Because UserNumberBean is session-scoped, have it implement the Serializable interface. Use the hint badge to import java. Serializable into the class. To facilitate this, add userNumber and response properties to the class.
Choose Getter and Setter. Create a response property. Declare a String named response. Create a getter method for response. This application will not require a setter. For purposes of this tutorial however, just paste the below method into the class. The above method performs two functions: 1. It tests whether the user-entered number userNumber equals the random number generated for the session randomInt and returns a String response accordingly. It invalidates the user session if the user guesses the right number i.
This is necessary so that a new number is generated should the user want to play again. Import statements are automatically created for:. You can press Ctrl-Space on items in the editor to invoke code-completion suggestions and documentation support. Click the web browser icon in the documentation window to open the Javadoc in an external web browser. You saw an example of this in the previous section, where JSF instantiated a UserNumberBean object when you ran the application.
This notion is referred to as Inversion of Control IoC , which enables the container to take responsibility for managing portions of the application that would otherwise require the developer to write repetitious code. In the previous section you created a managed bean that generates a random number between 0 and You also created two properties, userNumber , and response , which represent the number input by the user, and the response to a user guess, respectively.
In this section, you explore how you can use the UserNumberBean and its properties in web pages. JSF enables you to do this using its expression language EL. This section also demonstrates how you can take advantage of JSF 2. The IDE provides support for this work through its code completion and documentation facilities, which you can invoke by pressing Ctrl-Space on items in the editor. Start by making changes to index. Open the index. Either double-click the index.
Simply uncomment them and comment out the HTML elements currently being used. Comment out the HTML form element. You can also apply this keyboard shortcut to other file types, such as Java and CSS. Place your cursor on any of the undeclared tags and press Alt-Enter and click Enter to add the suggested tag library. If there are multiple options, make sure to select the tag that is displayed in the editor before clicking Enter.
The value attribute can be used to specify the current value of the rendered component. Type in the code displayed in bold below. Within these delimiters, you specify the name of the managed bean and the bean property you want to apply, separated by a dot. Also, when the page is requested and a value for userNumber has already been set, the value will automatically display in the rendered inputText component.
For more information, see the Java EE 7 Tutorial: Specify the destination for the request that is invoked when clicking the form button. Furthermore, due to JSF 2. The JSF runtime searches for a file named response. If you were using JSF 1. Steps 7 through 12 below are optional. Test whether the above EL expression does in fact call the setUserNumber method when the request is processed. Set a breakpoint on the setUserNumber method signature.
You can do this by clicking in the left margin. A red badge displays, indicating a method breakpoint has been set. A debug session starts, and the project welcome page opens in the browser. The debugger is suspended within the setUserNumber method. You see the variable values for the point at which the debugger is suspended. The number 4 was entered into the form. Beneath it, you see that the value for the userNumber property is currently null. In the Debugger toolbar, click the Step Into button.
The debugger executes the line on which it is currently suspended. The Variables window refreshes, indicating changes from the execution. Open the response. Either double-click the response. Place your cursor on any of the undeclared tags and press Ctrl-Space. Code completion suggestions and documentation support displays. Click Enter. Specify the destination for the request that is invoked when the user clicks the form button.
You want to set the button so that when a user clicks it, he or she is returned to the index page. Type in the code displayed in bold. When a user clicks the form button, the JSF runtime searches for a file named index. It assumes the file extension is the same as the extension used by file from which the request originated response. To do this, use the JSF expression language. Enter the following in bold.
When the welcome page displays in the browser, enter a number and click submit. You see the response page display similar to the following provided you did not guess the correct number.
The Back button is not displaying in the correct location. Compare it to the original version. Place your cursor between outputText and value , insert a space, then press Ctrl-Space to invoke code-completion. Scroll down to choose the escape attribute and inspect the documentation. As indicated by the documentation, the escape value is set to true by default. This means that any characters that would normally be parsed as html are included in the string, as shown above.
Setting the value to false enables any characters that can be parsed as html to be rendered as such. Interview Questions. Company Questions. Artificial Intelligence. Cloud Computing. Data Science. Angular 7. Machine Learning. Data Structures. Operating System. Computer Network. Compiler Design.
Computer Organization. Discrete Mathematics. Ethical Hacking. Computer Graphics. Software Engineering. Web Technology. Cyber Security. Eventually, you'll want to explore other ways a JSF component can interact with the Java backend--things like data lists and grids and a variety of input controls. These are deployed as.
The structure of a. One of Java's strengths is that it is standards based, and those standards are governed by an open source community process. Once a specification or specification improvement has been developed and approved by JCP, it is available to be implemented by multiple parties. Each of these frameworks implements the JSF core, which includes some standard components. Vendors may also offer additional component libraries on top of the standard.
When evaluating JSF frameworks, it's a good idea to consider the needs of your application and what component libraries are available to help you build it.
Ideally, your JSF framework should get you as close as possible to what you need, right out of the box. In the MVC pattern, the idea is to separate the three concerns of a UI into discreet parts, so they're easier to manage. In general, the view is responsible for displaying data in the model, and the controller is responsible for setting up the model and routing the user to the correct view.
These define the layout of the user interface. In JSF 2. This listing assumes the application has the cdi-api This will pull up the DataList demo code for PrimeFaces. Figure 2 shows the output of a simple data table, which is taken from the PrimeFaces DataList demo. Listing 3 presents the markup for this dataList display. If you scroll to the bottom of the PrimeFaces showcase, you can see the markup in the dataList. In Listing 3, notice the value property of the dataList component.
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