Use of Yii2 request

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

$get = $request->get(); 
// equivalent to: $get = $_GET;
 
$id = $request->get('id');   
// equivalent to: $id = isset($_GET['id']) ? $_GET['id'] : null;
 
$id = $request->get('id', 1);   
// equivalent to: $id = isset($_GET['id']) ? $_GET['id'] : 1;
//添加了默认值
 
$post = $request->post(); 
// equivalent to: $post = $_POST;
 
$name = $request->post('name');   
// equivalent to: $name = isset($_POST['name']) ? $_POST['name'] : null;
 
$name = $request->post('name', '');   
// equivalent to: $name = isset($_POST['name']) ? $_POST['name'] : '';
//添加了默认值</code>

<code>$request = Yii::$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 }
if ($request->isSecureConnection) { // 判断是否为https 请求}</code>

<code>// $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 }</code>

<code>$userHost = Yii::$app->request->userHost; 
$userIP = Yii::$app->request->userIP;</code>