difference between Struts 1.x and Struts 2.x

Question

i want to know difference between Struts 1.x and Struts 2.x

Answer 1

It's a totally different web framework... Struts2 is basically the old Webwork.

Some differences:

• Struts2 works with POJOs, no more ActionForms. All attributes from the requests are populated in "standard" Java classes.
• Struts2 actions are not coupled with the Servlet API, they do not receive HttpServletRequest and HttpServletResponse as parameters. Also, they are stateful, (Struts 1 actions were stateless).
• Struts2 have a lot of enhancements like the Interceptor API, plus lots of integrations.
• Configuration is totally different.

I recommend you to "retire" Struts1 in favor of modern web frameworks.

Answer 2

Feature Struts 1 Struts 2
Action classes Struts1 extends the abstract base class by its action class. The problem with struts1 is that it uses the abstract classes rather than interfaces. While in Struts 2, an Action class implements an Action interface, along with other interfaces use optional and custom services. Struts 2 provides a base ActionSupport class that implements commonly used interfaces. Although an Action interface is not necessary, any POJO object along with an execute signature can be used as an Struts 2 Action object.
Threading Model Struts 1 Actions are singletons therefore they must be thread-safe because only one instance of a class handles all the requests for that Action. The singleton strategy restricts to Struts 1 Actions and requires extra care to make the action resources thread safe or synchronized while developing an application. Struts 2 doesn't have thread-safety issues as Action objects are instantiated for each request. A servlet container generates many throw-away objects per request, and one more object does not impose a performance penalty or impact garbage collection.
Servlet Dependency Actions are dependent on the servlet API because HttpServletRequest and HttpServletResponse is passed to the execute method when an Action is invoked therefore Struts1. Container does not treat the Struts 2 Actions as a couple. Servlet contexts are typically represented as simple Maps that allow Actions to be tested in isolation. Struts 2 Actions can still access the original request and response, if required. While other architectural elements directly reduce or eliminate the need to access the HttpServetRequest or HttpServletResponse.
Testability Struts1 application has a major problem while testing the application because the execute method exposes the Servlet API. Struts TestCase provides a set of mock object for Struts 1. To test the Struts 2 Actions instantiate the Action, set the properties, and invoking methods. Dependency Injection also makes testing easier.
Harvesting Input Struts 1 recieves an input by creating an ActionForm object. Like the action classes, all ActionForms class must extend a ActionForm base class. Other JavaBeans classes cannot be used as ActionForms, while developers create redundant classes to receive the input. DynaBeans is the best alternative to create the conventional ActionForm classes. Struts 2 requires Action properties as input properties that eliminates the need of a second input object. These Input properties may be rich object types, since they may have their own properties. Developer can access the Action properties from the web page using the taglibs. Struts 2 also supports the ActionForm pattern, POJO form objects and POJO Actions as well.
Expression Language Struts1 integrates with JSTL, so it uses the JSTL EL. The EL has basic object graph traversal, but relatively weak collection and indexed property support. Struts 2 can use JSTL, but the framework also supports a more powerful and flexible expression language called "Object Graph Notation Language" (OGNL).
Binding values into views Struts 1 binds objects into the page context by using the standard JSP mechanism. Struts 2 uses a ValueStack technology to make the values accessible to the taglibs without coupling the view to the object to which it is rendering. The ValueStack strategy enables us to reuse views across a range of types, having same property name but different property types.
Type Conversion Struts 1 ActionForm properties are almost in the form of Strings. Commons-Beanutils are used by used by Struts 1 for type conversion. Converters are per-class, which are not configurable per instance. Struts 2 uses OGNL for type conversion and converters to convert Basic and common object types and primitives as well.
Validation Struts 1 uses manual validation that is done via a validate method on the ActionForm, or by using an extension to the Commons Validator. Classes can have different validation contexts for the same class, while chaining to validations on sub-objects is not allowed. Struts 2 allows manual validation that is done by using the validate method and the XWork Validation framework. The Xwork Validation Framework allows chaining of validations into sub-properties using the validations defined for the properties class type and the validation context.
Control Of Action Execution Each module in Struts 1 has a separate Request Processors (lifecycles), while all the Actions in the module must share the same lifecycle. In Struts 2 different lifecycles are created on a per Action basis via Interceptor Stacks. Custom stacks are created and used with different Actions, as

Answer 3

The major difference is that in Struts1.x the request directly goes to the servlet, whereas in Struts2.x the request and response traval though the stack of interceptor or filter. The regular logic can be placed in Filter classes and developer can concentrate on the Business Logic. Besides this there is also differences in directory structure.

It is better to know the differences between Struts1.x and Struts2.x topic wise. Here's a cite of http://www.geekinterview.com/question_details/64360:

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1. Action Classes

In Struts 1.x the action classes should extend Action (or DispatchAction) class and the execute method have number of parameter and a ActionForward return type , but In struts 2.x the action class can also be simple pojo having execute method returning only a string without any input parameter.

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2. Servlet Dependancy

Container does not treat Struts2.x, unlike that of Struts1.x, Actions as a request / response couple and struts2.x action can still access the original request and response.

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3. Getting Input

• In Struts1.x form beans are used to define properties, getters & setters, in struts2.x getters/setters are defined in action classes itself.
• Struts1.x form beans class must extend ActionForm or ValidatorForm, but Struts2.x beans can also be POJO.

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4. Testability

• In Struts1.x execute() method exposes the servlet API for testing.
• Struts2.x Dependancy Injection be used to simplify the testing process.

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5. Expression Languages

• Struts1.x JSTL as its expression language, where as Struts2.x uses OGNL(Object Graphic Notation Language) as its expression language which is very strong than JSTL.
• Struts2.x can also use JSTL.

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6. Type Conversion

• In Struts1.x properties are almost in String form, Convertors are per class which are not configurable.
• Struts 2.x uses OGNL for type conversion

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7. Validation

Server side validation are made in action classes in Struts2.x, a much simpler way.