如何将Java对象转换为GeoJSON（d3图形需要） [英] How to Convert Java Object in to GeoJSON (Required by d3 Graph)

问题描述

我要将 java列表对象转换为 D3 GeoJSON 。
有任何java api可用，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？

I want to convert java List object into D3 GeoJSON. Is there any java api available that help to convert java object to GeoJSON object. I want to display graph in d3. Can anyone help me to solve this problem?

推荐答案

GeoJSON非常简单;一个通用的JSON库应该是你需要的。以下是使用json.org代码（ http://json.org/java/ ）构建点列表的方法： / p>

GeoJSON is very simple; a general JSON library should be all you need. Here's how you could construct a list of Points using the json.org code (http://json.org/java/):

    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：

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

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