composer是什么

composer是PHP的插件依赖管理工具，我个人感觉和java的Maven、Gradle很类似。

Windows OS下安装composer

参考：
https://www.php.cn/php-weizijiaocheng-400785.html

https://blog.csdn.net/Zhihua_W/article/details/80407703

composer模板

在项目根目录下创建一个：
composer.json

{
  "name": "nightP",
  "description": "PHP Framework",
  "type": "PHP Framework",
  "require": {
    "php": ">=5.3.0",
    "filp/whoops": "*",
    "symfony/var-dumper": "*"
  },
  "repositories": {
    "packagist": {
      "type": "composer",
      "url": "https://packagist.phpcomposer.com"
    }
  }
}

第一次安装插件

cd进到项目目录，使用命令

composer install

添加插件

composer update