This post covers the following topics

• Post HTTP request containing parameters to a web server
• Get HTTP post response (JSON Response)
• Parse JSON Response
• Populate Results to ListView

Steps:

1. Create a new HttpClient Class
2. Create JSON Request object
3. Send Http Request and Get Response
4. Parse JSON Response object
5. Populate to ListView

1. Create a new HttpClient Class

 
public class HttpClient {
 static URL url;
 static HttpURLConnection conn;
 static OutputStream os;
 
 static String resultString=null;
 public static String SendHttpPost(String URL, String req, Activity act) {
  try{
   url=new URL(URL);
   conn = (HttpURLConnection) url.openConnection();
   
   conn.setDoOutput(true);
   conn.setRequestMethod("POST");
   
   conn.setConnectTimeout(90000); //Connection Timeout time in mSec
   conn.setReadTimeout(90000); //Read Timeout time in mSec
      
   conn.setRequestProperty(HTTP.CONTENT_TYPE, "application/json");
   conn.setRequestProperty("Accept", "application/json");
   
   conn.setFixedLengthStreamingMode(req.getBytes().length);
   
   conn.connect(); //open
   
   long t = System.currentTimeMillis();
   os = new BufferedOutputStream(conn.getOutputStream()); //setup send
   os.write(req.getBytes());
   
   os.flush(); //clean up
   
   if (conn.getResponseCode() == HttpURLConnection.HTTP_OK){
    Log.i("HttpClient", "HTTPResponse received in [" + (System.currentTimeMillis()-t) + "ms]");
    
     //do somehthing with response
     Scanner inStream = new Scanner(conn.getInputStream());
     
     //process the stream and store it in StringBuilder
     resultString = new String();
     while(inStream.hasNextLine())
      resultString+=(inStream.nextLine());
     
     return resultString;
   }
   
   // handle issues
   if (conn.getResponseCode() == HttpURLConnection.HTTP_CLIENT_TIMEOUT){
    showMsgDialogToFinish("Alert", "Request Timed out..! Plsase Try again", "Go back", act);    
   }
   if (conn.getResponseCode() == HttpURLConnection.HTTP_SERVER_ERROR){
    showMsgDialogToGoHome("Alert", "We are sorry the service is currently unavailable..!  Please try again later.", "Go back", act);    
   }
  }catch (MalformedURLException e) {   
     } catch (SocketTimeoutException e) {      
     } catch (IOException e) {
      Methods.wscContext =null;      
      e.printStackTrace();
     }finally {  
     //clean up
     try {
    os.close();
    } catch (IOException e) {     
    e.printStackTrace();
    }     
     conn.disconnect();
   } 
  return null;
 }
}

2. Create JSON Request object

Sample JSON request: {"username":"user","password":"smething"}

JSONObject jsonReq = new JSONObject();

 try {
  jsonReq.put("username", username);
  jsonReq.put("password", pwd);
 } catch (JSONException e) {
  Log.e(TAG, "JSONException: " + e);
 }

3. Send Http Request and Get Response

public class GetResponse {
 
 static String jsonResponse = null;

 public static String getResponse(String url, Activity act){
    try {             
      String username = "user";
      String pwd = "something";
      String contentType = "application/json";
      
      JSONObject jsonReq = new JSONObject();

      try {
       jsonReq.put("username", username);
       jsonReq.put("password", pwd);
      } catch (JSONException e) {
       Log.e(TAG, "JSONException: " + e);
      }      
      
      Log.i("GetResponse",">>\n"+jsonReq+"\n");

      // Send the HttpPostRequest and receive a JSONObject in return
      jsonResponse = new String();
      jsonResponse = HttpClient.SendHttpPost( url, jsonReq, act);

    } catch (JSONException e) {
     e.printStackTrace();
    }
  return jsonResponse;
 }
}

4. Parse JSON Response object

Sample JSON Request which is return from getResponseObj method
{
 "MovieList": [{
  "Movie": "Wreck it ralph",
  
 },
 {
  "Movie": "Tangled",
  
 }]
}

JSONObject jsonResponse;
ArrayList myMovieList = new ArrayList();                    
               try {
                     
                    /* Creates a new JSONObject from the JSON string*/
                    jsonResponse = new JSONObject(strJson);
                     
                    /* Returns the value mapped by name */                    
                    JSONArray jsonMainNode = jsonResponse.getJSONArray("MovieList");
                     
                    int lengthJsonArr = jsonMainNode.length();  
 
                    for(int i=0; i < lengthJsonArr; i++) 
                    {
                        /****** Get Object for each JSON node.***********/
                        JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
                         
                        /******* Fetch node values **********/                        
                        String movie_name   = jsonChildNode.optString("Movie").toString();    
      myMovieList.add(movie_name);
     }

5. Populate to ListView
In MainActivity,

public class MainActivity extends Activity{
 ListView listView;
 @Override
 protected void onCreate(BundlesavedInstanceState){
  super.onCreate(savedInstanceState);
  setContentView(R.layout.myLayout);
  //GetListView object from xml
  listView=(ListView)findViewById(R.id.list);
  
  //use our myMovieList data
  ArrayAdapteradapter=new ArrayAdapter
  (this,android.R.layout.simple_list_item_1,android.R.id.text1,myMovieList);
  
  //Assign adapter to ListView
  
  listView.setAdapter(adapter);
  
  //ListViewItemClickListener
  
  listView.setOnItemClickListener(newOnItemClickListener(){
   @Override
   public void onItemClick(AdapterViewparent,Viewview,intposition,longid){
    //ListView Clicked item index 
    int itemPosition=position;
    
    //ListView Clicked itemvalue
    StringitemValue=(String)listView.getItemAtPosition(position);
    //ShowAlert
    Toast.makeText(getApplicationContext(),"Position :"+itemPosition+" ListItem : "+itemValue,Toast.LENGTH_LONG).show();
   }
  });
 }
}

Sample Output: