate">
<forward name="success" path="/showStudents.do”
redirect="true"/>
</action>
UB CSE 510 Web Data Engineering
15
insertStudent.do ActionForm Bean
StudentFormInsertUpdate.java
package dataentry.forms;
...
public class StudentFormInsertUpdate extends ActionForm {
private
private
private
private
String
String
String
String
id = null;
first = null;
middle = null;
last = null;
public String getId() { return id; }
public void setId(String id) { this.id = id; }
...
UB CSE 510 Web Data Engineering
16
insertStudent.do ActionForm Bean
StudentFormInsertUpdate.java (cont’d)
...
/**
* Reset all properties to their default values.
*/
public void reset(ActionMapping mapping,
HttpServletRequest request) {
setId(null);
setFirst(null);
setMiddle(null);
setLast(null);
}
...
UB CSE 510 Web Data Engineering
17
insertStudent.do ActionForm Bean
StudentFormInsertUpdate.java (cont’d)
...
public ActionErrors validate(ActionMapping mapping,
HttpServletRequest request) {
ActionErrors errors = new ActionErrors();
if ((id == null) || (id.length() < 1))
errors.add("idMsgTag1",
new ActionMessage("errors.required", "UBID"));
...
return errors;
}
}
UB CSE 510 Web Data Engineering
18
insertStudent.do Action Bean
InsertStudentAction.java
public class InsertStudentAction extends Action {
public ActionForward execute(ActionMapping mapping,
ActionForm form, HttpServletRequest request,
HttpServletResponse response) throws DBException {
// cast the form
StudentFormInsertUpdate iForm =
(StudentFormInsertUpdate) form;
// insert the student
StudentModel.insertStudent(iForm);
return mapping.findForward("success");
}
}
UB CSE 510 Web Data Engineering
19
insertStudent.do ActionForward
students.jsp
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html"%>
The corresponding ...
AcRonForm bean <!-- in case form validation fails -->
<html:errors />
will also be used to ...
populate HTML form <tr>
<html:form action="/insertStudent">
<td><html:text property="id" size="10" /></td>
<td><html:text property="first" size="15" /></td>
<td><html:text property="middle" size="15" /></td>
<td><html:text property="last" size="15" /></td>
<td><html:submit value="Insert" /></td>
<td><html:reset /></td>
</html:form>
</tr>
...
UB CSE 510 Web Data Engineering
20
struts-config.xml Structure
<struts-config>
<!-- ========================= Form Bean Definitions -->
<form-beans>...</form-beans>
<!-- ================== Global Exception Definitions -->
<global-exceptions>...</global-exceptions>
<!-- ==================== Global Forward Definitions -->
<global-forwards>...</global-forwards>
<!-- ==================== Action Mapping Definitions -->
<action-mappings>...</action-mappings>
<!-- ================= Message Resources Definitions -->
<message-resources parameter="MessageResources" />
</struts-config>
UB CSE 510 Web Data Engineering
21
Global Exceptions
struts-config.xml
<!-- ==================== Global Exception Definitions -->
<global-exceptions>
<exception key="error.db"
type="dataentry.db.DBException"
path="/pages/dbException.jsp"/>
</global-exceptions>
UB CSE 510 Web Data Engineering
22
Global Exceptions
DBException.java
package dataentry.db;
public class DBException extends Exception {
public DBException() {
super();
}
public DBException(String message) {
super(message);
}
}
UB CSE 510 Web Data Engineering
23
Global Exceptions
StudentModel.java
public static void insertStudent(
StudentFormInsertUpdate student) throws DBException {
try {
...
} catch (SQLException ex) {
throw new DBException(ex.getMessage());
} catch (NamingException ex) {
throw new DBException(ex.getMessage());
}
}
UB CSE 510 Web Data Engineering
24
Global Exceptions
InsertStudentAction.java
public class InsertStudentAction extends Action {
public ActionForward execute(ActionMapping mapping,
ActionForm form, HttpServletRequest request,
HttpServletResponse response) throws DBException {
...
StudentModel.insertStudent(...);
...
}
}
UB CSE 510 Web Data Engineering
25
Global Exceptions
dbException.jsp
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html"%>
<html>
<body>
<h2>Database Exception</h2>
...
<h3>Here is the message generated by the thrown database
exception:</h3>
<p><html:errors /></p>
</body>
</html>
UB CSE 510 Web Data Engineering
26
Global Forwards
struts-config.xml
<!-- ====================== Global Forward Definitions -->
<global-forwards>
<forward name="showStudents" path="/showStudents.do"/>
</global-forwards>
menu.jsp
<%@ taglib uri="http://struts.apache.org/tags-html" prefix="html"%>
<b>Data Entry Menu</b>
<ul>
<li><html:link forward="showStudents">Students</html:link></li>
...
</ul>
UB CSE 510 Web Data Engineering
27
Message Resources
MessageResources.properties
# -- app -app.title=Struts Data Entry Application
...
students.jsp
<%@ taglib uri="http://struts.apache.org/tags-bean" prefix="bean"%>
<html>
<head>
<title><bean:message key="app.title" /></title>
</head>
...
</html>
UB CSE 510 Web Data Engineering
28
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