Detailed explanation of the steps to implement single sign-on in Yii2

<?php
// Session 跨域
$host = explode(&#39;.&#39;, $_SERVER["HTTP_HOST"]);
if (count($host) > 2) {
  define(&#39;DOMAIN&#39;, $host[1] . &#39;.&#39; . $host[2]);
} else {
  define(&#39;DOMAIN&#39;, $host[0] . &#39;.&#39; . $host[1]);
}

<?php
&#39;user&#39; => [
  &#39;identityClass&#39; => &#39;common\models\User&#39;,
  &#39;enableAutoLogin&#39; => true,
  &#39;identityCookie&#39; => [&#39;name&#39; => &#39;_identity&#39;, &#39;httpOnly&#39; => true, &#39;domain&#39; => &#39;.&#39;.DOMAIN],
],
&#39;session&#39; => [
  &#39;cookieParams&#39; => [&#39;domain&#39; => &#39;.&#39;.DOMAIN, &#39;lifetime&#39; => 0],
  &#39;timeout&#39; => 3600,
],

<?php
//设置
Yii::$app->session[&#39;var&#39;]=&#39;value&#39;;
//使用
echo Yii::$app->session[&#39;var&#39;];
//移除
unset(Yii::$app->session[&#39;var&#39;]);