Which HTTP methods should be used to send user data for authentication or login?

To send user data during authentication or login, the HTTP POST method is usually used. This is because POST allows data to be transmitted in the request body, which is safer and more convenient for transmitting confidential information (such as passwords).

GET is not recommended because parameters are passed in the URL, which can lead to data leaks through logs or browser history.

Example of sending authentication data using POST in Java (using HttpURLConnection):

URL url = new URL("https://example.com/login");
HttpURLConnection con = (HttpURLConnection) url.openConnection();
con.setRequestMethod("POST");
con.setDoOutput(true);

String postData = "username=user&password=pass";
try(OutputStream os = con.getOutputStream()) {
    byte[] input = postData.getBytes("utf-8");
    os.write(input, 0, input.length);
}

int responseCode = con.getResponseCode();
// Handle response