整理下资料：
需要做准备工作：
1、 一个全能地图下载（https://blog.csdn.net/qq_41619796/article/details/90241491），可以获取边界坐标
2、获取文件的网站 http://geojson.io
3、GoogleEarthProPortable.exe文件，或者arcgis,又或者udig，用来查看最终生成文件
步骤：以县级为案例
第一：打开全能地图下载器
1、找县，2、打开左上角文件 ==》导出边界坐标，得到一个txt文件，里面有坐标数据
第二：把txt边界数据改变为geojson文件：
{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"properties": {},
"geometry": {
"type": "Polygon",
"coordinates": [
[//从这里开始，把你txt中得到的坐标数据，把下面的替换了
[112.399030,22.775490],
[112.391630,22.782920],
[112.390420,22.796070],
[112.383750,22.801780],
[112.367500,22.794760],
[112.361760,22.797720],
[112.319250,22.794060],
[112.319700,22.798450],
[112.327170,22.801680],
[112.329700,22.807390],
[112.342210,22.814480],
[112.328030,22.829690],
[112.320570,22.829690],
[112.318580,22.839200],
[112.296840,22.830590],
[112.289390,22.830650],
[112.285480,22.834570],
[112.280710,22.829580],
[112.267720,22.830130],
[112.265520,22.840970],
[112.255470,22.847570],
[112.226430,22.836550],
[112.222110,22.838530],
[112.219530,22.825250],
[112.194260,22.808240],
[112.188510,22.806860],
[112.180730,22.810200],
[112.164170,22.789040],
[112.142390,22.792620],
[112.131860,22.790450],
[112.124570,22.778760],
[112.107790,22.772610],
[112.098200,22.751400],
[112.090550,22.749180],
[112.083300,22.738890],
[112.076090,22.736940],
[112.075620,22.721080],
[112.060560,22.705960],
[112.050210,22.688190],
[112.049950,22.674780],
[112.058340,22.667270],
[112.049650,22.650080],
[112.032790,22.647970],
[112.028710,22.659630],
[112.016120,22.655270],
[112.010350,22.659730],
[111.984900,22.650380],
[111.972440,22.633830],
[111.974710,22.623580],
[111.982690,22.611730],
[111.994270,22.599570],
[112.006450,22.593070],
[112.000790,22.575010],
[111.991470,22.569070],
[111.984660,22.570310],
[111.977360,22.551110],
[111.994180,22.519200],
[111.996840,22.504080],
[112.014120,22.480950],
[112.036940,22.473130],
[112.055550,22.457200],
[112.070290,22.452270],
[112.089700,22.424110],
[112.134350,22.412850],
[112.148550,22.420340],
[112.152240,22.418810],
[112.165710,22.407610],
[112.164040,22.401100],
[112.167300,22.395410],
[112.176900,22.392850],
[112.183620,22.384530],
[112.190570,22.381920],
[112.195750,22.403470],
[112.204980,22.405380],
[112.203990,22.413770],
[112.223340,22.418680],
[112.233010,22.414090],
[112.249530,22.414680],
[112.250590,22.420190],
[112.242830,22.436760],
[112.269120,22.486460],
[112.262100,22.495640],
[112.264410,22.509180],
[112.295370,22.519510],
[112.307110,22.519870],
[112.312560,22.537110],
[112.309750,22.550640],
[112.314750,22.560810],
[112.326340,22.561610],
[112.349540,22.550450],
[112.379940,22.559270],
[112.385920,22.571520],
[112.383290,22.597060],
[112.399040,22.602760],
[112.406390,22.624730],
[112.419800,22.626570],
[112.421510,22.631240],
[112.415400,22.641870],
[112.422940,22.655810],
[112.438630,22.657660],
[112.442880,22.627540],
[112.449530,22.615630],
[112.448610,22.607750],
[112.464360,22.604060],
[112.472360,22.589770],
[112.478830,22.590230],
[112.489700,22.597280],
[112.495140,22.595970],
[112.512220,22.606700],
[112.525380,22.610610],
[112.528190,22.616210],
[112.524770,22.628940],
[112.508700,22.646230],
[112.508570,22.658930],
[112.512070,22.661690],
[112.504090,22.665150],
[112.499030,22.676650],
[112.497900,22.692940],
[112.488000,22.699820],
[112.484520,22.709610],
[112.471700,22.717670],
[112.461320,22.714670],
[112.453890,22.720550],
[112.452590,22.705270],
[112.432780,22.675120],
[112.422260,22.677530],
[112.411190,22.688710],
[112.407920,22.695570],
[112.414600,22.708270],
[112.414440,22.716500],
[112.405000,22.727700],
[112.397110,22.767310],
[112.399030,22.775490]
]
]
}
}
]
}第三：把生成的geojson，导入 http://geojson.io
这里可以看到新兴县已经出来了，下来也可以把他转换为shp类型的文件，或者其他类型
最后用其他软件看下最终生成的文件，这样就完成了，