Struts 1.x Dispatch Action Example

DispatchAction provides a mechanism for grouping a set of related functions into a single action. This avoid by creating separate actions for each functions. In this example lets see how to group a set of related actions like add and del into a single action called DispatchObjectAction.

The class DispatchAction extends org.apache.struts.actions.DispatchAction. This class does not provide an implementation of the execute() method as the normal Action class does. The DispatchAction uses the execute method to manage delegating the request to the individual methods based on the incoming request parameter. For example if the incoming parameter is "method=add", then the add method will be invoked. These methods should have similar signature as the execute method.

Step - 1.0 Create Directory Structure

Create the folder structure and add struts libraries under the lib folder which is inside the WEB-INF.

Step - 2.0 Create Action Form

Create a java class called “DispatchObjectForm.java” by extending struts Action Form. This is use to hold the data later.

package com.form;

import java.io.Serializable;

import org.apache.struts.action.ActionForm;

public class DispatchObjectForm extends ActionForm implements Serializable{

/**

private static final long serialVersionUID = 1L;

private String actionName;

private String message;

public String getActionName() {

return actionName;

}

public void setActionName(String actionName) {

this.actionName = actionName;

}

public String getMessage() {

return message;

}

public void setMessage(String message) {

this.message = message;

}

Step - 3.0 Create Action Class

Create a class called “DispatchObjectAction.java” by extending the DispatchAction. The DispatchAction uses the execute method to manage delegating the request to the individual methods based on the incoming request parameter.

package com.action;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.ActionForm;

import org.apache.struts.action.ActionForward;

import org.apache.struts.action.ActionMapping;

import org.apache.struts.actions.DispatchAction;

import com.form.DispatchObjectForm;

public class DispatchObjectAction extends DispatchAction{

public ActionForward add(ActionMapping mapping, ActionForm form,

HttpServletRequest request, HttpServletResponse response)throws Exception{

DispatchObjectForm objectForm = (DispatchObjectForm)form;

objectForm.setActionName("Add");

objectForm.setMessage("Inside the Add Dispatch");

return mapping.findForward("success");

}

public ActionForward del(ActionMapping mapping, ActionForm form,

HttpServletRequest request, HttpServletResponse response)throws Exception{

DispatchObjectForm objectForm = (DispatchObjectForm)form;

objectForm.setActionName("Delete");

objectForm.setMessage("Inside the del Dispatch");

return mapping.findForward("success");

}

Step - 4.0 Create JSP view page

Create a jsp called “index.jsp” This access the Action Form object via Struts tag library and print the Form properties.

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>

<%@ taglib uri="/WEB-INF/tld/struts-html.tld" prefix="html"%>

<%@taglib uri="http://struts.apache.org/tags-bean" prefix="bean"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Dispatch Action Example</title>

</head>

<body>

<html:form action="DispatchAction" method="add">

<table>

<bean:write name="DispatchObjectForm" property="actionName"/>

</td></tr>

<bean:write name="DispatchObjectForm" property="message"/>

</td></tr>

<tr>

</tr>

</table>

</html:form>

</body>

</html>

Step - 5.0 Create struts-config.xml

Create a struts-config.xml file for the Struts configuration details, and put it into the WEB-INF/config folder.

Define the form bean name (FirstExampleForm).

Defien the Action mapping controller (FirstExampleAction), match the /firstExample web path to FirstExampleAction.

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE struts-config PUBLIC

"-//Apache Software Foundation//DTD Struts Configuration 1.3//EN"

"http://jakarta.apache.org/struts/dtds/struts-config_1_3.dtd">

<struts-config>

<form-beans>

<form-bean name="DispatchObjectForm" type="com.form.DispatchObjectForm"/>

</form-beans>

<action-mappings>

<action input="/WEB-INF/jsp/index.jsp"

parameter="method"

name="DispatchObjectForm"

path="/DispatchAction"

type="com.action.DispatchObjectAction">

</action>

</action-mappings>

</struts-config>

Step - 6.0 The web application deployment descriptor ( web.xml )

In web.xml file, configure the Struts ActionServlet instance and map it with url-pattern “*.do”, so that the container is aware of all the “*.do” pattern will redirect to Struts ActionServlet.

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">

<display-name>StrutsBasicExampleDispatchAction</display-name>

<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/config/struts-config.xml</param-value>

</init-param>

<load-on-startup>1</load-on-startup>

</servlet>

<servlet-mapping>

<servlet-name>action</servlet-name>

<url-pattern>*.do</url-pattern>

</servlet-mapping>

</web-app>

Step - 7.0 Run the application on server and out put will be

http://localhost:8080/StrutsBasicExampleDispatchAction/DispatchAction.do?method=add

IT Education Guidance - Struts

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Tuesday, August 20, 2013

Struts 1.x Dispatch Action Example

Struts 1.x Dispatch Action Example