/dd>
<dt><span class="throwsLabel">Throws:</span></dt>
<dd><code><a href="../../../jakarta/servlet/ServletException.html" title="class in jakarta.servlet">ServletException</a></code> - if the configured login mechanism does not support username password authentication, or
 if a non-null caller identity had already been established (prior to the call to login), or if validation of the
 provided username and password fails.</dd>
<dt><span class="simpleTagLabel">Since:</span></dt>
<dd>Servlet 3.0</dd>
</dl>
</