http://getcomposer.org/download/
You must enable the openssl extension to download files via https
解决方法：
在PHP根目录下（）找到php.ini;
Find line ;extension=php_openssl.dll in D:Program FilesEasyPHP-DevServer-13.1VC9inariesphpphp_runningversionphp.ini and uncomment it by removing the semicolon (;) from the beginning of the line.