如何在symfony2中安装EventDispatcher

I want to install event dispatcher. I have downloaded composer and I have put this in composer.json file

"require": {
        "php": ">=5.3.3",
        "symfony/symfony": "2.1.*",
        "doctrine/orm": "2.2.*",
        "doctrine/doctrine-bundle": "dev-master",
        "twig/extensions": "dev-master",
        "symfony/assetic-bundle": "dev-master",
        "symfony/swiftmailer-bundle": "dev-master",
        "symfony/monolog-bundle": "dev-master",
        "sensio/distribution-bundle": "dev-master",
        "sensio/framework-extra-bundle": "dev-master",
        "sensio/generator-bundle": "dev-master",
        "jms/security-extra-bundle": "1.1.*",
        "jms/di-extra-bundle": "1.0.*",


    **"symfony/event-dispatcher": "dev-master"**

But I am still not able to install it.

I get this error

PHP Fatal error: Class 'Symfony\Component\ClassLoader\UniversalClassLoader' not found in /home/xxxxx/public_html/cxxxxx/Symfony/app/autoload.php

You are requiring symfony/symfony which includes the event-dispatcher. So adding it is not needed. Once composer is working, you will have access to it.

The actual problem however is that you're trying to use composer, but didn't adapt your autoload.php to use the composer autoloader.

Take a look at the Symfony Standard Edition's autoload.php. If you do things like this, you will get rid of your error.