Question

I am generating a list of entities from my app’s datastore on Google app engine and what I am trying to do is pass that list to an Android client.

I have this in my GAE servlet to generate the list:

<code>
DatastoreService datastore = DatastoreServiceFactory.getDatastoreService();
Query query = new Query("ClimbingArea");
List<Entity> result = datastore.prepare(query).asList(FetchOptions.Builder.withDefaults());
</code>

How do I need to go about implementing something in my android app to retrieve this list?

Answer 1

You need to serialize your entities and let your Android client deserialize them. You could use any format you want but JSON, XML and ProtBuff are the most popular. For JSON you would have something like this for a single entity. For a list, you would use a JSONArray and add your entities to the array:

JSONObject jsonObj = new JSONObject();
jsonObj.put("field1", climbingArea.getField1());
jsonObj.put("field2", climbingArea.getField2());

resp.setCharacterEncoding("UTF-8");
resp.setContentType("application/x-javascript");

PrintWriter out = resp.getWriter();
out.write(jsonObj.toString());
out.flush();
out.close();