composer install 会根据composer.lock文件来安装依赖包,这里composer.lock占据“主导地位”,如果.lock文件不存在,将读取composer.json文件找出需要安装的包,并在处理完依赖后创建composer.lock。原文出处
原文 Add composer.json with some dependencies Run composer install Add some more dependencies Run composer update as you've updated your dependencies