Composer安装

Composer rquire安装插件失败

1. 建议先将Composer版本升级到最新 composer self-update
2. 执行诊断命令： 

   composer diagnose

3. 清除缓存： 

   composer clear

4. 若项目之前已通过其他源安装，则需要更新 composer.lock 文件，执行命令：

    composer update --lock

5. 配置阿里云和官方两个源，阿里云镜像站下载文件出错时再从官方源上下载：

    { "repositories": [ { "description": "阿里云镜像", "type": "composer", "url": "https://mirrors.aliyun.com/composer/", "canonical": false } ] }

6. 重试一次下载