什么是GeoJson？

GeoJSON是一种对各种地理数据结构进行编码的格式，基于json的地理空间信息数据交换格式。GeoJSON对象可以表示几何、特征或者特征集合，支持点、线、面、多点、多线、多面和几何集合。GeoJSON里的特征包含一个几何对象和其他属性，特征集合表示一系列特征。

GeoJson的构成

GeoJSON数据的构成如下，type为必须值，其包含如下类型："Point/点", "MultiPoint/多点", "LineString/线", "MultiLineString/多线", "Polygon/面", "MultiPolygon/多面", "GeometryCollection", "Feature","FeatureCollection"

{
    "type": "FeatureCollection",
    "features": [
        {
            "type": "Feature",
            "geometry": {
                "type": "Point",
                "coordinates": [
                    102.0,
                    0.5
                ]
            },
            "properties": {
                "prop0": "value0"
            }
        },
        {
            "type": "Feature",
            "geometry": {
                "type": "LineString",
                "coordinates": [
                    [
                        102.0,
                        0.0
                    ],
                    [
                        103.0,
                        1.0
                    ],
                    [
                        104.0,
                        0.0
                    ],
                    [
                        105.0,
                        1.0
                    ]
                ]
            },
            "properties": {
                "prop0": "value0",
                "prop1": 0.0
            }
        },
        {
            "type": "Feature",
            "geometry": {
                "type": "Polygon",
                "coordinates": [
                    [
                        100.0,
                        0.0
                    ],
                    [
                        101.0,
                        0.0
                    ],
                    [
                        101.0,
                        1.0
                    ],
                    [
                        100.0,
                        1.0
                    ],
                    [
                        100.0,
                        0.0
                    ]
                ]
            },
            "properties": {
                "prop0": "value0",
                "prop1": {
                    "this": "that"
                }
            }
        }
    ]
}