Struts 2 Overview

Struts2 is popular and mature web application framework based on the MVC design pattern. Struts2 is not just the next version of Struts 1, but it is a complete rewrite of the Struts architecture.

Struts 2 - Environment Setup

Our first task is to get a minimal Struts 2 application running. This chapter will guide you on how to prepare a development environment to start your work with Struts 2. I assume that you already have have JDK (5+), Tomcat and Eclipse installed on your machine.

Struts 2 - Architecture

From a high level, Struts2 is a pull-MVC (or MVC2) framework. The Model-View-Controller pattern in Struts2 is realized with following five core components:

Struts 2 - Hello World Example

As you learnt from the Struts 2 architecture, when you click on a hyperlink or submit an HTML form in a Struts 2 web application, the input is collected by the Controller which is sent to a Java class called Actions. After the Action is executed, a Result selects a resource to render the response.

Struts 2 - Configuration Files

This chapter will take you through basic configuration required for a Struts 2 application. Here we will see what will be configured in few important configuration files : web.xml, struts.xml, struts-config.xml and struts.properties

Struts 2 - Actions

Actions are the core of the Struts2 framework, as they are for any MVC (Model View Controller) framework. Each URL is mapped to a specific action, which provides the processing logic necessary to service the request from the user.

Struts 2 - Interceptors

Interceptors are conceptually the same as servlet filters or the JDKs Proxy class. Interceptors allow for crosscutting functionality to be implemented separately from the action as well as the framework. You can achieve the following using interceptors:

Struts 2 - Results & Result Types

As mentioned previously, the <results> tag plays the role of a view in the Struts2 MVC framework. The action is responsible for executing the business logic. The next step after executing the business logic is to display the view using the <results> tag.

Struts 2 - Value Stack/OGNL

The Value Stack

The value stack is a set of several objects which keeps the following objects in the provided order:

SN	Objects & Description
1	Temporary Objects There are various temporary objects which are created during execution of a page. For example the current iteration value for a collection being looped over in a JSP tag.

Struts 2 - File Uploads

The Struts 2 framework provides built-in support for processing file uploads using "Form-based File Upload in HTML". When a file is uploaded it will typically be stored in a temporary directory and they should be processed or moved by your Action class to a permanent directory to ensure the data is not lost.

Struts 2 - Database Access

This chapter will teah you how to access a database using Struts 2 in simple steps. Struts is a MVC framework and not a database framework but it provides excellent support for JPA/Hibernate integration. We shall look at the hibernate integration in a later chapter, but in this chapter we shall use plain old JDBC to access the database.

Struts 2 - Sending Email

This chapter will teach you how you can send an email using your Struts 2 application. For this exercise, you need to download and install the mail.jar from JavaMail API 1.4.4 and place the mail.jar file in your WEB-INF\lib folder and then proceed to follow the standard steps of creating action, view and configuration files.

Struts 2 - Validations Framework

Now we will look into how Struts's validation framework. At Struts's core, we have the validation framework that assists the application to run the rules to perform validation before the action method is executed.

Localization, internationalization (i18n)

Internationalization (i18n) is the process of planning and implementing products and services so that they can easily be adapted to specific local languages and cultures, a process called localization. The internationalization process is sometimes called translation or localization enablement.

Struts 2 - Type Conversion

Everything on a HTTP request is treated as a String by the protocol. This includes numbers, booleans, integers, dates, decimals and everything else. Every thing is a string according to HTTP.

Struts2 - Themes & Templates

Before starting actual tutorial for this chapter, let us look into few definition as given by http://struts.apache.org:

Struts 2 - Exception Handling

Struts provides an easier way to handle uncaught exception and redirect users to a dedicated error page. You can easily configure Struts to have different error pages for different execeptions.

Struts 2 - Annotations

As mentioned previously, Struts provides two forms of configuration. The traditional way is to use the struts.xml file for all the configurations. We have seen so many examples of that in the tutorail so far.

Struts 2 - Control Tags

The Struts 2 tags have a set of tags that make it easy to control the flow of page execution. Following is the list of important Struts 2 Control Tags:

Struts 2 - Data Tags

The Struts 2 data tags are primarily used to manipulate the data displayed on a page. Listed below are the important data tags: