Question

Modify the bookstore case study to cnable the client to change the quantity of an item currently in the shopping cart. In viewCart. jsp, display the quantity in an input element of type text in a form. Provide the user with a submit button with the value Update Cart that enables the user to submit the form to a servlet that updates the quantity of the items in the cart. The servlet should forward the request to viewCart. \(j\) sp, so the user can see the updated cart contents. Redeploy the bookstore application, and test the update capability.

Short answer

Modify `viewCart.jsp` to include a form with text inputs for quantities, create a servlet to process updates, and forward back to `viewCart.jsp`. Redeploy and test.

Step-by-step solution

Modify the Shopping Cart JSP

Navigate to the `viewCart.jsp` file in your project directory. Locate the section where the quantities of the cart items are displayed. Replace each quantity display with an `` element of type `text`. This will allow users to modify the quantity directly in their shopping cart. Ensure each `` has a unique identifier corresponding to the item's ID for backend processing.

Add Form and Submit Button

Wrap the cart items and input fields within a `

` element in the `viewCart.jsp`. At the bottom of the list, add a `` element with `type='submit'` and the label 'Update Cart'. Set the form's `action` attribute to point to the servlet URL that will handle the cart update functionality.

Implement the Update Cart Servlet

Create a new servlet (e.g., `UpdateCartServlet`) or extend an existing one to handle the form submission. In this servlet, retrieve the updated quantities from the request using the unique identifiers from the form. Update the item quantities in the shopping cart session object accordingly. Make sure to include appropriate error checking for invalid or empty quantities.

Forward to Updated Cart View

Once the quantities are updated in the session, use the `RequestDispatcher` to forward the request back to `viewCart.jsp`. This action will allow the user to see the updated quantities in their shopping cart.

Redeploy and Test the Application

Redeploy the bookstore application on your server. Access the updated `viewCart.jsp` through the application interface, change the quantities of some items, and click 'Update Cart'. Verify that all changes reflect the correct updated quantities in the shopping cart, ensuring no discrepancies.

Key concepts

JSP

JavaServer Pages (JSP) is an essential technology when it comes to web development in Java. It allows developers to create dynamically generated web pages based on HTML, XML, or other document types. JSP is built on top of Java Servlets, offering a more accessible way to manage dynamic content.
By using JSP, developers can embed Java code directly into HTML pages using special tags. This makes it easier to build interactive web applications like online stores or content management systems.
One significant advantage of JSP is its ability to separate the user interface from content generation. Developers can design pure HTML pages and include Java code only when necessary, promoting a clear division of roles within the development team. Furthermore, JSP supports tag libraries, which simplifies the creation of HTML elements for users, as seen in functionalities like updating shopping cart quantities.

shopping cart

In e-commerce applications, the shopping cart is a critical component which allows users to store and manage their selected items before proceeding to checkout. It reflects a virtual cart that you would push around a physical store.
In a web application, the shopping cart stores information such as the item details, quantity, and price. This data is often managed within the user's session, offering a seamless shopping experience.
For example, when modifying an item quantity in a shopping cart, like in the bookstore case study, the items' quantities can be dynamically updated using input fields and then processed by a servlet. These updates allow users to change their decisions about their purchases easily, enhancing the overall usability and flexibility of the application.

web development

Web development is a crucial aspect of creating applications and services over the internet. It involves various components such as client-side scripting, server-side programming, database management, and layout and design.
With technologies such as Java Servlets and JSP, developers can create robust and efficient server-side applications that manage data flow between users and databases. These technologies enable the handling of requests, processing input, and sending responses back to users.
A successful web development process means integrating these technologies effectively to build a cohesive application. For instance, in the exercise, setting up a servlet that adjusts item quantities in a shopping cart and then updates the cart view encompasses both server-side logic and user interface design, an essential web development practice.

Java programming

Java programming is widely used in building cross-platform applications, thanks to its "write once, run anywhere" philosophy. It's an object-oriented language that provides simplicity and power to developers.
In web development, Java is used on the server-side, where servlets and JSPs play major roles. Java programming enables building applications that are secure, robust, and scalable.
When working on e-commerce platforms, Java programming is applied to manage shopping carts or process complex transactions securely. With servlets handling requests and responses, and JSPs managing the display logic, Java ensures efficient processing of user actions.
For example, updating a shopping cart requires reading input, validating it, modifying session data, and displaying results. Each of these steps benefits from Java's strong type system and extensive library support, ensuring accurate and reliable application behavior.