Struts 2 Session Scope
In this section, you will learn to create an AJAX
application in Struts2 Framework that displays some messages with session.
The current application displays a jsp page having the
two text fields.
If the user enters nothing in the text fields and
submit the form it displays an error message "nothing entered".
If the user enters some text in the WELCOME1 field, then the corresponding attribute is
set to "welcome1".
If the user leaves the WELCOME1 field
empty and enters some text in the WELCOME2 field, then the corresponding attribute is set
to "welcome2".
This application is created with AJAX in Struts2 Framework. Before we
start
the things, we need to
do the following:
- Download Struts2 from Apache.org
- Deploy the jars under Tomcat server WEB-INF/lib
- Rename the jars containing "plug-in" (this
is very important as our application doesn't need any plugin's and Tomcat
class loader sometimes fails to find the class files associated with the
plugin's)
- Make sure the Tomcat server is the latest (Tomcat
5.5.0 and above)
- Download xwork-2.0.4.jar from opensymphony.com
as it is not available with the Struts2 distribution.
The struts.xml file contains the information
about the files,
constants, packages and actions to be included. The <include file> tag
provides standard
information provided by Struts2. The <constant> tags are also there, you may set the struts.devMode constant to true, but it is not necessary. The
package tag specifies a name, namespace and extends attributes.
Pay attention to
namespace as it affects the URL you have to type in the browser. If you give a
namespace say "/roseindia" then your URL will be "http://localhost:8080/struts2tutorial/roseindia/showAjaxTestActionForm.action".
To make it simpler as we don't have many packages we
have set the namespace to blank so that we need only use the URL "http://localhost:8080/struts2tutorial/roseindia/showAjaxTestActionForm.action"
The action with name showAjaxTestActionForm
shows in the view AjaxTest.jsp. Note that the pages don't have to be in
the classpath.
struts.xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
<!-- Rose India Struts 2 Tutorials -->
<constant name="struts.enable.DynamicMethodInvocation" value="false" />
<constant name="struts.devMode" value="true" />
<include file="struts-default.xml"/>
<package name="roseindia" namespace="/roseindia" extends="struts-default">
<action name="showAjaxTestActionForm">
<result>/pages/AjaxTest.jsp</result>
</action>
<action name="AjaxTestAction" class="net.roseindia.SampleForm">
<result name="error">/pages/AjaxTest.jsp</result>
<result name="success">/pages/AjaxTest.jsp</result>
<result>/pages/AjaxTest.jsp</result>
</action>
<!-- Add actions here -->
</package>
<!-- Add packages here -->
</struts> |
The action AjaxTestAction is the form action
attribute. It is associated with the support class net.roseindia.SampleForm
which is in the class path. The result tags mean as follows:
- If the class returns "error" then show the
error message set in the Java class in the view.
- If the class returns "success" then update
the view.
- If the class returns nothing then update the view.
The JSP file contains a form, two text fields and a
submit button. The <s:actionerror>, <s:fielderror> and
<s:actionmessage> tags will display the errors associated while
processing this form. The <s:div id="loginDiv" theme="ajax">
tag prints a message at the top of the view indicating which textfield has been
set. It displays a message from the session's set attribute.
Here is the code for the JSP form: AjaxTest.jsp
<%@ taglib prefix="s" uri="/struts-tags" %>
<html>
<head>
<s:head theme="ajax" debug="true"/>
</head>
<body>
<s:div id="loginDiv" theme="ajax">
<h3> Your Session: <s:property value="#session.ret" /></h3>
<div style="width: 300px;border-style: solid">
<s:form action="AjaxTestAction" validate="false">
<tr>
<td colspan="2">
Run Test
</td>
</tr>
<tr>
<td colspan="2">
<s:actionerror />
<s:fielderror />
<s:actionmessage/>
</td>
<s:textfield name="welcome1" label="WELCOME1"/>
<s:textfield name="welcome2" label="WELCOME2"/>
<s:submit value="Submit" theme="ajax" targets="loginDiv"
notifyTopics="/AjaxTestAction"/>
</tr>
</s:form>
</div>
</s:div>
</body>
</html>
|
The following java class extends the ActionSupport
class that implements the SessionAware interface. This way we can get the
best of the both worlds because SessionAware will add attributes to the
session that can be accessed from the JSP. In our case it will be the "ret"
attribute. The setter and getter methods are straightforward.
Here is the code of SampleForm.java:
package net.roseindia;
import com.opensymphony.xwork2.ActionSupport;
import org.apache.struts2.interceptor.SessionAware;
import java.util.Map;
public class SampleForm extends ActionSupport implements SessionAware{
//Fields that hold data
private String Welcome1="";
private String Welcome2="";
private Map session;
public String execute() throws Exception {
if (getWelcome1().trim().equals("") && getWelcome2().trim().equals("")){
addActionError("nothing entered");
return ERROR;
}
if (!getWelcome1().trim().equals("") && !getWelcome2().trim().equals("")){
addActionMessage("Both have data!");
return ERROR;
}
if (!getWelcome1().trim().equals("")){
getSession().put("ret", "welcome1");
addActionMessage("Welcome 2 is empty!");
return ERROR;
}
if (!getWelcome2().trim().equals("")){
getSession().put("ret", "welcome2");
addActionMessage("Welcome 1 is empty!");
return ERROR;
}
return SUCCESS;
}
public void setWelcome1(String s) {
this.Welcome1= s;
}
public String getWelcome1() {
return Welcome1;
}
public void setWelcome2(String s) {
this.Welcome2= s;
}
public String getWelcome2() {
return Welcome2;
}
public void setSession(Map session) {
this.session = session;
}
public Map getSession() {
return session;
}
}
|
Compile the class, start the Tomcat, and test the
application by typing the following URL on the address bar of web browser: "http://localhost:8080/struts2tutorial/roseindia/showAjaxTestActionForm.action"
Output:
When this application executes you get a page as
shown:
If you leave the "WELCOME1" and "WELCOME2"
field empty then a message is displayed with session as shown below:
After clicking the "Submit" button then you get:
If you leave the "WELCOME1" field empty and
just fill the "WELCOME2" field then a message is displayed with
session as shown below:
If you fill the "WELCOME1" field and just
leave the "WELCOME2" field empty then a message is displayed with
session as shown below:
If you fill both field then you get:
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