Struts

BB: Struts ATS Application Programming: Java Programming

© Accenture 2005 All Rights Reserved

Course Code #Z16325

Objectives

This review session will cover Struts. Included in this review: What is Struts  Struts Framework Features  Struts Architecture  Struts Model Component  Struts View Component  Struts Control Component  Struts Tag Libraries (HTML, Bean, Logic)  ActionForm  ActionServlet  Action ©2005 Accenture All Rights Reserved.  © AccentureActionMapping 2005 All Rights Reserved 

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Detailed in this review:

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Overview

The Framework of the Struts How It is Implemented

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What is Struts? 

An open source development framework for building web applications.

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Based on Model-View-controller (MVC) design paradigm

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Implementation of JSP Model 2 Architecture

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2nd Release candidate of version 1.1 released

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Consists of 8 Top-Level Packages

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Approx 250 Classes and Interfaces

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Struts Framework Features

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Model 2 - MVC Implementation

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Internationalization (I18N) Support

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Rich JSP Tag Libraries

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Based on JSP, Servlet, XML, and Java

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Supports Java’s Write Once, Run Anywhere Philosophy

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Supports different model implementations (JavaBeans, EJB, etc.)

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Supports different presentation implementations (JSP, XML/XSLT, etc.)

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Struts Architecture

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Struts Architecture

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Struts Architecture 

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Central controller mediates application flow and delegates to appropriate handler. Handlers are tied to model components. Model encapsulates business logic. Control forwarded back through the Controller to the appropriate View. The forwarding can be determined by consulting a set of mappings in configuration file, which provides a loose coupling between 8 ©2005 Accenture All Rights Reserved. the View and Model.

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Struts “Model” Components   

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No built-in support for the model. No model components provided. Framework supports any component model. (JavaBeans, EJB, Corba, etc.) Should always decouple the application from a specific model implementation.

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Struts “View” Components        

JavaServer Pages HTML JavaScript and Stylesheets Multimedia Files Resource Bundles JavaBeans (Part of model used by views) JSP Custom Tags ActionForms ©2005 Accenture All Rights Reserved.

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Struts “Control” Components 

ActionServlet - Extends javax.servlet.http.HttpServlet - Receives all framework requests - One ActionServlet instance per web application

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RequestProcessor - One instance per application module - Processes all requests for module - Invokes properAction instance - Default implementation provided by framework (can extend if necessary)

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ActionClasses Extends org.apache.struts.action.Action Overrides the execute() method Acts as a bridge between user-invoked URI and a business method (Command pattern) Returns information about which view should be rendered next Part of the Controller, not the Model ©2005 Accenture All Rights Reserved.

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Struts Tag Libraries 

THE HTML TAG LIBRARY - Tags used to create Struts input forms - Examples include (checkbox, image, link, submit, text, textarea)

< b> Shipping Address < td> Address: < td> City: < td> State: < td> Postal:

< html: text name=" checkoutForm" property=" shippingAddress"/>

< html: text name=" checkoutForm" property=" shippingCity"/>

< html: text name=" checkoutForm" property=" shippingState"/>

< html: text name=" checkoutForm" property=" shippingPostal"/> ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved 12 HTML Tags (cont.)      Acts as a bridge between JSP view and other components. Input forms are important for gathering data. Most of the actions of the HTML taglib involve HTML forms. Error messages, hyperlinking, internationalization. HTML tags must be nested within a form tag. Inform handler which bean to use for initializing ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved displayed values. – 13 Struts Tag Libraries  - THE BEAN TAG LIBRARY Tags used for accessing JavaBeans and their properties Examples include (define, message, write) Current Total: $ ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved 14 Bean Tags (cont.)    Tags for accessing beans and their properties Enhancements to <jsp:useBean> Convenient mechanisms to create new beans based on the value of: – – – Cookies Request Headers Parameters ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved 15  Struts Tag Libraries THE LOGIC TAG LIBRARY – – – – Managing conditional generation of output text Looping over object collections for repetitive generation of output text Application flow management. Examples include (empty, lessThan, greaterThan, redirect, iterate) Logic Tag Library Example … … ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved 16 Logic Tags (cont.)  Provides presentation logic tags for:  Value comparisons –  Substring matching –  match, notmatch Presentation logic –  Include: = != <= >= < > forward, redirect Collections – iterate ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved 17 ActionForm      Java class that extends the org.apache.struts.action.ActionForm. Captures user data from the Http request. Stores the data temporarily. Acts as a “firewall” between the presentation tier and the application. Provides the ability to validate the user input. ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved 18 ActionForm (cont.)  Provided by developer    Define an ActionForm bean (that is, a Java class extending the ActionForm class) for the input form Extend Struts-provided ActionForm class Define it in servlet-config.xml file – –  name attribute of class Contains only property getter and property setter methods for each field - no business logic ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved 19 ActionForm (cont.) Example package com.jds.apps.hr.employee.form; import javax.servlet.http.HttpServletRequest; import org.apache.struts.action.ActionError; import org.apache.struts.action.ActionErrors; import org.apache.struts.action.ActionMapping; public class EmployeeInfoForm extends AbstractEmployeeForm { public ActionErrors validate(ActionMapping mapping, HttpServletRequest request) { ActionErrors errors = new ActionErrors(); // Last Name: if it's empty, has a special character, or exceeds it's maximum length if( objectIsNull.validate(this.getLastName() ) || stringIsEmpty.validate( this.getLastName() ) ){ errors.add("lastName", new ActionError("field.null","Last Name")); } else if( !stringIsValidD.validate( this.getLastName() ) ){ errors.add("lastName", new ActionError("field.invalid.specialcharacter", "Last Name", allowedCharactersD)); ©2005 Accenture All Rights Reserved. } © Accenture 2005 All Rights Reserved else if( !stringLengthIsValidFifty.validate( this.getLastName() ) ){ 20 ActionServlet What Does ActionServlet Do?  Performs the role of Controller – – – – Process user requests Determine what the user is trying to achieve according to the request Pull data from the model (if necessary) to be given to the appropriate view, and Select the proper view to respond to the user ©2005 Accenture All Rights Reserved.  Delegates most of this grunt work to Action © Accenture 2005 All Rights Reserved 21 Action Class Focus on control flow   Process client request by calling other objects (BusinessLogic beans) inside its execute() method Returns an ActionForward object that identifies where control should be forwarded – – – – JSP Tile definition Velocity template Another Action ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved 22 Action Class (cont.) What is Action Class?  Java class that does the “work” of your application – –  Handle request Perform business logic Can be simple or sophisticated – – Simple action class does handle business logic by itself Sophisticated ones invoke Model components  ©2005 Accenture All Rights Reserved. 23 Action class functions as a Facade pattern in this case © Accenture 2005 All Rights Reserved Action Class (cont.) Example package com.jds.apps.hr.employee.action; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.struts.action.ActionError; import org.apache.struts.action.ActionErrors; import org.apache.struts.action.ActionForm; import org.apache.struts.action.ActionForward; import org.apache.struts.action.ActionMapping; public class EmployeeAddAction extends AbstractAction { public ActionForward execute(ActionMapping actionMapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception { EmployeeInfoForm viewForm = (EmployeeInfoForm) form; // Determine action, if edit or view mode ©2005 Accenture All Rights Reserved. UserBean userBean = this.getUserBean(request); String userBean.getUserType(); © Accenture 2005userType All Rights = Reserved 24 ActionMapping    An ActionMapping object describes an Action instance to the ActionServlet. It represents the information that uniquely defines an instance of a particular action class. Provides useful information to both the Action.execute() and the ActionForm.validate() methods, enabling a developer to alter its behavior based upon the values describing this particular Action. ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved 25 Configuring Applications Struts Configuration File   Use configuration elements in developing Struts Application. These "static" configuration elements are: – – – <message-resources> ©2005 Accenture – © Accenture 2005 All Rights Reserved – All Rights Reserved. 26 Configuring Applications HRS struts-config.xml file <struts-config> <set-property property="autoCommit" value="false"/> <set-property property="description" value="Example Data Source Configuration"/> <set-property property="driverClass" value="org.postgresql.Driver"/> <set-property property="maxCount" value="4"/> <set-property property="minCount" value="2"/> ©2005 Accenture All Rights Reserved. 27 <set-property property="password" value="mypassword"/> © Accenture 2005 All Rights Reserved Configuring Applications HRS struts-config.xml file (cont.) …. ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved 28 Configuring Applications HRS struts-config.xml file (cont.) ©2005 Accenture All Rights Reserved. © Accenture 2005 Allname="approver" Rights Reserved 29 Configuring Applications HRS struts-config.xml file (cont.) Configuring Applications HRS struts-config.xml file (cont.) <set-property property="inputForward" value="true"/> <message-resources parameter="com.jds.architecture.util.messages"/> ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved 31 Resources      http://java.sun.com/webservices/docs/1.0/tutorial/d http://struts.apache.org/userGuide/building_model. http://struts.apache.org/userGuide/building_view.h http://struts.apache.org/userGuide/building_control http://struts.apache.org/userGuide/building_contro http://jakarta.apache.org/struts/ ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved 32 Questions & Comments . ©2005 Accenture All Rights Reserved. © Accenture 2005 All Rights Reserved 33 Related Documents Struts June 2020 26 Struts November 2019 49 Struts May 2020 36 Struts November 2019 50 Struts November 2019 46 Struts June 2020 5 More Documents from "" Threads May 2020 26 Ats Application Programming: Java Programming May 2020 40 Jsp May 2020 21 Servlet May 2020 21 Ajax May 2020 36 Wml May 2020 18 Copyright © 2024 PDFCOKE.