php – 使用composer安装PEAR扩展名HTTP_Request2

{
    "name": "vendor/Project","description": "description_text","repositories": [
        {
            "type": "pear","url": "http://pear.php.net"
        }
    ],"require": {
        "jakeasmith/http_build_url": "dev-master","phpmailer/phpmailer": "dev-master","pear-pear/Text_Diff": "*","pear-pear/Net_IDNA2": "*","pear-pear/HTTP_Request2": "2.2.1"
    },"require-dev": {
        "phpunit/phpunit": "< 4.0.0"
    }
}

当我试图执行命令php composer.phar install我得到了这个：

Loading composer repositories with package information
Initializing PEAR repository http://pear.php.net
Installing dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for pear-pear/http_request2 2.2.1 -> satisfiable by pear-pear.php.net/HTTP_Request2[2.2.1].
    - pear-pear.php.net/HTTP_Request2 2.2.1 required pear-pear.php.net/net_url2 >=2.0.0.0 -> no matching package found.

Potential causes:
 - A typo in the package name
 - The package is not available in a stable-enough version according to your minimum-stability setting
   see <https://groups.google.com/d/topic/composer-dev/_g3ASeIFlrc/discussion> for more details.

Read <http://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.

为什么我收到错误？我应该将所有pear依赖项存储在我的composer.json文件中以获取HTTP_Request2扩展吗？

附：如果我运行php composer.phar安装

"pear-pear/Archive_Tar": "*","pear-pear/Console_Getopt": "*","pear-pear/Structures_Graph": "*","pear-pear/XML_Util": "*","pear-pear/PEAR": "*","pear-pear/Net_URL2": "*"

然后添加一个字符串：“pear-pear / HTTP_Request2”：“2.2.1”并运行php composer.phar更新 – 一切都像魔术一样！但我不认为这是正确的方法.