关于PHP管理依赖工具 Composer 安装与使用

Composer 是PHP中用来管理依赖(dependency)关系的工具。你可以在自己的项目中声明所依赖的外部工具库(libraries)，Composer会帮你安装这些依赖的库文件。

PHP Composer 安装

系统需求：

Composer 需要PHP5.3.2+ 以上的环境来运行。有几个敏感的PHP设置和编译标志也是必需的，但安装程序会发出警告当存在任何不兼容的情况。

比如PHP的扩展的要求是，安装或重新编译php without –disable-phar

为了从源地址安装软件包，而不是简单的压缩文件包，您将需要安装软件包的版本控制工具，比如git、svn或hg等。

Composer 是兼容多平台的，其运行适用于Windows，Linux和OSX。

安装失败的错误消息：

curl -sS https://getcomposer.org/installer | PHP 
#!/usr/bin/env php 
some settings on your machine make Composer unable to work properly. 
Make sure that you fix the issues listed below and run this script again:

The phar extension is missing. 
Install it or recompile php without –disable-phar

Your PHP (5.2.9) is too old, you must upgrade to PHP 5.3.2 or higher.

我的本地默认开发环境是PHP 5.2.9，当我尝试在PHP 5.2.9上安装时，提示版本过低，需要升级到PHP 5.3.2 或者更高的版本。

于是我下载XAMPP 1.7.7 usb lite 版本。

E:\USB\Dropbox\phpstorm\php53>E:\USB\xampp_177\php\php.exe -v 
PHP 5.3.8 (cli) (built: Aug 23 2011 11:50:20) 
Copyright (c) 1997-2011 The PHP Group 
Zend Engine v2.3.0, Copyright (c) 1998-2011 Zend Technologies

XAMPP 1.7.7 下的PHP环境是5.3.8。确认我的PHP环境大于等于PHP5.3.2后。

PHP 5.3 安装 Composer

E:\USB\Dropbox\phpstorm\php53>curl -sS https://getcomposer.org/installer | E:\USB\xampp_177\php\php.exe 
#!/usr/bin/env php 
Some settings on your machine may cause stability issues with Composer. 
If you encounter issues, try to change the following:

The openssl extension is missing, which will reduce the security and stability o 
f Composer. 
If possible you should enable it or recompile php with –with-openssl

Downloading…

Composer successfully installed to: E:\USB\Dropbox\phpstorm\php53\composer.phar 
Use it: php composer.phar

注意：

我关闭了XAMPP 1.7.7 Apache的SSL模块，所以Composer提示我警告，为了安全因素建议我开启SSL模块。不开启也不影响使用。
安装时的参数 | PHP，一定要更改为真实的PHP环境路径，比如 | E:\USB\xampp_177\php\php.exe
使用Composer为PHP路径 + 命令，在我们安装的环境中，使用方法为：E:\USB\xampp_177\php/php.exe composer.phar 命令。
我安装的环境是在Windows下，如果在Linux下，而PHP 5.3 环境也不在默认PHP命令下时，应该采用 | /usr/php/53/usr/bin/php，例如：

curl -sS https://getcomposer.org/installer | /usr/php/53/usr/bin/php

安装完成后，检查安装版本。

E:\USB\Dropbox\phpstorm\php53>E:\USB\xampp_177\php/php.exe composer.phar -V 
Composer version 0209bd31a0ac3aeb2a68fc81e2d03c71072bef33

检查PHP Composer命令：

E:\USB\Dropbox\phpstorm\php53>E:\USB\xampp_177\php/php.exe composer.phar 
  ______ 
 / ____/___ ____ ___ ____ ____ ________ _____ 
/ /  / __ \/ __ `__ \/ __ \/ __ \/ ___/ _ \/ ___/ 
/ /___/ /_/ / / / / / / /_/ / /_/ (__ ) __/ / 
\____/\____/_/ /_/ /_/ .___/\____/____/\___/_/ 
          /_/ 
Composer version 0209bd31a0ac3aeb2a68fc81e2d03c71072bef33

Usage: 
 [options] command [arguments]

Options: 
 –help      -h Display this help message. 
 –quiet     -q Do not output any message. 
 –verbose    -v Increase verbosity of messages. 
 –version    -V Display this application version. 
 –ansi       Force ANSI output. 
 –no-ansi      Disable ANSI output. 
 –no-interaction -n Do not ask any interactive question. 
 –profile      Display timing and memory usage information 
 –working-dir  -d If specified, use the given directory as working directory 
.

Available commands: 
 about      Short information about Composer 
 archive     Create an archive of this composer package 
 config      Set config options 
 create-project  Create new project from a package into given directory. 
 depends     Shows which packages depend on the given package 
 diagnose     Diagnoses the system to identify common errors. 
 dump-autoload  Dumps the autoloader 
 dumpautoload   Dumps the autoloader 
 help       Displays help for a command 
 init       Creates a basic composer.json file in current directory. 
 install     Installs the project dependencies from the composer.lock file 
if present, or falls back on the composer.json. 
 list       Lists commands 
 require     Adds required packages to your composer.json and installs the 
m 
 run-script    Run the scripts defined in composer.json. 
 search      Search for packages 
 self-update   Updates composer.phar to the latest version. 
 selfupdate    Updates composer.phar to the latest version. 
 show       Show information about packages 
 status      Show a list of locally modified packages 
 update      Updates your dependencies to the latest version according to 
composer.json, and updates the composer.lock file. 
 validate     Validates a composer.json

这样我们在PHP5.3环境下的Composer已经安装完成。

类似的方法我们也可以安装PHP 5.4的环境上。

PHP 5.4 安装 Composer

下载XAMPP 1.8.1 usb lite 版本，将得到PHP5.4.7环境。

E:\USB\Dropbox\phpstorm\php53>E:\USB\xampp_181\php\php.exe -v 
PHP 5.4.7 (cli) (built: Sep 12 2012 23:48:31) 
Copyright (c) 1997-2012 The PHP Group 
Zend Engine v2.4.0, Copyright (c) 1998-2012 Zend Technologies

确定版本高于PHP 5.3.2 后，开始安装：

E:\USB\Dropbox\phpstorm\php54>curl -sS https://getcomposer.org/installer | E:\USB\xampp_181\php\php.exe 
#!/usr/bin/env php 
Some settings on your machine may cause stability issues with Composer. 
If you encounter issues, try to change the following:

The openssl extension is missing, which will reduce the security and stability o 
f Composer. 
If possible you should enable it or recompile php with –with-openssl

Downloading…

Composer successfully installed to: E:\USB\Dropbox\phpstorm\php54\composer.phar 
Use it: php composer.phar

安装完成后，检查安装版本。

E:\USB\Dropbox\phpstorm\php54>E:\USB\xampp_181\php/php.exe composer.phar -V 
Composer version 0209bd31a0ac3aeb2a68fc81e2d03c71072bef33

这样，PHP 5.4 环境下的Composer也安装成功了。

PHP Composer 使用

这里我只简单演示使用PHP Composer安装Symfony框架。

首先大概讲解一下命令的标准格式：

php composer.phar create-project symfony/framework-standard-edition path/ 2.2.1

第一个参数PHP为本地PHP开发环境，指向PHP运行命令。
第二个参数，为composer.phar方式下载。
第三个参数，为动作命令，例如create-project，目的是为了创建一个新的项目从一个软件包到指定目录。
第四个参数，为本地安装的目录。
第五个参数，为安装软件包的版本。

根据上述我们在PHP5.4环境下安装的Composer，我们的安装命令为：

E:\USB\Dropbox\phpstorm\php54>E:\USB\xampp_181\php/php.exe composer.phar create-project symfony/framework-standard-edition E:\USB\xampp_181\htdocs\Symfony 2.2.1

安装结果：

Installing symfony/framework-standard-edition (v2.2.1) 
 – Installing symfony/framework-standard-edition (v2.2.1) 
  Downloading: 100%
Created project in E:\USB\xampp_181\htdocs\Symfony 
Loading composer repositories with package information 
Installing dependencies from lock file 
 – Installing doctrine/lexer (v1.0) 
  Downloading: 100%
 – Installing doctrine/annotations (v1.1) 
  Downloading: 100%
 – Installing doctrine/cache (v1.0) 
  Downloading: 100%
 – Installing doctrine/collections (v1.1) 
  Downloading: 100%
 – Installing twig/twig (v1.12.2) 
  Downloading: 100%
 – Installing psr/log (1.0.0) 
  Downloading: 100%
 – Installing doctrine/inflector (v1.0) 
  Downloading: 100%
 – Installing doctrine/common (2.4.0-RC1) 
  Downloading: 100%
 – Installing symfony/symfony (v2.2.1) 
  Downloading: 100%
 – Installing jdorn/sql-formatter (v1.2.0) 
  Downloading: 100%
 – Installing doctrine/dbal (2.3.3) 
  Downloading: 100%
 – Installing doctrine/doctrine-bundle (v1.2.0-beta1) 
  Downloading: 100%
 – Installing doctrine/orm (2.3.3) 
  Downloading: 100%
 – Installing jms/cg (1.0.0) 
  Downloading: 100%
 – Installing phpoption/phpoption (1.2.0) 
  Downloading: 100%
 – Installing jms/parser-lib (1.0.0) 
  Downloading: 100%
 – Installing jms/metadata (1.3.0) 
  Downloading: 100%
 – Installing jms/aop-bundle (1.0.0) 
  Downloading: 100%
 – Installing jms/di-extra-bundle (1.3.0) 
  Downloading: 100%
 – Installing jms/security-extra-bundle (1.4.0) 
  Downloading: 100%
 – Installing sensio/distribution-bundle (v2.2.1) 
  Downloading: 100%
 – Installing sensio/framework-extra-bundle (v2.2.1) 
  Downloading: 100%
 – Installing sensio/generator-bundle (v2.2.1) 
  Downloading: 100%
 – Installing kriswallsmith/assetic (v1.1.0-alpha4) 
  Downloading: 100%
 – Installing symfony/assetic-bundle (v2.1.2) 
  Downloading: 100%
 – Installing monolog/monolog (1.4.1) 
  Downloading: 100%
 – Installing symfony/monolog-bundle (v2.2.0) 
  Downloading: 100%
 – Installing swiftmailer/swiftmailer (v4.3.0) 
  Downloading: 100%
 – Installing symfony/swiftmailer-bundle (v2.2.0) 
  Downloading: 100%
 – Installing twig/extensions (v1.0.0) 
  Downloading: 100%

kriswallsmith/assetic suggests installing leafo/lessphp (Assetic provides the integration with the lessphp LESS compiler) 
kriswallsmith/assetic suggests installing leafo/scssphp (Assetic provides the integration with the scssphp SCSS compiler) 
kriswallsmith/assetic suggests installing leafo/scssphp-compass (Assetic provides the integration with the SCSS compass plugin) 
kriswallsmith/assetic suggests installing ptachoire/cssembed (Assetic provides the integration with phpcssembed to embed data uris) 
monolog/monolog suggests installing doctrine/couchdb (Allow sending log messages to a CouchDB server) 
monolog/monolog suggests installing ext-amqp (Allow sending log messages to an AMQP server (1.0+ required)) 
monolog/monolog suggests installing ext-mongo (Allow sending log messages to a MongoDB server) 
monolog/monolog suggests installing mlehner/gelf-php (Allow sending log messages to a GrayLog2 server) 
monolog/monolog suggests installing raven/raven (Allow sending log messages to a Sentry server) 
Generating autoload files 
Clearing the cache for the dev environment with debug true 
Installing assets using the hard copy option 
Installing assets for Symfony\Bundle\FrameworkBundle into web/bundles/framework 
Installing assets for Acme\DemoBundle into web/bundles/acmedemo 
Installing assets for Sensio\Bundle\DistributionBundle into web/bundles/sensiodistribution

从命令行结果，我们看到了整个Symfony框架的安装过程与结果。

PHP Composer 定义依赖关系

Composer在使用时会自动寻找composer.json这个文件。 composer.json将用来定义整个项目的依赖包。例如：

{ 
  "require": { 
    "monolog/monolog": "1.2.*" 
  } 
}

依赖包简单的说明，我们的项目需要一些从1.2开始的任何版本的monolog/monolog包。

Composer是PHP中的一个依赖关系管理工具。通过Composer我们可以在发布软件时节省大量的文件数目和控制依赖包的版本。

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