geoCoder.getFromLocationName returns null

”The Geocoder class requires a backend service that is not included in the core android framework. The Geocoder query methods will return an empty list if there no backend service in the platform.“

这里说到了要有个backend服务，但并有说此服务要怎么得到，坛子上有人觉得要用google map api.
在下面两个链接中，也有外国朋友提到用map api!

The documentation states : The Geocoder class requires a backend service that is not included in the core android framework, how/where can I obtain such a service? 
It seems It's a bug in the emulator for 2.2 and there is a bug fix about it, for details

seehttp://code.google.com/p/android/issues/detail?id=8816 

I have found a workaround to the issue. I used the standard google api:

http://code.google.com/apis/maps/documentation/geocoding/ 

I have created a method that received a String address like "220+victoria+square" and returns a JSONObject with the response of the HTTP Call 

 

public static JSONObject getLocationInfo(String address) {

        HttpGet httpGet = new HttpGet("http://maps.google.
                + "com/maps/api/geocode/json?address=" + address
                + "ka&sensor=false");
        HttpClient client = new DefaultHttpClient();
        HttpResponse response;
        StringBuilder stringBuilder = new StringBuilder();

        try {
            response = client.execute(httpGet);
            HttpEntity entity = response.getEntity();
            InputStream stream = entity.getContent();
            int b;
            while ((b = stream.read()) != -1) {
                stringBuilder.append((char) b);
            }
        } catch (ClientProtocolException e) {
        } catch (IOException e) {
        }

        JSONObject jsonObject = new JSONObject();
        try {
            jsonObject = new JSONObject(stringBuilder.toString());
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return jsonObject;
    }

 

 

After executing this, another method converts that JSONObject into a GeoPoint. 

public static GeoPoint getGeoPoint(JSONObject jsonObject) {

        Double lon = new Double(0);
        Double lat = new Double(0);

        try {

            lon = ((JSONArray)jsonObject.get("results")).getJSONObject(0)
                .getJSONObject("geometry").getJSONObject("location")
                .getDouble("lng");

            lat = ((JSONArray)jsonObject.get("results")).getJSONObject(0)
                .getJSONObject("geometry").getJSONObject("location")
                .getDouble("lat");

        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return new GeoPoint((int) (lat * 1E6), (int) (lon * 1E6));

    }

 

 

However this solution is extremely nasty and coupled.. 
PS. you should add

<uses-library android:name="com.google.android.maps">uses-library>

 

 

to AndroidManifest.xml or application could not find GeoPoint class. 

顺便推荐篇android地图开发入门文章：

http://mobiforge.com/developing/story/using-google-maps-android