所有项目都会使用该镜像地址：
composer config -g repo.packagist composer https://mirrors.aliyun.com/composer/
取消配置：
composer config -g --unsetrepos.packagist
项目配置
仅修改当前工程配置，仅当前工程可使用该镜像地址：
composer config repo.packagist composer https://mirrors.aliyun.com/composer/
取消配置：
composer config --unsetrepos.packagist
调试
composer 命令增加 -vvv 可输出详细的信息，命令如下：
composer -vvvrequirealibabacloud/sdk
