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Apache Struts 2. It is available in a full distribution, or as separate library, source, example and documentation distributions. Struts 2. This servlet reads a configuration file; the name of this configuration file is specified as the config parameter in web.
The web. This is a fairly typical web. It configures a single servlet, the Struts ActionServlet , and specifies the location of struts-layout. It also sets the name of the Struts configuration file, struts-config.
This file controls which Struts actions the Struts application will use. The last piece of configuration in web. Later, you'll see how struts-config. Then the servlet gets any information it needs through a call to the request object usually via request. Struts introduces the concept of an action form to make a cleaner interface between the client and the server, avoiding all the request. An action form is a Struts class that encapsulates the parameters passed from the client to the server.
The form you use in your application extends the org. ActionForm class, and each parameter that you post to the server is represented in the action form. An action form is a Java bean that stores data for the view. Basically, that means that the form has private properties and public getter and setter methods for each property. The data in the form is set by actions that are invoked before the JSP uses it. The JSP typically populates itself by calling tag libraries with the property field set to the field name of the form.
Look at results. So, instead of calling request. The form is passed into the ActionServlet , so all you have to do is cast it to the UserForm class. Example presents the UserForm that stores the data for the view, with its getters and setters: it's a plain old Java bean with accessor methods for username , firstName , and lastName.
The familiar Java servlet is now represented by a Struts action. When writing Struts applications, instead of writing servlets, you write actions. Think of servlets as having been deprecated in favor of the Struts Action class. The UserAction class extends the Struts Action class, and instead of putting redirection code in the servlet, the program flow is controlled by struts-config.
The Struts action connects the business logic to the view. Example shows the code for the UserAction. Notice how the execute method gets the UserForm , reads the username from the UserForm , calls a private method to gather information from the database, and then sets other values in the UserForm to be passed on to the next part of the application.
The next part of the application is accessed by the call to mapping. That tile is defined as results. Now, on to the struts-config. Struts is an implementation of an MVC framework, where the model the application data is represented by your own objects typically Java beans , the view is implemented by JSPs, and the actions, as configured by struts-config. The Struts Form objects carry information between the View s and the Action s.
UserForm the Struts form that we developed earlier. When a user is selected from the suggestion field in usermanager. Next, control passes to results. You can mix HTML tags with the layout: tags to give you more control over the page's appearance, but don't forget about the CSS file if you want more control over the look of the page. The results JSP. The data behind this application comes from the MySQL database that we have been using throughout this book.
It also uses the DatabaseConnector class from Chapter 5 see Example Connection; import java. Apache Struts 2 source code and documentation is licensed to the Apache Software Foundation ASF under one or more contributor license agreements.
See the License for the specific language governing permissions and limitations under the License. Version notes. S , S S , S , S , S , S ,.
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