最近在做一个 p2p 应用，有一个需求是想根据 peer 的物理距离选择最佳路由，貌似 ip 和距离没什么太直接的关系，搜索了一圈提供这种服务的大多是在线的 rpc ，又慢又有次数和频率限制，更过分的是还有收费的，哎！

苦恼了一下午终于发现了救星 《geoip2-golang》 ，他们维护了一套ip地址库并且提供了模糊的坐标信息，经过一番简单的封装，可以在 golang 程序中非常容易的使用这些信息，我已经在生产环境中使用了这个库，迫不及待分享给有需要的伙伴们。

go-geoip2-db

原码（求星）：https://github.com/cc14514/go-geoip2-db

安装

go get https://github.com/cc14514/go-geoip2-db

使用

package geoip2db

import (
    "encoding/json"
    "fmt"
    "net"
    "testing"
)

func TestNewGeoipDbByStatik(t *testing.T) {
    db, _ := NewGeoipDbByStatik()
    defer db.Close()
    record, _ := db.City(net.ParseIP("115.35.95.90"))
    fmt.Printf("Portuguese (BR) city name: %v\n", record.City.Names["pt-BR"])
    fmt.Printf("English subdivision name: %v\n", record.Subdivisions[0].Names["en"])
    fmt.Printf("Russian country name: %v\n", record.Country.Names["ru"])
    fmt.Printf("ISO country code: %v\n", record.Country.IsoCode)
    fmt.Printf("Time zone: %v\n", record.Location.TimeZone)
    fmt.Printf("Coordinates: %v, %v\n", record.Location.Latitude, record.Location.Longitude)

}

上面单元测试中得到的 record 结构如下，包含了你想要的全部信息

{
  "City": {
    "GeoNameID": 0,
    "Names": null
  },
  "Continent": {
    "Code": "AS",
    "GeoNameID": 6255147,
    "Names": {
      "de": "Asien",
      "en": "Asia",
      "es": "Asia",
      "fr": "Asie",
      "ja": "アジア",
      "pt-BR": "Ásia",
      "ru": "Азия",
      "zh-CN": "亚洲"
    }
  },
  "Country": {
    "GeoNameID": 1814991,
    "IsInEuropeanUnion": false,
    "IsoCode": "CN",
    "Names": {
      "de": "China",
      "en": "China",
      "es": "China",
      "fr": "Chine",
      "ja": "中国",
      "pt-BR": "China",
      "ru": "Китай",
      "zh-CN": "中国"
    }
  },
  "Location": {
    "AccuracyRadius": 50,
    "Latitude": 39.9289,
    "Longitude": 116.3883,
    "MetroCode": 0,
    "TimeZone": "Asia/Shanghai"
  },
  "Postal": {
    "Code": ""
  },
  "RegisteredCountry": {
    "GeoNameID": 1814991,
    "IsInEuropeanUnion": false,
    "IsoCode": "CN",
    "Names": {
      "de": "China",
      "en": "China",
      "es": "China",
      "fr": "Chine",
      "ja": "中国",
      "pt-BR": "China",
      "ru": "Китай",
      "zh-CN": "中国"
    }
  },
  "RepresentedCountry": {
    "GeoNameID": 0,
    "IsInEuropeanUnion": false,
    "IsoCode": "",
    "Names": null,
    "Type": ""
  },
  "Subdivisions": [
    {
      "GeoNameID": 2038349,
      "IsoCode": "BJ",
      "Names": {
        "en": "Beijing",
        "fr": "Municipalité de Pékin",
        "zh-CN": "北京市"
      }
    }
  ],
  "Traits": {
    "IsAnonymousProxy": false,
    "IsSatelliteProvider": false
  }
}