How to send POST request in JSON using HTTPClient in Android?

Question

I'm trying to figure out how to POST JSON from Android by using HTTPClient. I've been trying to figure this out for a while, I have found plenty of examples online, but I cannot get any of them to work. I believe this is because of my lack of JSON/networking knowledge in general. I know there are plenty of examples out there but could someone point me to an actual tutorial? I'm looking for a step by step process with code and explanation of why you do each step, or of what that step does. It doesn't need to be a complicated, simple will suffice.

Again, I know there are a ton of examples out there, I'm just really looking for an example with an explanation of what exactly is happening and why it is doing that way.

If someone knows about a good Android book on this, then please let me know.

Thanks again for the help @terrance, here is the code I described below

public void shNameVerParams() throws Exception{
     String path = //removed
     HashMap  params = new HashMap();

     params.put(new String("Name"), "Value"); 
     params.put(new String("Name"), "Value");

     try {
        HttpClient.SendHttpPost(path, params);
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
 }

Answer 1

In this answer I am using an example posted by Justin Grammens.

About JSON

JSON stands for JavaScript Object Notation. In JavaScript properties can be referenced both like this object1.name and like this object['name'];. The example from the article uses this bit of JSON.

The Parts
A fan object with email as a key and [email protected] as a value

{
  fan:
    {
      email : '[email protected]'
    }
}

So the object equivalent would be fan.email; or fan['email'];. Both would have the same value of '[email protected]'.

About HttpClient Request

The following is what our author used to make a HttpClient Request. I do not claim to be an expert at all this so if anyone has a better way to word some of the terminology feel free.

public static HttpResponse makeRequest(String path, Map params) throws Exception 
{
    //instantiates httpclient to make request
    DefaultHttpClient httpclient = new DefaultHttpClient();

    //url with the post data
    HttpPost httpost = new HttpPost(path);

    //convert parameters into JSON object
    JSONObject holder = getJsonObjectFromMap(params);

    //passes the results to a string builder/entity
    StringEntity se = new StringEntity(holder.toString());

    //sets the post request as the resulting string
    httpost.setEntity(se);
    //sets a request header so the page receving the request
    //will know what to do with it
    httpost.setHeader("Accept", "application/json");
    httpost.setHeader("Content-type", "application/json");

    //Handles what is returned from the page 
    ResponseHandler responseHandler = new BasicResponseHandler();
    return httpclient.execute(httpost, responseHandler);
}

Map

If you are not familiar with the Map data structure please take a look at the Java Map reference. In short, a map is similar to a dictionary or a hash.

private static JSONObject getJsonObjectFromMap(Map params) throws JSONException {

    //all the passed parameters from the post request
    //iterator used to loop through all the parameters
    //passed in the post request
    Iterator iter = params.entrySet().iterator();

    //Stores JSON
    JSONObject holder = new JSONObject();

    //using the earlier example your first entry would get email
    //and the inner while would get the value which would be '[email protected]' 
    //{ fan: { email : '[email protected]' } }

    //While there is another entry
    while (iter.hasNext()) 
    {
        //gets an entry in the params
        Map.Entry pairs = (Map.Entry)iter.next();

        //creates a key for Map
        String key = (String)pairs.getKey();

        //Create a new map
        Map m = (Map)pairs.getValue();   

        //object for storing Json
        JSONObject data = new JSONObject();

        //gets the value
        Iterator iter2 = m.entrySet().iterator();
        while (iter2.hasNext()) 
        {
            Map.Entry pairs2 = (Map.Entry)iter2.next();
            data.put((String)pairs2.getKey(), (String)pairs2.getValue());
        }

        //puts email and '[email protected]'  together in map
        holder.put(key, data);
    }
    return holder;
}

Please feel free to comment on any questions that arise about this post or if I have not made something clear or if I have not touched on something that your still confused about... etc whatever pops in your head really.

(I will take down if Justin Grammens does not approve. But if not then thanks Justin for being cool about it.)