我在Windows上安装了开发人员模式，我在安装运行项目所需的一些程序/功能时遇到了很多问题。问题之一是当我运行composer install或composer install --no-plugins --no-scripts时，它总是给我这个错误。
Loading composer repositories with package information
Installing dependencies (including require-dev) from lock file
Your requirements could not be resolved to an installable set of packages.
Problem 1
- Installation request for dompdf/dompdf v0.8.2 -> satisfiable by dompdf/dompdf[v0.8.2].
- dompdf/dompdf v0.8.2 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
Problem 2
- Installation request for erusev/parsedown 1.7.1 -> satisfiable by erusev/parsedown[1.7.1].
- erusev/parsedown 1.7.1 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
Problem 3
- Installation request for laravel/framework v5.5.40 -> satisfiable by laravel/framework[v5.5.40].
- laravel/framework v5.5.40 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
Problem 4
- Installation request for league/csv 8.2.3 -> satisfiable by league/csv[8.2.3].
- league/csv 8.2.3 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
Problem 5
- Installation request for teamtnt/tntsearch v1.3.1 -> satisfiable by teamtnt/tntsearch[v1.3.1].
- teamtnt/tntsearch v1.3.1 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
Problem 6
- Installation request for facebook/webdriver 1.3.0 -> satisfiable by facebook/webdriver[1.3.0].
- facebook/webdriver 1.3.0 requires ext-curl * -> the requested PHP extension curl is missing from your system.
Problem 7
- Installation request for phpunit/phpunit 6.5.8 -> satisfiable by phpunit/phpunit[6.5.8].
- phpunit/phpunit 6.5.8 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
Problem 8
- dompdf/dompdf v0.8.2 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
- barryvdh/laravel-dompdf v0.8.2 requires dompdf/dompdf ^0.8 -> satisfiable by dompdf/dompdf[v0.8.2].
- Installation request for barryvdh/laravel-dompdf v0.8.2 -> satisfiable by barryvdh/laravel-dompdf[v0.8.2].
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-opcache.ini
- /etc/php/7.0/cli/conf.d/10-pdo.ini
- /etc/php/7.0/cli/conf.d/15-xml.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-dom.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-intl.ini
- /etc/php/7.0/cli/conf.d/20-json.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-simplexml.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
- /etc/php/7.0/cli/conf.d/20-wddx.ini
- /etc/php/7.0/cli/conf.d/20-xmlreader.ini
- /etc/php/7.0/cli/conf.d/20-xmlwriter.ini
- /etc/php/7.0/cli/conf.d/20-xsl.ini
You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.
我已经安装了PHP命令php -v
PHP 7.0.30-0ubuntu0.16.04.1 (cli) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies
with Zend OPcache v7.0.30-0ubuntu0.16.04.1, Copyright (c) 1999-2017, by Zend Technologies
此错误的解决方案是安装这两个包：
$sudo apt-get install php-mbstring
$sudo apt-get install php-xml
你的错误非常清楚。您没有在服务器上启用mbstring。请检查php.ini并启用它。再次尝试之前重启服务器。
哟必须确保有所需的PHP扩展ext-mbstring和ext-curl，然后将它们添加到php.ini文件。
请参阅以下有关在Windows上安装php-extensions的文档：http://php.net/manual/de/install.pecl.windows.php