YII2.0自带的有2个项目目录一个是前台的frontend和后台的backend,访问的时候必须访问至http://localhost:8080/phpblog/backend/web/index.php?r=admin/index,这样好像很麻烦，而且难记，于是我们把访问的地址配置成http://localhost:8080/phpblog/admin.php这种的就好记很多了.

首先在backend下面找到web目录:

把里面的index.php复制到根目录并改名字为admin.php:

修改admin.php里面的内容为:

<?php
defined('YII_DEBUG') or define('YII_DEBUG', true);
defined('YII_ENV') or define('YII_ENV', 'dev');

require(__DIR__ . '/vendor/autoload.php');
require(__DIR__ . '/vendor/yiisoft/yii2/Yii.php');
require(__DIR__ . '/common/config/bootstrap.php');
require(__DIR__ . '/backend/config/bootstrap.php');

#require(__DIR__ . '/common/config/autoload.php');

$config = yii\helpers\ArrayHelper::merge(
    require(__DIR__ . '/common/config/main.php'),
    require(__DIR__ . '/common/config/main-local.php'),
    require(__DIR__ . '/backend/config/main.php'),
    require(__DIR__ . '/backend/config/main-local.php')
);

$application = new yii\web\Application($config);
$application->language='zh-CN';
$application->defaultRoute='admin';
$application->run();

下面进行js，css路径修改:

找到backend目录下面的assets目录下面的AppAsset.php，修改内容

class AppAsset extends AssetBundle
{
    public $basePath = '@webroot';
    public $baseUrl = '@web';
    //全局的js和css，主要是修改这里的路径，原来的@web不能使用了，要写backend的全路径了，按照下面的写就可以了
    public $css = [
        'backend/web/scripts/css/default.css',
        'backend/web/scripts/js/jquery-easyui-1.4.3/themes/icon.css',
        'backend/web/scripts/js/jquery-easyui-1.4.3/themes/easyui_icons.css',
        'backend/web/scripts/js/jquery-easyui-1.4.3/themes/default/easyui.css'
    ];
    public $js = [
        'backend/web/scripts/js/jquery-easyui-1.4.3/jquery.min.js',
        'backend/web/scripts/js/jquery-easyui-1.4.3/jquery.easyui.min.js'
    ];
    public $depends = [
        
    ];
    //定义按需加载JS方法，注意加载顺序在最后  
    public static function addScript($view, $jsfile) {  
        $view->registerJsFile($jsfile, ['depends'=>['backend\assets\AppAsset']]);  
    }  
      
   //定义按需加载css方法，注意加载顺序在最后  
    public static function addCss($view, $cssfile) {  
        $view->registerCssFile($cssfile, ['depends'=>['backend\assets\AppAsset']]);  
    }  

}

继续修改backend下面的config目录下面的main.php:

<?php
$params = array_merge(
    require(__DIR__ . '/../../common/config/params.php'),
    require(__DIR__ . '/../../common/config/params-local.php'),
    require(__DIR__ . '/params.php'),
    require(__DIR__ . '/params-local.php')
);
 
return [
    'id' => 'app-backend',
    'basePath' => dirname(__DIR__),
    'bootstrap' => ['log'],
    'controllerNamespace' => 'backend\controllers',
    'components' => [

        //添加了这个配置
        'assetManager' => [
            'basePath' => '@webroot/backend/web/assets',
            'baseUrl' => '@web/backend/web/assets'
        ],
        'user' => [
            'identityClass' => 'common\models\User',
            'enableAutoLogin' => true,
        ],
        'log' => [
            'traceLevel' => YII_DEBUG ? 3 : 0,
            'targets' => [
                [
                    'class' => 'yii\log\FileTarget',
                    'levels' => ['error', 'warning'],
                ],
            ],
        ],
        'errorHandler' => [
            'errorAction' => 'site/error',
        ],
    ],
    'params' => $params,
];

控制器一定要和配置的defaultRoute默认路由对应，我们配置的是admin，那么就要有对应的AdminController.php，里面的方法必须为actionIndex，这样访问的时候就可以直接运行里面的view了：

运行效果：

希望可以帮助到大家。