如何将Java对象转换为GeoJSON(d3图形所需)

Question

我想将java List对象转换为D3 GeoJSON.是否有任何java api可用于帮助将java对象转换为GeoJSON对象.我想在d3中显示图形.任何人都可以帮我解决这个问题吗？

Answer 1

GeoJSON非常简单; 一般的JSON库应该就是您所需要的.以下是使用json.org代码(http://json.org/java/)构建Points列表的方法:

    JSONObject featureCollection = new JSONObject();
    try {
        featureCollection.put("type", "featureCollection");
        JSONArray featureList = new JSONArray();
        // iterate through your list
        for (ListElement obj : list) {
            // {"geometry": {"type": "Point", "coordinates": [-94.149, 36.33]}
            JSONObject point = new JSONObject();
            point.put("type", "Point");
            // construct a JSONArray from a string; can also use an array or list
            JSONArray coord = new JSONArray("["+obj.getLon()+","+obj.getLat()+"]");
            point.put("coordinates", coord);
            JSONObject feature = new JSONObject();
            feature.put("geometry", point);
            featureList.put(feature);
            featureCollection.put("features", featureList);
        }
    } catch (JSONException e) {
        Log.error("can't save json object: "+e.toString());
    }
    // output the result
    System.out.println("featureCollection="+featureCollection.toString());

这将输出如下内容:

{
"features": [
    {
        "geometry": {
            "coordinates": [
                -94.149, 
                36.33
            ], 
            "type": "Point"
        }
    }
], 
"type": "featureCollection"
}