composer的安裝和使用

　　因爲工做中須要用到leancloud的LeanCloud PHP SDK，支持composer安裝，因此就下載composer工具了，

　　安裝以前能夠用composer命令檢測是否已經安裝了，命令是：composer直接回車，若是顯示command not found: composer表示還未安裝；若是顯示了composer的圖標表示已經安裝了。

Suppose:

You have a project that depends on a number of libraries.
Some of those libraries depend on other libraries.
Composer:

Enables you to declare the libraries you depend on.
Finds out which versions of which packages can and need to be installed, and installs them (meaning it downloads them into your project).

　　安裝步驟：　　

　　1.php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
　　2.php -r "if (hash_file('SHA384', 'composer-setup.php') === 'e115a8dc7871f15d853148a7fbac7da27d6c0030b848d9b3dc09e2a0388afed865e6a3d6b3c0fad45c48e2b5fc1196ae') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
　　3.php composer-setup.php
　　4.php -r "unlink('composer-setup.php');"

　　5.把composer.phar移動到環境變量裏，同時把composer.phar重命名爲composer，用命令 mv composer.phar /usr/local/bin/composer

　　

　　使用方法：

　　1.在你的項目目錄使用composer，切換到你的項目目錄，命令 cd /Applications/MAMP/htdocs/DPOpenAPI/

　　2.下載你須要的文件，命令 composer require leancloud/leancloud-sdk