Important Web Design and Development Short Questions

Answer: A servlet handles different HTTP request types by overriding methods like doGet() and doPost(). The service() method checks the type of HTTP request (GET, POST, etc.) and calls the appropriate method to process the request and generate a response based on the request type.

Answer: The getParameter() method retrieves the value of a specific form parameter as a String. It is used to access individual form fields submitted by the user. If the parameter is not present, it returns null, and if the field is empty, it returns an empty String.

Answer: The getParameterValues() method returns an array of Strings containing all values for a specified request parameter, allowing for multiple values. In contrast, getParameter() returns a single String value, which is suitable for parameters with only one value.

Answer: The getParameterNames() method returns an Enumeration of Strings that contains the names of all parameters included in the request. This is useful for iterating over all parameter names when the exact names are not known in advance.

Answer: The GET method appends form data to the URL as query parameters, making it visible in the browser’s address bar and suitable for data that can be cached or bookmarked. The POST method includes form data in the request body, which is not visible in the URL and is used for sending sensitive or large amounts of data.

Answer: The web.xml file is the deployment descriptor for a servlet application. It defines servlet mappings, such as URL patterns and servlet class names, and provides configuration details for servlets. It is essential for specifying how servlets are accessed and configured within the web application.

Answer: The three main stages of the servlet lifecycle are: Initialize, Service, and Destroy. During initialization, the servlet is loaded and the init() method is called. The service stage handles client requests through the service() method. Finally, during destruction, the destroy() method is invoked to release resources before the servlet is removed from memory.

Answer: Initialization parameters are defined in web.xml using <init-param> tags. Each <init-param> contains a <param-name> tag for the parameter name and a <param-value> tag for the parameter value. Multiple <init-param> entries can be included within the <servlet> tag to provide different parameters for the servlet.

Answer: Initialization parameters can be accessed in a servlet using the ServletConfig object. The getInitParameter() method retrieves the value of a parameter by its name. This can be done within the init() method or any other method by first obtaining the ServletConfig object with getServletConfig(). For example: String name = config.getInitParameter("paramName");.

Answer: response.sendRedirect() sends a new request to the specified URL and changes the URL in the browser, making it visible to the client. It does not retain the original request object. In contrast, RequestDispatcher.forward() forwards the request internally within the same application context, keeping the original request and response objects intact. The URL in the browser does not change with forwarding.