web development with apache struts 2

Nov 20, 2008 Web Development with Apache Struts 2 1

Web Development withApache Struts 2

Fabrizio Giudici

Tidalwave sas, CEONetBeans Dream Team

Senior Java Architect, Blogger

www.tidalwave.itbluemarine.tidalwave.itweblogs.java.net/blog/fabriziogiudicistoppingdown.net


Agenda

● Java Web Frameworks● Struts basics● Struts 2● A small code example● Q&A


NetBeans 6.5 is out

● Get it while it's hot! www.netbeans.org– Faster!

– Compile-on-save, multithreading Java debugger, visual deadlock indication

– PHP support, JavaScript debugger and library manager, better Spring / Hibernate / JSF / JPA support

– RESTful web services, SQL editor improvements, JavaFX, Groovy and Grails, Ruby and Rails improvements, GlassFish v3

●


Java Web Frameworks

● Question: how many Java web frameworks are available?

– 1?

– 5?

– 10?

– Dozens?


Java Web Frameworks

● Answer: more than 50!– www.manageability.org/blog/stuff/how-

many-java-web-frameworks

● Of course, those with a significant spread are not so many

● But choosing is difficult● NIH, but also radically different

approaches


My (subjective) take● Wicket

– You really want to be agile

– You routinely live on the leading edge

● Tapestry– You like agile, but consolidated

● Struts– You are “conservative” and like it easy

● Java Server Faces– You love visual designers

– You can survive to high complexity


JEE

● JEE Web components:– “Foundation”: Servlet, JSP, Filter

– “High level”: JSF

● Foundation elements are enough, but you're going to write tons of code

– Validation, flow control, etc...


Struts

● Struts 1 appeared in June 2001– Apache License

– Strictly based on MVC pattern

– Supported declarative validation, flow control

● Struts 2 is the “merge” of Struts 1 + WebWork


MVC


Struts 2.x benefits

● Actions are POJOs● Interceptors (from AOP)● Classes are now independent of HTTP● Simplified testing● Annotations, AJAX, Spring, Portlets,

etc...


Workflow


Components

● web.xml

– Installs a Filter on /*

● struts.xml

– Maps Action names

– Defines the navigation flow

● Actions– Execute a task

● Views (JSP or others)– Render the UI


web.xml

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

...

</web-app>


A simple Action

import com.opensymphony.xwork2.ActionSupport;

public class MyAction extends ActionSupport { private final List<String> NBDTers = Arrays.asList(...);

private String userName; private String message;

public String getUserName() { return userName; }

public void setUserName(String userName) { this.userName = userName; }

public String getMessage() { return message; }

@Override public String execute() { message = userName; return NBDTers.contains(userName) ? "nbdt" : SUCCESS; }}


struts.xml

<struts>

<package name="/" extends="struts-default"><action name="MyAction" class="myexample.MyAction">

<result name="input">/index.jsp</result><result name="success">/good.jsp</result><result name="nbdt">/nbdt.jsp</result>

</action></package>

</struts>


A simple view JSP

<%@page contentType="text/html" pageEncoding="UTF-8"%><%@taglib prefix="s" uri="/struts-tags" %>

<html> <body> <h2>Welcome to JUG Lugano</h2> Hello, <s:property value="message" default="Guest" />, welcome to the first meeting of JUG Lugano! <s:form method="GET" action="MyAction.action"> Would you be so kind to tell me your name? <s:textfield name="userName" /> <s:submit value="Submit" /> </s:form>

<s:actionerror/> <s:fielderror/> </body></html>


Interceptors

● Used to implement “common” behaviours

– Validations

– Multiple submit filters

– Logging

● Pre-defined interceptors


Formal validation

● Declarative, save tons of code

<validators> <field name="userName"> <field-validator type="requiredstring"> <param name="trim">true</param> <message>Your name is required.</message> </field-validator> </field>

</validators>


Interceptors

● Code that is invoked across Actions● Many pre-defined interceptors

– Parameter rename, cookie management, component behaviours (e.g. Checkboxes), background actions

– Validation itself is an interceptor


Custom interceptors

public interface Interceptor extends Serializable { public void destroy();

public void init();

public String intercept (ActionInvocation inv) throws Exception; }


Interceptors in struts.xml

<struts>

<package name="/" extends="struts-default"> <interceptors> <interceptor name="logger" class="..."/> </interceptors>

<action name="MyAction" class="myexample.MyAction"> <interceptor-ref name="logger"/>

<result name="success">/good.jsp</result><result name="nbdt">/nbdt.jsp</result><result name="input">/index.jsp</result>

</action></package>

</struts>


Conclusion

● Robust, Struts 1 heritage● Keeps up with the latest standards

(POJOs, AOP, annotations, Spring, ...)● “Conservative” approach, but easy● Relevant sites:

– struts.apache.org

– beans.seartipy.com/2008/08/04/struts-2-plugin-for-netbeans-ide-nbstruts2support/

web development with apache struts 2

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