Why Doesn't Java's HttpURLConnection Follow HTTP to HTTPS Redirects?

Java's HttpURLConnection Fails to Follow HTTP to HTTPS Redirects: A Security Measure

Java's HttpURLConnection, a class used to establish connections with HTTP servers, exhibits a peculiar behavior when it comes to redirecting from HTTP to HTTPS URLs. This behavior, where the redirect is not followed, may seem counterintuitive to developers.

The root of this behavior lies in the security considerations implemented by HttpURLConnection. Redirects are only followed when they adhere to the same protocol. In the case of HTTP to HTTPS redirects, the protocols are different, and there is no mechanism to disable this protocol validation check.

HTTPS, despite being a mirrored version of HTTP, is considered a distinct protocol from the HTTP perspective. Therefore, following a redirect from HTTP to HTTPS without user consent is deemed unsafe.

This security measure safeguards against potential vulnerabilities. Imagine an application that automatically performs client authentication via HTTP. A user may expect to browse anonymously, but an unprompted redirect to HTTPS would expose their identity to the server.

Thus, Java's HttpURLConnection does not follow HTTP to HTTPS redirects as a proactive security measure to prevent unauthorized access and protect user privacy.

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