Android HTTP GET requests stored in JSON

March 17, 2014

In my current project, I’m currently working on making an Android client send simple HTTP GET requests for data to a web API. I finally managed to get it working using the HTTP Apache library.

Note: I un-indented the code so it would fit better on the page even though it looks a bit ugly. You might be better off copying it to your text editor to read it better.

HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://dogecoin.com/api");
HttpResponse httpresponse = null;

final Thread t = new Thread() {
    public void run() {

    Looper.prepare();
    ArrayList<NameValuePair> postParameters;

    postParameters = new ArrayList<NameValuePair>();
    postParameters.add(
        new BasicNameValuePair("key", "value"));
    postParameters.add(
        new BasicNameValuePair("double", Double.toString(123)));
    postParameters.add(
        new BasicNameValuePair("float", Float.toString(123.04)));

    try {
        httppost.setEntity(new UrlEncodedFormEntity(postParameters));
        // reset to null before making a new post if it's being reused
        httpresponse = null;
        httpresponse = httpclient.execute(httppost);
    } catch (IOException e1) {
        e1.printStackTrace();
    }

    // Checking response
    if(httpresponse!=null){

    try {

        // Get the data in the entity
        BufferedReader reader = new BufferedReader(
            new InputStreamReader(
                httpresponse.getEntity().getContent(), "UTF-8")
        );

        StringBuilder builder = new StringBuilder();
        for (String line = null; (line = reader.readLine()) != null;) {
            builder.append(line).append("\n");
        }

        JSONTokener tokener = new JSONTokener(builder.toString());
        JSONObject finaljson = new JSONObject(tokener);

        Log.v("JSON OUTPUT: ", finaljson.toString());

    } catch (IOException e) {
        e.printStackTrace();
    } catch (JSONException e) {
        e.printStackTrace();
    }

    }

    Looper.loop(); //Loop in the message queue
    
    }
};

t.start();


To explain some parts that might not seem obvious, we use new UrlEncodedFormEntity() to URL encode the name-value pairs to be http://dogecoin.com/api?key=value. The encoder handles the character conversion so you can enter it in it’s original ASCII form.

Any non-string type needs to be converted into a string in order to be encoded. This is mainly because BasicNameValuePair handles only strings.

After executing the HttpPost, if our response is going to be JSON encoded, we can loop through the response to hold within a string, and then use the JSONTokener to build a JSONObject. You ought to output the response into the logs the first few times just to verify it is correct.

Side Note: To remain consistent you could always store your GET message in JSON as well and create a getNameValueArrayList() to easily output the object. However, that solely depends on your needs.