<form method="POST" action="${resource(file: 'j_spring_security_check')}">

    Username:
    <g:textField  class="xlarge" name='j_username' id='j_username' value='${request.remoteUser}' />

    Password:
    <input type='password' class="xlarge"  name='j_password' id='j_password' value='${request.remoteUser}' />

    <g:submitButton name="login" value="Login" /></td>

    </form>