Suppose you want to send this JSON string using HTTP using Content-type: application/json
{"jsonrpc":"2.0","method":"myMethod","params":[{"first":"A","second":"B"}],"id":"0"}
What makes this different from a regular HTTP call is the presence of an attachment and the Content-type: application/json designation. Here is the POST method:
public HttpResponse doPost() throws JSONException, ClientProtocolException, IOException {
HttpClient client = new DefaultHttpClient();
JSONObject json = createMethodCall("myMethod", createMethodParams());
Log.d(LOGTAG, json.toString());
HttpResponse response = client.execute(createRequest(json));
return response;
}
I use the org.json libaries to construct my JSON object because the toString() method produces syntactically-correct JSON with no effort on my part:
public JSONObject createMethodCall(String method, JSONArray params) throws JSONException {
JSONObject json = new JSONObject();
json.put("jsonrpc", "2.0");
json.put("id", "0"); // we don't really use this so value is always zero
json.put("method", method);
json.put("params", params);
return json;
}
public JSONArray createMethodParams() throws JSONException {
JSONArray params = new JSONArray();
// Default params that appear in all method calls
params.put(new JSONObject().put("first", "A"));
params.put(new JSONObject().put("second", "B"));
// To add custom parameters, add to the return value rather than here, or this method becomes messy
return params;
}
The final trick is that HttpEntity is the Java object for MIME attachments. Therefore, attaching the JSON string as a StringEntity and declaring the content type as "application/json" is required for the server to recognize it as a valid JSON-RPC call.
public HttpPost createRequest (JSONObject json) throws UnsupportedEncodingException {
HttpPost request = new HttpPost(this.server + this.url);
StringEntity entity = new StringEntity(json.toString());
request.setEntity(entity);
request.setHeader("Accept", "application/json");
request.setHeader("Content-type", "application/json");
return request;
}
I suppose I could have gotten fancy and created a library that packages JSON-RPC more cleanly, but I chose to organize it as a collection of convenience methods. Here is the call from the parent code:
RemoteCall remote = new RemoteCall();
String response = null;
try {
response = remote.doPost();
} catch (Exception e) {
e.printStackTrace();
}
