What are the key features of Struts 2x ?

Simplified Design

• Programming the abstract classes instead of interfaces is one of design problem of struts1x framework that has been resolved in the struts 2 framework. 
• Most of the Struts 2 classes are based on interfaces  
• Most of its core interfaces are HTTP independent 
• Struts 2 Action classes are framework independent and are simplified to look as simple POJOs. 
• Framework components are tried to keep loosely coupled.

Simplified Actions

• Actions are simple POJOs.
• Any java class with execute() method can be used as an Action class.
• Even we don't need to implement interfaces always.
• Inversion of Control is introduced while developing the action classes.
• makes the actions to be neutral to the underlying framework

No more ActionForms

• ActionForm feature is no more known to the struts2 framework.
• Simple JavaBean flavored actions are used to put properties directly.
• No need to use all String properties.

Simplified testability

• Struts 2 Actions are HTTP independent and framework neutral.
• This enables to test struts applications very easily without resorting to mock objects.

Intelligent Defaults

• Most configuration elements have a default value which can be set according to the need.
• Even there are XML-based default configuration files that can be overridden according to the need.

Improved results

• Unlike ActionForwards, Struts 2 Results provide flexibility to create multiple type of outputs and in actual it helps to prepare the response.

Better Tag features

• Struts 2 tags enables to add style sheet-driven markup capabilities, so that we can create consistent pages with less code.
• Struts 2 tag markup can be altered by changing an underlying stylesheet.
• Individual tag markup can be changed by editing a FreeMarker template.
• Struts 2 tags are more capable and result oriented.
• Both JSP and FreeMarker tags are fully supported.

Annotations introduced

• Applications in struts 2 can use Java 5 annotations as an alternative to XML and Java properties configuration.
• Annotations minimize the use of XML.

Stateful Checkboxes

• Struts 2 checkboxes do not require special handling for false values.

QuickStart

• Many changes can be made on the fly without restarting a web container.

Customizing controller

• Struts 1 lets to customize the request processor per module, Struts 2 lets to customize the request handling per action, if desired.

Easy Spring integration

• Struts 2 Actions are Spring-aware. Just need to add Spring beans.

Easy plugins

• Struts 2 extensions can be added by dropping-in a JAR.
• No manual configuration is required.

AJAX support

• The AJAX theme gives interactive applications a significant boost.
• The framework provides a set of tags to help you ajaxify your applications, even on Dojo.
• The AJAX features include :
• AJAX Client Side Validation
• Remote form submission support (works with the submit tag as well)
• An advanced div template that provides dynamic reloading of partial HTML
• An advanced template that provides the ability to load and evaluate JavaScript remotely.
• An AJAX-only tabbed Panel implementation
• A rich pub-sub event model Interactive auto complete tag