composer 使用教程常用知识点
使用 composer config -l -g 查看所有全局配置
composer config -l -g
设置国内镜像源一全局配置（以腾讯云为例）
composer config -g repos.packagist composer https://mirrors.tencent.com/composer
-g 指的是全局变量，如果只是单一项目配置，则是
composer config repos.packagist composer https://mirrors.tencent.com/composer
取消全局镜像源配置恢复默认的：
composer config -g --unset repos.packagist
取消当前镜像源配置：
composer config --unset repos.packagist
升级 composer（自动更新）:
composer self-update
查看 composer 版本：
composer --version
如果想输出更多信息，和帮助，可以直接使用 composer -v
清除缓存:
composer clearcache
composer 官方源和镜像源：
composer config -g repo.packagist composer https://repo.packagist.org
全球，CloudFlare：
composer config -g repos.packagist composer https://packagist.pages.dev
日本，（同步频率为2分钟）
composer config -g repos.packagist composer https://packagist.jp
中国，腾讯云（同步频率为每天一次，同步的时间为 凌晨0点-2点）
composer config -g repos.packagist composer https://mirrors.tencent.com/composer
中国，阿里云（实时同步）
composer config -g repo.packagist composer https://mirrors.aliyun.com/composer
中国，上海交通大学（同步频率为每小时）
composer config -g repos.packagist composer https://packagist.mirrors.sjtug.sjtu.edu.cn
欧洲，芬兰（实时同步）
composer config -g repos.packagist composer https://packagist.fi
