composer 安装 laravel 更换下载源

1.在确认cmd 下载好composer

2. composer -V

3. composer config -g repo.packagist composer https://packagist.phpcomposer.com

4.composer create-project laravel/laravel your-project-name --prefer-dist "5.3.*"

your-project-name  自己取一个项目名称

3是版本,可以调整