How to Retrieve the Referring URL in a Java Servlet Using HttpServletRequest

How can I retrieve the referring URL in a Java Servlet using HttpServletRequest?

String referrer = request.getHeader("Referer");

To log URLs that link to your site in a Java servlet, you can utilize the `HttpServletRequest` object to access the HTTP headers, specifically the 'Referer' header, which provides the URL of the page that linked to the current request.

String referrer = request.getHeader("Referer");
if (referrer != null) {
    // Log the referring URL
    System.out.println("Referring URL: " + referrer);
} else {
    // Handle the case where the referrer is not available
    System.out.println("No referring URL available.");
}

Causes

• Web browsers often send the 'Referer' header with requests, indicating the previous page that the user navigated from.
• Some browsers or privacy settings may block or not send the 'Referer' header, resulting in it being null or empty.

Solutions

• Use `request.getHeader("Referer")` to retrieve the referring URL from the request headers.
• Ensure you handle potential null values gracefully in your code to avoid null pointer exceptions.

Mistake: Assuming the referer header is always present.

Solution: Implement checks for null or empty values when retrieving the header.

Mistake: Not configuring the Servlet to handle HTTPS to HTTP redirections properly.

Solution: Ensure your application can handle both HTTP and HTTPS requests and log the referer accordingly.