Struts2 with I18N. Zero Configuration. By convention By annotation. Struts2 with Tiles2. Hibernate with Struts2. Spring with Struts2. DateTimePicker Iterator Tag. Quiz Struts2 Misc. Quiz-1 Struts2 Misc.
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Struts 2 Java Web Development (3 days hands-on)
Actions are now POJOs which increases testability and reduces coupling in the framework, and HTML form field data is converted to proper types for the action to use. Still further decreasing coupling is request processing has been made more modular by allowing a series of interceptors custom or Struts2 provided to provide pre-processing and post-processing functionality. Modularity is a common theme a plug-in mechanism provides a way to augment the framework; key classes with the framework can be replaced with custom implementations to provide advanced features not provided out of the box; tags can utilize a variety of different rendering themes including custom themes ; and there are many different result types available for performing after-action execution tasks which include, but are not limited to, rendering JSPs, Velocity and Freemarker templates.
Struts 2 is a second-generation web application framework that implements the Model-View-Controller MVC design pattern.
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Unlike Struts 1, Struts 2 introduces several new architectural features that make the framework cleaner and more flexible. These new features include interceptors for layering cross-cutting concerns away from action logic; annotation-based configuration to reduce or eliminate XML configuration; a powerful expression language, Object-Graph Navigation Language OGNL , that transverses the entire framework; and a mini-MVC based tag API that supports modifiable and reusable UI components. The MVC pattern is a way of taking an application and breaking it into three distinct parts:. In Struts 2 the model, view and controller are implemented by the action, result and FilterDispatcher respectively.
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The MVC pattern has three key components:. Not only do patterns provide clean, proven designs, they also help the developers learning curve. Once you are familiar with the pattern, it is easy to apply its concepts to various projects. The Model-View-Controller design pattern is a time-proven architecture for building software that manages interaction with users using Views , implements business rules that are dependent on user input using Controllers , and relies on data that exists in a remote database or system accessed using Model components.
The advantage of using the MVC pattern is that there is no business or Model-specific processing within the presentation, or view, component itself. The opposite is also true; that is, there is no presentation logic in the model and business layers. The source distribution is for advanced users to suit the specific need e. We stick with the binary distribution. Download the latest binary release from here. The goal of this section is to give you a general understanding of different parts of Struts framework and show how they work together to form a complete program.
To accomplish that goal, we will develop a simple application that highlights each Struts component. Once you understand how this simple Struts application works, you will be able to easily understand other Struts programs because all share a common architecture. The example that we will use is a common part of web applications, checking user login. It has three web pages, login. The login page prompt the user to input name and password. If the user input the correct password, they will see a welcome page saying: Welcome 'Name of the user'. If the wrong password is input it will take the user to the error.
The goal of this section is to give you an overview of how to configure a struts application. Struts 2 configures applications in 2 ways:. The struts element is the mandatory document root of all Struts 2 XML files and the package element is an important container element for organizing your actions, results, and other component elements.
The mapping process is simple. The URL combines the servlet context with the package namespace and the action name. Note that the action name takes the. Use empty action components to forward to your results, even if they are simple JSPs that require no dynamic processing. This keeps the applications architecture consistent, prewires your workflow in anticipation of increases in complexity, and hides the real structure of your resources behind the logical namespace of the Struts 2 actions.
While we could technically use a URL that hits the form JSP directly, a well-accepted best practice is to route these requests through actions regardless of their lack of actual processing.
As you can see, such pass-through actions do not specify an implementation class. Include modularizes XML docs and are used to reduce congestion in the xml document in case of big applications. ActionSupport provides default implementations of the Action interface and several other useful interfaces, giving us such things as data validation and localization of error messages. It provides default implementations of several important interfaces. If your actions extend this class, they automatically gain the use of these implementations.
Any object can informally honor the contract with the framework by simply implementing an execute method that returns a control string. The Action interface also provides some useful String constants that can be used as return values for selecting the appropriate result.
The constants defined by the Action interface are:. These constants can conveniently be used as the control string values returned by your execute method. The most important elements in this deployment descriptor are the filter and filter-mapping elements that set up the Struts 2 Filter-Dispatcher. This filter will examine all the incoming requests looking for requests that target Struts 2 actions.
This means the filter will inspect all requests. The other important thing about the configuration of the Filter-Dispatcher is the initialization parameter that we pass in. It tells the framework which packages to scan for annotations. The controller's job is to map requests to actions. In a web application, the incoming HTTP requests can be thought of as commands that the user issues to the application. One of the fundamental tasks of a web application is routing these requests to the appropriate set of actions that should be taken within the application itself.
The role of the controller is played by the Struts 2 FilterDispatcher. This important object is a servlet filter that inspects each incoming request to determine which Struts 2 action should handle the request. The framework handles all of the controller work for you.
You just need to inform the framework which request URLs map to which of your actions. You can do this with XML-based configuration files or Java annotations. The model is the internal state of the application. This state is composed of both the data model and the business logic. From the high-level black box view, the data and the business logic merge together into the monolithic state of the application. For instance, if you are logging in to an application, both business logic and data from the database will be involved in the authentication process.
Most likely, the business logic will provide an authentication method that will take the username and password and verify them against some persisted data from the database. In this case, the data and the business logic combine to form one of two states, "authenticated" or "unauthenticated. A Struts 2 action serves two roles. First, an action is an encapsulation of the calls to business logic into a single unit of work. Second, the action serves as a locus of data transfer.
The controller, after receiving the request, must consult its mappings and determine which of these actions should handle the request. Once it finds the appropriate action, the controller hands over control of the request processing to the action by invoking it. This invocation process, conducted by the framework, will both prepare the necessary data and execute the action's business logic.
When the action completes its work, it'll be time to render a view back to the user who submitted the request. Toward this end, an action, upon completing its work, will forward the result to the Struts 2 view component. Basically the View layer is the conduit for getting data in and out of the application. It does not contain business logic.