public $verifyCode;
public function rules()
{
   return [
      ……
      ['verifyCode', 'captcha', 'on' => 'login'], //验证码
   ];
}
public function scenarios() {
    $scenarios = parent::scenarios();
    $scenarios['login'] = ['username', 'password', 'rememberMe', 'verifyCode'];
    return $scenarios;
}

public function actions()
{
    return [
      'error' => [
        'class' => 'yii\web\ErrorAction',
      ],
      'captcha' => [
        'class' => 'yii\captcha\CaptchaAction',
        'fixedVerifyCode' => YII_ENV_TEST "htmlcode">

<"input-group input-group-lg col-md-8"><span class="input-group-addon"><i class="glyphicon glyphicon-eye-open red"></i></span>{input}<div class="input-group-addon" style="padding:5px;">{image}</div></div>',
          'options' => ['class' => 'form-control','placeholder'=>"验证码"],
          'imageOptions'=>['alt'=>'点击换图','title'=>'点击换图', 'style'=>'cursor:pointer']
 ])->label(false) "_blank" href="//www.jb51.net/Special/386.htm">Yii框架入门及常用技巧总结》、《php优秀开发框架总结》、《smarty模板入门基础教程》、《php面向对象程序设计入门教程》、《php字符串(string)用法总结》、《php+mysql数据库操作入门教程》及《php常见数据库操作技巧汇总》

希望本文所述对大家基于Yii框架的PHP程序设计有所帮助。