common/config/main.php

'language' => 'zh-CN', //yii2默认使用‘en-US’若要设置中文可用

'components' => [

        'i18n' => [
            'translations' => [
                'app*' => [
                    'class' => 'yii\i18n\PhpMessageSource',
                    'basePath' => '@common/messages',
                    'sourceLanguage' => 'en-US',
                    'fileMap' => [
                        'app' => 'app.php',
                        'app/error' => 'error.php',
                    ],
                ],
            ],
        ],


]

执行命令生成i18n设置文件

php yii message/config @common/config/i18n.php

return [
    'color' => null,
    'interactive' => true,
    'help' => null,
    'silentExitOnException' => null,
    'sourcePath' => '@rootPath',  //设置为项目跟地址，检索全项目  bootstrap:（Yii::setAlias('@rootPath', dirname(dirname(__DIR__)));）
    'messagePath' => '@common/messages', //config设置的basePath，若无messages文件夹需要自己创建
    'languages' => ['zh-CN'],  //设置需要转换的语言
    'translator' => 'Yii::t',
    'sort' => false,
    'overwrite' => true,
    'removeUnused' => false,
    'markUnused' => true,
    'except' => [
        '.svn',
        '.git',
        '.gitignore',
        '.gitkeep',
        '.hgignore',
        '.hgkeep',
        '/messages',
        '/BaseYii.php',
        'vendor',  //排除依赖
    ],
    'only' => [
        '*.php',
    ],
    'format' => 'php',
    'db' => 'db',
    'sourceMessageTable' => '{{%source_message}}',
    'messageTable' => '{{%message}}',
    'catalog' => 'messages',
    'ignoreCategories' => [],
    'phpFileHeader' => '',
    'phpDocBlock' => null,
];

执行命令生成映射文件

php yii message @common/config/i18n.php

文件在common/messages/zh-CN/app.php

使用

Yii::t('app', 'This is a english message!')

动态更改返回中英文

//BaseController
public function beforeAction($action)
{
    if (!Yii::$app->request->isOptions) {
            if (Yii::$app->request->headers->get('language')) {
                Yii::$app->language = Yii::$app->request->headers->get('language') ?: 'en-US';
            }
        }
        return parent::beforeAction($action); 
}