官方的maven中央仓库在国内太慢了，速度不忍直视。好在国内有一些镜像仓库，比如阿里云，速度快很多很多。
配置阿里云maven仓库
vim ~/.m2/settings.xml
如果文件为空，添加以下内容：
<?xml version="1.0" encoding="UTF-8"?>
<settings xmlns="http://maven.apache.org/SETTINGS/1.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.0.0 http://maven.apache.org/xsd/settings-1.0.0.xsd">
<servers>
<server>
<id>nexus-snapshots</id>
<username>deployment</username>
<password>123456</password>
</server>
</servers>
<mirrors>
<mirror>
<id>alimaven</id>
<name>aliyun maven</name>
<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
<mirrorOf>central</mirrorOf>
</mirror>
</mirrors>
</settings>
如果文件有内容了，则添加镜像部分就好了：
<mirrors>
<mirror>
<id>alimaven</id>
<name>aliyun maven</name>
<url>http://maven.aliyun.com/nexus/content/groups/public/</url>
<mirrorOf>central</mirrorOf>
</mirror>
</mirrors>
