composer install错误提示：'composer' is not recognized as an internal or external command, operable program or batch file.

E:\phpstudy\PHPTutorial\tools\composer>composer install

Composer could not find a composer.json file in E:\phpstudy\PHPTutorial\tools\composer

To initialize a project, please create a composer.json file as described in the https://getcomposer.org/ "Getting Started" section

E:\phpstudy\PHPTutorial\WWW\my>composer install

'composer' is not recognized as an internal or external command,

operable program or batch file.

我的项目目录：E:\phpstudy\PHPTutorial\WWW\my 两种安装都不行，请问？？？