Difference between struts1.2 and struts2.0?

Answer Posted / sunil kumar suman

1. Servlet Dependency:

Actions in Struts1 have dependencies on the servlet API
since the HttpServletRequest and HttpServletResponse
objects are passed to the execute method when an Action is
invoked but in case of Struts 2, Actions are not container
dependent because they are made simple POJOs. In struts 2,
the servlet contexts are represented as simple Maps which
allows actions to be tested in isolation. Struts 2 Actions
can access the original request and response, if required.
However, other architectural elements reduce or eliminate
the need to access the HttpServetRequest or
HttpServletResponse directly.

2. Action classes

Programming the abstract classes instead of interfaces is
one of design issues of struts1 framework that has been
resolved in the struts 2 framework.
Struts1 Action classes needs to extend framework dependent
abstract base class. But in case of Struts 2 Action class
may or may not implement interfaces to enable optional and
custom services. In case of Struts 2 , Actions are not
container dependent because they are made simple POJOs.
Struts 2 provides a base ActionSupport class to implement
commonly used interfaces. Albeit, the Action interface is
not required. Any POJO object with an execute signature can
be used as an Struts 2 Action object.

3. Validation

Struts1 and Struts 2 both supports the manual validation
via a validate method.
Struts1 uses validate method on the ActionForm, or
validates through an extension to the Commons Validator.
However, Struts 2 supports manual validation via the
validate method and the XWork Validation framework. The
Xwork Validation Framework supports chaining validation
into sub-properties using the validations defined for the
properties class type and the validation context.

4. Threading Model

In Struts1, Action resources must be thread-safe or
synchronized. So Actions are singletons and thread-safe,
there should only be one instance of a class to handle all
requests for that Action. The singleton strategy places
restrictions on what can be done with Struts1 Actions and
requires extra care to develop. However in case of Struts
2, Action objects are instantiated for each request, so
there are no thread-safety issues. (In practice, servlet
containers generate many throw-away objects per request,
and one more object does not impose a performance penalty
or impact garbage collection.)

5. Testability

Testing Struts1 applications are a bit complex. A major
hurdle to test Struts1 Actions is that the execute method
because it exposes the Servlet API. A third-party
extension, Struts TestCase, offers a set of mock object for
Struts1. But the Struts 2 Actions can be tested by
instantiating the Action, setting properties and invoking
methods. Dependency Injection support also makes testing
simpler. Actions in struts2 are simple POJOs and are
framework independent, hence testability is quite easy in
struts2.

6. Harvesting Input

Struts1 uses an ActionForm object to capture input. And all
ActionForms needs to extend a framework dependent base
class. JavaBeans cannot be used as ActionForms, so the
developers have to create redundant classes to capture
input.
However Struts 2 uses Action properties (as input
properties independent of underlying framework) that
eliminates the need for a second input object, hence
reduces redundancy. Additionally in struts2, Action
properties can be accessed from the web page via the
taglibs. Struts 2 also supports the ActionForm pattern, as
well as POJO form objects and POJO Actions. Even rich
object types, including business or domain objects, can be
used as input/output objects.

7. Expression Language

Struts1 integrates with JSTL, so it uses the JSTL-EL. The
struts1 EL has basic object graph traversal, but relatively
weak collection and indexed property support. Struts 2 can
also use JSTL, however it supports a more powerful and
flexible expression language called "Object Graph Notation
Language" (OGNL).

8. Binding values into views

In the view section, Struts1 uses the standard JSP
mechanism to bind objects (processed from the model
section) into the page context to access. However Struts 2
uses a "ValueStack" technology so that the taglibs can
access values without coupling your view to the object type
it is rendering. The ValueStack strategy allows the reuse
of views across a range of types which may have the same
property name but different property types.

9. Type Conversion

Usually, Struts1 ActionForm properties are all Strings.
Struts1 uses Commons-Beanutils for type conversion. These
type converters are per-class and not configurable per
instance. However Struts 2 uses OGNL for type conversion.
The framework includes converters for basic and common
object types and primitives.

10. Control Of Action Execution

Struts1 supports separate Request Processor (lifecycles)
for each module, but all the Actions in a module must share
the same lifecycle. However Struts 2 supports creating
different lifecycles on a per Action basis via Interceptor
Stacks. Custom stacks can be created and used with
different Actions as needed.

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