'custom' => [
        'title' => [
            'required' => '标题不能为空',
        ],
    ],

找到resources/lang/en/validation.php中的custome，这个满足你的要求不？更多的Laravel 5教程：

https://laravist.com/series/laravel-5-basic

$this - > validate($request, [
        'title' = > 'required|integer|between:1,5',
], [
        'title.required' = > 'title必填',
        'title.between' = > 'title字数必须在1到5个之间',
]);

亲测可用