Question

(Page Hit Counter with ApplicationBean) Create a JSP that uses the ApplicationBean to keep track of how many times a page has been visited. [Note: if you were to deploy this page on the web, it would count the number of times that any computer requested the page, unlike in the previous exercise.] Display the number of page hits (i.e., the value of an int property in the ApplicationBean ) every time the page loads.

Short answer

Use an `ApplicationBean` for counting visits, increment the counter in JSP during each page load, and display the count.

Step-by-step solution

Creating the ApplicationBean

First, create an `ApplicationBean` class that holds an integer property to track page visits. The class will need a getter method to retrieve the current page hit count and a method to increment this count. Below is a basic implementation: ```java public class ApplicationBean { private int pageHits = 0; public int getPageHits() { return pageHits; } public void incrementPageHits() { pageHits++; } } ```

Configuring the JSP Page

Next, set up the JSP page to use the `ApplicationBean` to track the page visits. You should initialize the `ApplicationBean` in the application scope so that it's shared across all sessions and requests. Add the following lines to the JSP page: ```jsp <%@ page import="com.example.ApplicationBean" %> ```

Incrementing the Page Counter

Whenever the page is loaded, increment the property in the `ApplicationBean` to track this new visit. Utilize the following JSP code to call the increment method: ```jsp <% appBean.incrementPageHits(); %> ```

Displaying the Hit Counter

Finally, display the total number of page hits using the `ApplicationBean`. This can be achieved with the following JSP expression: ```jsp

This page has been visited <%= appBean.getPageHits() %> times.

```

Testing

Deploy the JSP on your web server. Visit the page multiple times from different devices or browsers to verify that the page hit count increments as expected and resets only when the web server is restarted.

Key concepts

ApplicationBean

An `ApplicationBean` is a Java class playing a critical role in JSP applications. It serves as a data container, primarily designed to hold and manage page-related information such as count of visits in this context. The `ApplicationBean` class is simple yet invaluable. Its key function is to maintain a property that records the number of times a page is visited by any user on any machine. To establish this, the class typically defines:

• An integer property that starts at zero, representing the number of page hits.
• A getter method like `getPageHits` to retrieve the current hit count.
• An increment method such as `incrementPageHits` that adds one to the hit count each time the page is loaded.

Incorporating an `ApplicationBean` ensures that your web application's components can effectively store and manipulate data over its lifecycle.

Page Hit Counter

A page hit counter is a mechanism integrated into web applications to record the number of times a web page is accessed. It offers significant insights into the page's popularity and engagement level across visitors. In a JSP application, the hit counter leverages the `ApplicationBean` to handle the counting logic. Every time the page is loaded, the hit counter increments. This persistent tracking allows the page hit count to be available each time any client views the page. Implementing the counter in a JSP involves refreshing a certain property in the `ApplicationBean`, thus maintaining an accurate count across different users. It showcases a fundamental dynamic capability of JSP to handle data applications effectively, giving feedback on user interactions directly via the webpage itself.

Increment Method

The increment method in an `ApplicationBean` is straightforward yet essential. Its main functionality is to increment, or increase, the current value of a property, often crucial in scenarios like hit counting where frequent updates occur. For this specific counter application, the method `incrementPageHits` is employed. Each time a request is made to load the page:

• This method is called to add one to the current page hits count.
• The execution ensures that the visit tally accurately reflects the number of accesses.

By invoking this method, the `ApplicationBean` seamlessly updates its stored data, which can then be displayed to users immediately. Such methods are fundamental to maintaining real-time interactions in web applications.

Application Scope

In JavaServer Pages, the concept of scope is paramount in determining how a particular object, like a bean, lives and behaves during an application's life cycle. Within this framework, the application scope plays a major role. Application scope implies that a particular object is shared between all requests and sessions. It's like a global space within the web application. By assigning the `ApplicationBean` to the application scope, you ensure:

• The same bean instance is used across all sessions.
• The page hit counter remains consistent and cumulative as different users navigate the page.
• Access and update to the bean are synchronized, avoiding potential conflicts.

This scope is ideal for maintaining states that should persist across the entire application’s duration, like visit counters, offering a robust and reliable tracking mechanism across user activities on the page.