$request = Yii::$app->request;

 $get = $request->get();

 // 等同于: $get = $_GET;

 $id = $request->get('id');

 // 等同于: $id = isset($_GET['id']) ? $_GET['id'] : null;

 $id = $request->get('id', 1);

 // 等同于: $id = isset($_GET['id']) ? $_GET['id'] : 1;

 //添加了默认值

 $post = $request->post();

 // equivalent to: $post = $_POST;

 $name = $request->post('name');

 // 等同于: $name = isset($_POST['name']) ? $_POST['name'] : null;

 $name = $request->post('name', '');

 // 等同于: $name = isset($_POST['name']) ? $_POST['name'] : '';

 //添加了默认值

 $request = Yii::$app->request;

 if ($request->isAjax) { // 判断是否为AJAX 请求 }

 if ($request->isGet)  { // 判断是否为GET 请求 }

 if ($request->isPost) { // 判断是否为POST 请求}

 if ($request->isPut)  { // 判断是否为PUT 请求 }

// $headers is an object of yii\web\HeaderCollection

$headers = Yii::$app->request->headers;

// 返回header头部所有信息

$accept = $headers->get('Accept');

if ($headers->has('User-Agent')) { // 获取User-Agent }

 $userHost = Yii::$app->request->userHost;

 $userIP = Yii::$app->request->userIP;