GeoIP是MaxMind公司推出的一款可以查询IP地址对应详细信息的工具（包括国家城市邮编等，邮编中国的不一定有），其实是一个.mmdb .CSV的数据库文件，有免费版和付费版，信息精度不一样，网上还有一种简单的.dat文件的方法，但是只能查英文（看文件大小就知道少），所以想要很好的使用这个工具还是正儿八经的用composer安装吧。
URL：http://maxmind.github.io/GeoIP2-php/
另外提一句，.dat文件的那个弄好了之后可以做为php扩展使用，直接调用相关的函数即可。
先安装composer（不多提了），然后官方用的是这条命令：
php composer.phar require geoip2/geoip2:~2.0//composer嘛，凡事先更新
$ sudo composer self-update
[sudo] password for tianyi:
Updating to version 1.4.1 (stable channel).
Downloading: 100%
Use composer self-update --rollback to return to version 1.3.2
//请忽略目录，composer设置全局了之后哪里都能用
$ composer require
You are running composer with xdebug enabled. This has a major impact on runtime performance. See https://getcomposer.org/xdebug
Search for a package: geoip2 //这里输入geoip2
Found 15 packages matching geoip2
[0] geoip2/geoip2
[1] bonvga/geoip2
[2] gpslab/geoip2
[3] tobai/magento2-geo-ip2
[4] overals/yii2-geoip2
[5] bobey/geoip2-geolite2-composer
[6] acidreign/laravel-geoip2
[7] phirational/laravel-geoip2
[8] marketo/silverstripe-regional-maxmind-geoip2
[9] maxmind-db/reader
[10] cravler/maxmind-geoip-bundle
[11] mi-la01/kt_maxmind_geoip
[12] lysenkobv/yii2-geoip
[13] whitworf/geoip2-bundle
[14] faustbrian/laravel-geoip2
//选第一个，当然这两条命令你也可以一起打
Enter package # to add, or the complete package name if it is not listed: 0
//选2.0版本或别的，注意，不填版本号直接enter的可能会卡在那没反应
Enter the version constraint to require (or leave blank to use the latest version): ~2.0
Search for a package:
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Package operations: 4 installs, 0 updates, 0 removals
- Installing composer/ca-bundle (1.0.7): Downloading (100%)
- Installing maxmind/web-service-common (v0.3.1): Downloading (100%)
- Installing maxmind-db/reader (v1.1.3): Downloading (100%)
- Installing geoip2/geoip2 (v2.4.5): Downloading (100%)
composer/ca-bundle suggests installing symfony/process (This is necessary to reliably check whether openssl_x509_parse is vulnerable on older php versions, but can be ignored on PHP 5.5.6+)
maxmind-db/reader suggests installing ext-maxminddb (A C-based database decoder that provides significantly faster lookups)
Writing lock file
Generating autoload files
//安装完成
