需要cakephp的Auth组件配置细节吗？

Would someone pease explain this function to me in its entirety? i.e what the function beforeFilter does and what each line is doing. Thanks.

function beforeFilter()
{
    //Configure AuthComponent
    $this->Auth->authorize = 'actions';
    $this->Auth->actionPath = 'controllers/';

    $this->Auth->loginAction = array('controller' => 'users', 'action' => 'login');
    $this->Auth->loginRedirect = array('controller' => 'posts', 'action' => 'add');

    $this->Auth->logoutRedirect = array('controller' => 'users', 'action' => 'login');
}

Documented Code

// `beforeFilter()` gets executed before the request forwarded to `action`
function beforeFilter() {
    //Configure AuthComponent
    // read http://book.cakephp.org/complete/1250/Authentication#authorize-1275
    $this->Auth->authorize = 'actions';

    // read http://book.cakephp.org/complete/1250/Authentication#actionPath-1279
    $this->Auth->actionPath = 'controllers/';

    // tells the Auth component the location of login action
    $this->Auth->loginAction = array('controller' => 'users', 'action' => 'login');

    // tells the Auth component where to redirect after successful login
    $this->Auth->loginRedirect = array('controller' => 'posts', 'action' => 'add');

    // tells the Auth component where to redirect after logout
    $this->Auth->logoutRedirect = array('controller' => 'users', 'action' => 'login'); }

Your must read this http://book.cakephp.org/complete/1250/Authentication