如何用composer開發自己的php擴充包

$ composer init
  Welcome to the Composer config generator
  
This command will guide you through creating your composer.json config.
Package name (<vendor>/<name>) [administrator/self_composer]: victor/composer-self //包名称-不能大写，否则无效 
Description []: composer-self package //描述
Author [victor24680 <490319148@qq.com>, n to skip]://作者
Minimum Stability []: dev //最小稳定版本
Package Type (e.g. library, project, metapackage, composer-plugin) []: library //类型
License []: MIT
Define your dependencies.
Would you like to define your dependencies (require) interactively [yes]? n //是否定义依赖关系
Would you like to define your dev dependencies (require-dev) interactively [yes]? n
{
    "name": "victor/composer-self",
    "description": "This is a composer-send package",
    "type": "victor",
    "license": "MIT",
    "authors": [
        {
            "name": "victor24680",
            "email": "490319148@qq.com"
        }
    ],
    "minimum-stability": "dev",
    "require": {}
}
Do you confirm generation [yes]? yes

{
    "name": "victor/sendtool-package",
    "description": "sendtool package",
    "type": "victor",
    "license": "MIT",
    "authors": [
        {
            "name": "victor24680",
            "email": "490319148@qq.com"
        }
    ],
    "minimum-stability": "dev",
    "require": {
        "php": ">=5.6" //php版本要求
    },
    "autoload": {
        "psr-4": { //加载规范
            "App\\": "src/App",
            "Contract\\": "src/Contract"
        }
    }
}

$ composer install
Loading composer repositories with package information
Updating dependencies (including require-dev)
Content-Length mismatch, received 37487 bytes out of the expected 2005372
http://packagist.org could not be fully loaded, package information was loaded from the local cache and may be out of date
Nothing to install or update
Writing lock file
Generating autoload files

git init
git add .
git commit -m "初始自己的组件库"
git remote add origin https://github.com/victor24680/self-composer.git
git push origin master

$ composer require victor24680/self-composer dev-master
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Package operations: 1 install, 0 updates, 0 removals
  - Installing victor24680/self-composer (dev-master 0935c75): Cloning 0935c75eda from cache
Writing lock file
Generating autoload files
<?php
#项目根目录/index.php
include "vendor/autoload.php";
use App\CommonInfo;
use App\Zn;
$app=new CommonInfo(new Zn());
echo $app->msg(&#39;小明&#39;,&#39;隔壁老王在偷吃！！！&#39;);
//输出：【站内消息】发送给：小明|发送内容：【普通消息】隔壁老王在偷吃！！！