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STRUTS FRAMEWORK

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Apache Struts• Struts Frame work is the implementation of

Model-View-Controller (MVC) design pattern for the JSP.

• Struts is maintained as a part of Apache Jakarta project

• Struts is open source.

What is Model-View-Controller (MVC) Architecture?

• Model-View-Controller architecture is all about dividing application components into three different categories Model, View and the Controller.

• Components of the MVC architecture has unique responsibility and each component is independent of the other component.

• Changes in one component will have no or less impact on other component.

MVC ARCHITECTURE

Struts Architecture

• Struts is an open source framework used for developing J2EE web applications using Model View Controller (MVC) design pattern.

• It uses and extends the Java Servlet API to encourage developers to adopt an MVC architecture.

Components

Struts 2 Core components are Action handler, Result Handler and Custom Tags. Action handler

Action handler interacts with other layers.Result Handler

Result handler actually dispatches the response to view.

Custom TagsCustom Tags are used render the dynamic content.

Components

• InterceptorsThe Interceptors are used to specify the "request-processing lifecycle" for an action. Interceptors are configured to apply the common functionalities like workflow, validation etc.. to the request. Interceptors code is executed before and after an Action is invoked

How Struts Works

• In struts JavaServerPages (JSP) are used to design the dynamic web pages.

• In struts, servlets helps to route request which has been made by the web browsers to the appropriate ServerPage.

• The use of servlet as a router helps to make the web applications easier to design, create, and maintain.

STRUTS ARCHITECTURE

Process flowUser Sends request.FilterDispatcher determines the appropriate

action.Interceptors are applied. Execution of Action. Output rendering. Return of Request(reverse order). Display the result to user.

Things to download before you start struts

• Requirements (Downloads)– JDK ver. 1.5 and above.– Tomcat 5X and above(Tomcat ver.6 is better)– Eclipse ver. 3 and above.– Apache struts2 jar files needed• common-logging-1.0.4.jar• freemarker-2.3.8.jar• ognl-2.6.11.jar• struts2-core-2.0.12.jar• xwork-2.0.6.jar

Example program using struts

We suppose to create a login application using struts.

Getting started

• Open eclipse and go to fileNewDynamic project in the new project wizard screen.

• You will have a screen consisting of some wizards as shown in the next slide.

• After giving the project name click Finish.

Getting started

Getting started

• Once you created the project, you can see its structure in the project folder.

• After these processes, now copy all the jar files listed in the previous slides to WebContentWEB INF

Structure of project folder

Import jar files

Mapping program to xml

• Open web.xml file which is under WEB-INF folder and copy-paste the following program.

Mapping program to xml• <?xml version="1.0" encoding="UTF-8"?>• <web-app id="WebApp_9" version="2.4"• xmlns="http://java.sun.com/xml/ns/j2ee"• xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"• xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">• • <display-name>Struts2 Application</display-name>• <filter>• <filter-name>struts2</filter-name>• <filter-class>• org.apache.struts2.dispatcher.FilterDispatcher• </filter-class>• </filter>• <filter-mapping>• <filter-name>struts2</filter-name>• <url-pattern>/*</url-pattern>• </filter-mapping>• <welcome-file-list>• <welcome-file>Login.jsp</welcome-file>• </welcome-file-list>• • </web-app>

Class and methods

• Create a class called LoginAction in com.test.struts2package.

• Note that, above action class contains two fields, username and password which will hold the values from form and also contains an execute() method that will authenticate the user. In this simple example, we are checking if username is admin and password is admin123.

• Also note that unlike Action class in Struts1, Struts2 action class is a simple POJO class with required attributes and method.

• The execute() method returns a String value which will determine the result page. Also, in Struts2 the name of the method is not fixed. In this example we have define method execute(). You may want to define a method authenticate() instead.

Create resource file

• Resource bundle is a java entity that helps in putting the static content away from the source file.

• Here we should define an application file and should be named as ApplicationResources.properties files

• To create it the method is on the next slide

Resource folder

Resource folder

• Click that source folder option and you will be having a following screen.

• And set the source folder as Resources folder.• In that folder create a file called

ApplicationResources.properties .

Resources

• Copy these contents into ApplicationResources.properties

• label.username= Username• label.password= Password• label.login= Login• error.login= Invalid Username/Password. Please try again.

Jsp files to run the application

Login.jsp

Jsp files(2)

Welcome.jsp

Jsp(3)

• Above programs are made in the folder Struts2_HelloworldWebContentWEB-INFLogin.jsp.

• Struts2_HelloworldWebContentWEB-INFWelcome.jsp.

Create a struts file

• Struts2_HelloWorldJava Resourcesresourcescreate file struts.xml

• Copy the following content into struts.xml

Struts.xml

Copy the above text into struts.xml.

Important note

• Our LoginAction.java class is having a method called execute(). If the name of the method is different, e.g. authenticate(). Then we should specify the name of the method in the action tag.

Action

• You can see <s: submit method command in the program Login.jsp

Running the application• Now select Login.jsp then select the run on

server command.• After selecting the command, you will be

having a server lists out of that, select apache-tomcat server version.6. then run the program.

• You will be having the following screen on your browser.

Screens(1)

Enter user_name as admin and password as admin123

Screen(2)

If you login successfully, you will get a screen as output.

Screen(3)

If you login into the application as a wrong user, the appearing screen will be like this. You are instructed to renter the user and password again

That’s all folks

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