我如何检查Android apk是用发布而不是调试证书签名的?

我用PHP7在Ubuntu 16.04服务器上运行laravel 5.4。安装cviebrock/eloquent-sluggable包时抛出一些错误:

pish@let:/home/sherk/ftp/www$ sudo composer require cviebrock/eloquent-sluggable
Do not run Composer as root/super user! See https://getcomposer.org/root for details
Using version ^4.2 for cviebrock/eloquent-sluggable
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - phpunit/php-code-coverage 4.0.7 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - phpunit/php-code-coverage 4.0.7 requires ext-dom * -> the requested PHP extension dom is missing from your system.
    - Installation request for phpunit/php-code-coverage (installed at 4.0.7) -> satisfiable by phpunit/php-code-coverage[4.0.7].

  To enable extensions, verify that they are enabled in those .ini files:
    - /etc/php/7.0/cli/php.ini
    - /etc/php/7.0/cli/conf.d/10-mysqlnd.ini
    - /etc/php/7.0/cli/conf.d/10-opcache.ini
    - /etc/php/7.0/cli/conf.d/10-pdo.ini
    - /etc/php/7.0/cli/conf.d/20-calendar.ini
    - /etc/php/7.0/cli/conf.d/20-ctype.ini
    - /etc/php/7.0/cli/conf.d/20-exif.ini
    - /etc/php/7.0/cli/conf.d/20-fileinfo.ini
    - /etc/php/7.0/cli/conf.d/20-ftp.ini
    - /etc/php/7.0/cli/conf.d/20-gd.ini
    - /etc/php/7.0/cli/conf.d/20-gettext.ini
    - /etc/php/7.0/cli/conf.d/20-iconv.ini
    - /etc/php/7.0/cli/conf.d/20-json.ini
    - /etc/php/7.0/cli/conf.d/20-mbstring.ini
    - /etc/php/7.0/cli/conf.d/20-mcrypt.ini
    - /etc/php/7.0/cli/conf.d/20-mysqli.ini
    - /etc/php/7.0/cli/conf.d/20-pdo_mysql.ini
    - /etc/php/7.0/cli/conf.d/20-phar.ini
    - /etc/php/7.0/cli/conf.d/20-posix.ini
    - /etc/php/7.0/cli/conf.d/20-readline.ini
    - /etc/php/7.0/cli/conf.d/20-shmop.ini
    - /etc/php/7.0/cli/conf.d/20-sockets.ini
    - /etc/php/7.0/cli/conf.d/20-sysvmsg.ini
    - /etc/php/7.0/cli/conf.d/20-sysvsem.ini
    - /etc/php/7.0/cli/conf.d/20-sysvshm.ini
    - /etc/php/7.0/cli/conf.d/20-tokenizer.ini
  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.

Installation failed, reverting ./composer.json to its original content.

我在本地版本的应用程序上安装这个包没有问题。

我目前正在一台运行CentOs的服务器上配置hadoop。当我运行start-dfs.sh或stop-dfs.sh时，我得到以下错误:

警告跑龙套。NativeCodeLoader:无法加载原生hadoop库 你的平台……在适用的地方使用内置java类

我运行的是Hadoop 2.2.0。

我在网上搜索了一下，找到了这个链接:http://balanceandbreath.blogspot.ca/2013/01/utilnativecodeloader-unable-to-load.html

但是，hadoop 2上的/native/目录的内容。x似乎不同，所以我不知道该怎么办。

我还在hadoop-env.sh中添加了以下两个环境变量:

出口HADOOP_OPTS = " HADOOP_OPTS美元 -Djava.library.path = / usr /地方/ hadoop / lib /” 出口HADOOP_COMMON_LIB_NATIVE_DIR = " / usr /地方/ hadoop / lib /本地/”

什么好主意吗?

我正在学习Elixir，想知道为什么它有两种类型的函数定义:

使用def定义在模块中的函数，使用myfunction(param1, param2)调用 使用fn定义的匿名函数，使用myfn调用。(param1 param2)

Only the second kind of function seems to be a first-class object and can be passed as a parameter to other functions. A function defined in a module needs to be wrapped in a fn. There's some syntactic sugar which looks like otherfunction(&myfunction(&1, &2)) in order to make that easy, but why is it necessary in the first place? Why can't we just do otherfunction(myfunction))? Is it only to allow calling module functions without parenthesis like in Ruby? It seems to have inherited this characteristic from Erlang which also has module functions and funs, so does it actually comes from how the Erlang VM works internally?

有两种类型的函数并从一种类型转换为另一种类型以便将它们传递给其他函数有任何好处吗?使用两种不同的表示法调用函数是否有好处?

如何通过RStudio更新R ?

我正在开发一个带有服务的Android 2.3.3应用程序。我在这个服务中有这个来与Main活动通信:

public class UDPListenerService extends Service
{
    private static final String TAG = "UDPListenerService";
    //private ThreadGroup myThreads = new ThreadGroup("UDPListenerServiceWorker");
    private UDPListenerThread myThread;
    /**
     * Handler to communicate from WorkerThread to service.
     */
    private Handler mServiceHandler;

    // Used to receive messages from the Activity
    final Messenger inMessenger = new Messenger(new IncomingHandler());
    // Use to send message to the Activity
    private Messenger outMessenger;

    class IncomingHandler extends Handler
    {
        @Override
        public void handleMessage(Message msg)
        {
        }
    }

    /**
     * Target we publish for clients to send messages to Incoming Handler.
     */
    final Messenger mMessenger = new Messenger(new IncomingHandler());
    [ ... ]
}

在这里，final Messenger mMessenger = new Messenger(new IncomingHandler());，我得到以下Lint警告:

这个Handler类应该是静态的，否则可能会发生泄漏

这是什么意思?

在计算之后，我希望显示一个弹出框或警告框，向用户传递消息。有人知道我在哪里可以找到更多的信息吗?

我怎么能把一些文本放入一个文本框，这将被自动删除时，用户键入的东西在它?

我在Flutter应用程序中有两个屏幕:记录列表和创建和编辑记录的屏幕。

如果我传递一个对象到第二个屏幕，这意味着我将编辑这个，如果我传递null，这意味着我正在创建一个新项目。编辑屏幕是一个有状态的小部件，我不确定如何使用这种方法https://flutter.io/cookbook/navigation/passing-data/。

class RecordPage extends StatefulWidget {
  final Record recordObject;

  RecordPage({Key key, @required this.recordObject}) : super(key: key);

  @override
  _RecordPageState createState() => new _RecordPageState();
}

class _RecordPageState extends State<RecordPage> {
  @override
  Widget build(BuildContext context) {
   //.....
  }
}

我怎么能访问recordObject内_RecordPageState?

在Laravel 5.4上使用php artisan make:auth迁移错误

[Illuminate\Database\QueryException] SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes (SQL: alter tabl e users add unique users_email_unique(email)) [PDOException] SQLSTATE[42000]: Syntax error or access violation: 1071 Specified key was too long; max key length is 767 bytes