Obtener post java html

<html>
<head>
    <title></title>
</head>
<body>
    <form action="register.php" method="post">
        <input type="text" name="username" placeholder="Inserisci lo username" /><br>
        <input type="password" name="password" placeholder="Inserisci la password" /><br>
        <input type="submit" value="Registrati" />
    </form>
</body>
</html>
Greg