Develop Reference

How to Retrieve two or more json from multiple Url in MainActivity class Android

I've made a GetJSONTask class which extend AsynkTaskClass. In the onPostExecute method I get the result if I pass single URL in onCreate. like
newCustomAsync().execute("http://abcd.com/fetch/Service1.svc/GetStates?"+
"CCode=" +country+ "");
I want to call multiple URL and retrieve multiple JSON in different variables.
private class CustomAsync extends AsyncTask<String, Void, String> {
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected String doInBackground(String... URL) {
HttpClient Client = new DefaultHttpClient();
try{
String SetServerString = "";
HttpGet httpget = new HttpGet(URL[0]);
ResponseHandler<String> responseHandler =
new BasicResponseHandler();
SetServerString = Client.execute(httpget, responseHandler);
JSONArray myListsAll= new JSONArray(SetServerString);
for(int i=0;i<myListsAll.length();i++){
JSONObject jsonobject= (JSONObject) myListsAll.get(i);
String states = jsonobject.optString("states");
}
return SetServerString;
}catch(Exception e){}
return null;
}
protected void onPostExecute(String result) {
super.onPostExecute(result);
JSONArray myListsAll = null;
try {
myListsAll = new JSONArray(result);
} catch (JSONException e) {
e.printStackTrace();
}
JSONObject jsonobject= null;
try {
jsonobject = (JSONObject) myListsAll.get(0);
} catch (JSONException e) {
e.printStackTrace();
}
String msg =jsonobject.optString("states");
}
}

call all the url's in your doInbackground() and get the result. For passing multiple results to your onPostExecute(), use a wrapper class, you've to pass the object of the wrapper class.
public class CustomAsync extends AsyncTask<String, Integer, Wrapper> {
#Override
protected Wrapper doInBackground(String... params) {
String url1 = params[0];
String url2 = params[1]
Wrapper wrapper = new Wrapper();
wrapper.result1 = Get(url1);
wrapper.result2 = Get(url2);
return wrapper;
}
#Override
protected void onPostExecute(Wrapper wrapper) {
String result1 = wrapper.result1;
String result2 = wrapper.result2;
// Do your operation
}
public class Wrapper {
public String result1;
public String result2;
}
}
define Get() as separate function. Code is more clean that way
public static synchronized String Get(String url){
HttpClient Client = new DefaultHttpClient();
try{
String SetServerString = "";
HttpGet httpget = new HttpGet(url);
ResponseHandler<String> responseHandler =
new BasicResponseHandler();
SetServerString = Client.execute(httpget, responseHandler);
JSONArray myListsAll= new JSONArray(SetServerString);
for(int i=0;i<myListsAll.length();i++){
JSONObject jsonobject= (JSONObject) myListsAll.get(i);
String states = jsonobject.optString("states");
}
return SetServerString;
}catch(Exception e){}
return null;
}

Nullpoint exception even after getting data from json response

I'm trying to get data by calling webservices, for that I'm using a Async task class. As I have shon in the screen shot I'm getting json response successfully. But it crashes in listener.onTaskCompletedObject(responseJson); inside the onPostExecute().
Can anyone spot the reason wht this is not working for me.
Activity.java
new AddressAsyncTask(getBaseContext(), new OnTaskCompletedObject() {
#Override
public void onTaskCompletedObject(JSONObject responseJson) {
Constants.dataAddress = responseJson.toString();
loaddata();
}
}).execute(email);
OnTaskCompletedObject.java
public interface OnTaskCompletedObject {
void onTaskCompletedObject(JSONObject responseJson);
}
AddressAsyncTask.java
public class AddressAsyncTask extends AsyncTask<String, Integer, JSONObject> {
private OnTaskCompletedObject listener;
private JSONObject responseJson = null;
private Context contxt;
private Activity activity;
String email;
public AddressAsyncTask(Context context, OnTaskCompletedObject onTaskCompletedObject) {
this.contxt = context;
}
// async task to accept string array from context array
#Override
protected JSONObject doInBackground(String... params) {
String path = null;
String response = null;
HashMap<String, String> request = null;
JSONObject requestJson = null;
DefaultHttpClient httpClient = null;
HttpPost httpPost = null;
StringEntity requestString = null;
ResponseHandler<String> responseHandler = null;
// get the email and password
Log.i("Email", params[0]);
try {
path = "http://xxxxxxxxxxxxxxxxx/MemberDetails";
new URL(path);
} catch (MalformedURLException e) {
e.printStackTrace();
}
try {
// set the API request
request = new HashMap<String, String>();
request.put(new String("Email"), params[0]);
request.entrySet().iterator();
// Store locations in JSON
requestJson = new JSONObject(request);
httpClient = new DefaultHttpClient();
httpPost = new HttpPost(path);
requestString = new StringEntity(requestJson.toString());
// sets the post request as the resulting string
httpPost.setEntity(requestString);
httpPost.setHeader("Content-type", "application/json");
// Handles the response
responseHandler = new BasicResponseHandler();
response = httpClient.execute(httpPost, responseHandler);
responseJson = new JSONObject(response);
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
try {
responseJson = new JSONObject(response);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
return responseJson;
}
#Override
protected void onPostExecute(JSONObject result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
listener.onTaskCompletedObject(responseJson);
}
}
Screenshot of the exception
Screenshot of the jsonresponse

NullPointerException exception even after getting data from json
response
Because listener is null.
Initialize listener as :
public AddressAsyncTask(Context context, OnTaskCompletedObject listener) {
this.contxt = context;
this.listener=objListener;
}

Try changing
listener.onTaskCompletedObject(responseJson);
to
listener.onTaskCompletedObject(result);

You have forgotten to initialize your listener in the asyn task constructor.

You have forgotten to initialize your listener in AddressAsyncTask constructor.
public AddressAsyncTask(Context context, OnTaskCompletedObject onTaskCompletedObject) {
this.contxt = context;
this.listener=onTaskCompletedObject;
}

Show data from world weather online api

I am developing weather application by using world weather online API
for android.How i show data in application? data is showing in logcat.Following is my code.
MainActivity.java
public class MainActivity extends ListActivity {
private ProgressDialog pDialog;
// URL to get contacts JSON
private static String url = "http://api.worldweatheronline.com/free/v1/weather.ashx?q=";
// JSON Node names
private static final String TAG_DATA = "data";
private static final String TAG_NAME = "name";
// contacts JSONArray
JSONArray data = null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> dataList;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
dataList = new ArrayList<HashMap<String, String>>();
ListView lv = getListView();
new GetContacts().execute();
}
/**
* Async task class to get json by making HTTP call
* */
private class GetContacts extends AsyncTask<Void, Void, Void> {
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
#Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting JSON Array node
data = jsonObj.getJSONArray(TAG_DATA);
// looping through All Contacts
for (int i = 0; i < data.length(); i++) {
JSONObject c = data.getJSONObject(i);
// tmp hashmap for single contact
HashMap<String, String> contact = new HashMap<String, String>();
// adding each child node to HashMap key => value
// adding contact to contact list
dataList.add(contact);
}
} catch (JSONException e) {
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
#Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(MainActivity.this,
dataList, R.layout.list_item, new String[] { TAG_NAME }, new int[] {
R.id.name });
setListAdapter(adapter);
}
}
}
ServiceHandler.java
public class ServiceHandler {
static String response = null;
public final static int GET = 1;
public final static int POST = 2;
public ServiceHandler() {
}
/**
* Making service call
* #url - url to make request
* #method - http request method
* */
public String makeServiceCall(String url, int method) {
return this.makeServiceCall(url, method, null);
}
/**
* Making service call
* #url - url to make request
* #method - http request method
* #params - http request params
* */
public String makeServiceCall(String url, int method,
List<NameValuePair> params) {
try {
// http client
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpEntity httpEntity = null;
HttpResponse httpResponse = null;
// Checking http request method type
if (method == POST) {
HttpPost httpPost = new HttpPost(url);
// adding post params
if (params != null) {
httpPost.setEntity(new UrlEncodedFormEntity(params));
}
httpResponse = httpClient.execute(httpPost);
} else if (method == GET) {
// appending params to url
if (params != null) {
String paramString = URLEncodedUtils
.format(params, "utf-8");
url += "?" + paramString;
}
HttpGet httpGet = new HttpGet(url);
httpResponse = httpClient.execute(httpGet);
}
httpEntity = httpResponse.getEntity();
response = EntityUtils.toString(httpEntity);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return response;
}
}

First of all, this format will refer to the V1 free version. World Weather Online has released v2, which is superior. I was in the process of updating and saw this question sitting out there so I'll answer based off of what I had that did work.
You are on the right track to use the AsyncTask, here is my call to AsyncTask. You should know I use my "DataPoint" class to simply contain the data from WWO that I need to use. Based on your question, you can show the data that I will put in the DataPoint object in anyway you see fit on the screen, since at the end of the queryWeatherService(), you will end up with a parsed set of data.
//Some call to query the weather, which executes the AsyncTask
private DataPoint queryWeatherService()
{
// This method will retrieve the data from the weather service
DataPoint newDataPoint = new DataPoint();
if (!waiting)
{
try{
newDataPoint = new WeatherServiceClass().execute(
String.valueOf(getlatitude()), //Not shown here: pass in some String of a float value of of your lat coordinate.
String.valueOf(getlongitude())) //Not shown here: pass in some String of a float value of of your long coordinate.
.get();
} catch (InterruptedException | ExecutionException e)
{
e.printStackTrace();
}
}
return newDataPoint;
// Documentation:
// https://developer.worldweatheronline.com/page/documentation
}
The WeatherServiceClass that extends the AsyncTask
public class WeatherServiceClass extends AsyncTask<String, String, DataPoint> {
private String latitude;
private String longitude;
public WeatherServiceClass() {
}
#Override
protected DataPoint doInBackground(String... params) {
DataPoint dp = new DataPoint();
JSONWeatherParser jparser = new JSONWeatherParser();
latitude = params[0];
longitude = params[1];
String data = ((new WeatherHttpClient().getWeatherData(latitude, longitude)));
try {
dp = jparser.getWeather(data);
} catch (JSONException e) {
e.printStackTrace();
}
return dp;
//Reference:
// http://www.javacodegeeks.com/2013/06/android-build-real-weather-app-json-http-and-openweathermap.html
}
}
Here is the WeatherHttpClient class:
public class WeatherHttpClient {
private static String BASE_URL = "http://api.worldweatheronline.com/free/v1/weather.ashx?q=";
private static String BASE_URL_PT2 = "&format=json&num_of_days=5&date=today&key=[ENTER YOUR KEY HERE, I'M NOT GIVING YOU MINE]";
public String getWeatherData(String latitude, String longitude){
HttpURLConnection con = null;
InputStream is=null;
try{
con = (HttpURLConnection)(new URL(BASE_URL + latitude+","+longitude+BASE_URL_PT2)).openConnection();
con.setRequestMethod("GET");
con.setDoInput(true);
con.setDoOutput(true);
con.connect();
//Reading the response
StringBuffer buffer = new StringBuffer();
is = con.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String line = null;
while ((line=br.readLine()) != null)
buffer.append(line + "\r\n");
is.close();
con.disconnect();
return buffer.toString();
}
catch(Throwable t) {
t.printStackTrace();
}
finally {
try { is.close();} catch(Throwable t){}
try { con.disconnect();} catch(Throwable t){}
}
return null;
}
Finally, here is my JSONWeatherParser:
public class JSONWeatherParser {
public JSONWeatherParser() {
}
public DataPoint getWeather(String data) throws JSONException {
DataPoint dp = new DataPoint();
Weather weather = new Weather(); //This is just a class that has a bunch of strings in it for the weather info.
JSONObject jObj = new JSONObject(data);
//Parsing JSON data
JSONObject dObj = jObj.getJSONObject("data");
JSONArray cArr = dObj.getJSONArray("current_condition");
JSONObject JSONCurrent = cArr.getJSONObject(0);
weather.setCurrent_temp(getString("temp_F",JSONCurrent));
weather.setHour(getString("observation_time",JSONCurrent));
JSONArray jArr = dObj.getJSONArray("weather");
JSONObject JSONWeather = jArr.getJSONObject(0);
JSONArray jArrIcon = JSONWeather.getJSONArray("weatherIconUrl");
JSONObject JSONIcon = jArrIcon.getJSONObject(0);
weather.setDate(getString("date",JSONWeather));
weather.setPrecipmm(getString("precipMM",JSONWeather));
weather.setTempMaxc(getString("tempMaxC",JSONWeather));
weather.setTempMaxf(getString("tempMaxF",JSONWeather));
weather.setTempMinf(getString("tempMinF",JSONWeather));
weather.setTempMinc(getString("tempMinC",JSONWeather));
weather.setWeatherCode(getString("weatherCode",JSONWeather));
weather.setWeatherIconURL(getString("value",JSONIcon));
weather.setWinddir16point(getString("winddir16Point",JSONWeather));
weather.setWinddirDegree(getString("winddirDegree",JSONWeather));
weather.setWindspeedKmph(getString("windspeedKmph",JSONWeather));
weather.setWindspeedMiles(getString("windspeedMiles",JSONWeather));
dp.setWeather(weather); //assigns and converts the relevant weather strings to DataPoint
// For details of these operations and how each works go here:
// http://www.javacodegeeks.com/2013/06/android-build-real-weather-app-json-http-and-openweathermap.html
return dp;
}
private static String getString(String tagName, JSONObject jObj)
throws JSONException {
return jObj.getString(tagName);
}
}

Resuse of Async task code in my various file

I want to create an class file for Async task operation and from creating the object of that class file i want to access these method of async task with no of different class files with different parameters.
Methods of Async task include:-
OnPreExecute()-Want to start progress dialog same for each class.
doInbackground()-Want to perform background operation(like getting data from server) means passing parameter different for each class.
onPostExecute()-Dismiss the progress dialog and update the UI differnt for each class.
Now I'm writing the async task in my every class as inner class like the following:-
class loaddata extends AsyncTask<String, String, String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(AddNewLineitem.this);
pDialog.setMessage("Loading Data. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.setOnCancelListener(new OnCancelListener() {
#Override
public void onCancel(DialogInterface dialog) {
}
});
pDialog.show();
}
#Override
protected String doInBackground(String... params) {
try {
List<NameValuePair> params1 = new ArrayList<NameValuePair>();
JSONObject json = jparser.makeHttpRequest(url_foralldropdowns,
"GET", params1);
compoment = json.getJSONArray(COMPONENT_CODE);
for (int i = 1; i < compoment.length(); i++) {
JSONObject c = compoment.getJSONObject(i);
String code = c.getString(CODE);
list_compoment.add(code);
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
protected void onPostExecute(String file_url) {
loadSpinnerData();
pDialog.dismiss();
}
}
And JSON parser class is as follows:-
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
// function get json from url
// by making HTTP POST or GET mehtod
public JSONObject makeHttpRequest(String url, String method,
List<NameValuePair> params) {
// Making HTTP request
try {
// check for request method
if (method == "POST") {
// request method is POST
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.setEntity(new UrlEncodedFormEntity(params));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} else if (method == "GET") {
// request method is GET
DefaultHttpClient httpClient = new DefaultHttpClient();
String paramString = URLEncodedUtils.format(params, "utf-8");
url += "?" + paramString;
HttpGet httpGet = new HttpGet(url);
HttpResponse httpResponse = httpClient.execute(httpGet);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
And in oncreate() I call this and it works fine:-
new loaddata().execute();

We can reuse Aysntask with different parameters. For this
1.Create an Interface so that we can reuse,pass and receive parameters
public interface BackgroundListener {
public Object[] startBackgroundWork(Object... objs);
public void endBackgroundWork(Object... objs);
public void beforeBackgroundWork();
}
2.Create a Class Extending Asyntask
BackgroundHandler.java
import android.os.AsyncTask;
public class BackgroundHandler extends AsyncTask<Object, Object[], Object[]>{
BackgroundListener backgroundListener;
public void setBackgroundListener(BackgroundListener aBackgroundListener)
{
this.backgroundListener = aBackgroundListener;
}
#Override
protected void onPreExecute() {
backgroundListener.beforeBackgroundWork();
}
#Override
protected Object[] doInBackground(Object... objs) {
return backgroundListener.startBackgroundWork(objs);
}
#Override
protected void onPostExecute(Object result[]) {
backgroundListener.endBackgroundWork(result);
}
}
Using in Activity
A.java
Class A extends Activity implements BackgroundListener
{
...onCreate()
{
BackgroundHandler backgroundHandler = new BackgroundHandler()
backgroundHandler.setBackgroundListner(this);
backgroundHandler.execute(new Object[]{url1});//pass any number of parameters of any object type
// show loading bar
}
public void beforeBackgroundWork()
{
pDialog = new ProgressDialog(A.this);
pDialog.setMessage("Loading Data. Please wait...");
pDialog.setIndeterminate(false);
.....
}
public Object[] startBackgroundWork(Object... objs)
{
// access and type convert the passed parameters like objs[0], objs[1]
//.... some time consuming stuff
//.... some time consuming stuff
String url_foralldropdowns = objs[0].toString();
List<NameValuePair> params1 = new ArrayList<NameValuePair>();
JSONObject json = jparser.makeHttpRequest(url_foralldropdowns,
"GET", params1);
JSONArray compoment = json.getJSONArray(COMPONENT_CODE);
//Create new list_compoment here instead of global declaration
for (int i = 1; i < compoment.length(); i++) {
JSONObject c = compoment.getJSONObject(i);
String code = c.getString(CODE);
list_compoment.add(code);
}
retrun new Object[]{list_compoment};
}
public void endBackgroundWork(Object ...obj)
{
pDialog.dismiss();// hide loading bar
//access resultant parameters like objs[0], objs[1]
//user list_component will be in obj[0]
}
}
Similarly we can reuse in B.java
Class B extends Activity implements BackgroundListener
{
...
....
public void beforeBackgroundWork()
{
pDialog = new ProgressDialog(B.this);
pDialog.setMessage("Loading Data. Please wait...");
pDialog.setIndeterminate(false);
.....
}
public Object[] startBackgroundWork(Object... objs)
{
// access and type convert the passed parameters like objs[0], objs[1]
//.... some time consuming stuff
//.... some time consuming stuff
String url2 = objs[0].toString();
List<NameValuePair> params1 = new ArrayList<NameValuePair>();
JSONObject json = jparser.makeHttpRequest(url2,
"GET", params1);
JSONArray compoment = json.getJSONArray(COMPONENT_CODE);
//Create new list_compoment here instead of global declaration
for (int i = 1; i < compoment.length(); i++) {
JSONObject c = compoment.getJSONObject(i);
String code = c.getString(CODE);
list_compoment.add(code);
}
retrun new Object[]{list_compoment};
}
public void endBackgroundWork(Object ...obj)
{
pDialog.dismiss();
.....
//user list_component will be in obj[0]
}
}

Asyntask is just a class like others. Apart from the main inhertited methods of AsyncTask you can create your own methods, constructor etc. So just create a separate class in separate file. pass the context as parameter of the constructor. you can pass other values also to define the tasks.
class Loaddata extends AsyncTask<String, String, String> {
public Loaddata( pass the params){
... set the params
}
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog.setMessage("Loading Data. Please wait...");
pDialog.show();
}
protected void onPostExecute() {
// pDialog.dismiss();
}
#Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub
return null;
}
}

android http post asynctask

Please can anyone tell me how to make an http post to work in the background with AsyncTask and how to pass the parameters to the AsyncTask? All the examples that I found were not clear enough for me and they were about downloading a file.
I'm running this code in my main activity and my problem is when the code sends the info to the server the app slows down as if it is frozen for 2 to 3 sec's then it continues to work fine until the next send. This http post sends four variables to the server (book, libadd, and time) the fourth is fixed (name)
Thanks in advance
public void SticketFunction(double book, double libadd, long time){
Log.v("log_tag", "%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% SticketFunction()");
//HttpClient
HttpClient nnSticket = new DefaultHttpClient();
//Response handler
ResponseHandler<String> res = new BasicResponseHandler();
HttpPost postMethod = new HttpPost("http://www.books-something.com");
try {
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(5);
nameValuePairs.add(new BasicNameValuePair("book", book+""));
nameValuePairs.add(new BasicNameValuePair("libAss", libass+""));
nameValuePairs.add(new BasicNameValuePair("Time", time+""));
nameValuePairs.add(new BasicNameValuePair("name", "jack"));
//Encode and set entity
postMethod.setEntity(new UrlEncodedFormEntity(nameValuePairs, HTTP.UTF_8));
//Execute
//manSticket.execute(postMethod);
String response =Sticket.execute(postMethod, res).replaceAll("<(.|\n)*?>","");
if (response.equals("Done")){
//Log.v("log_tag", "!!!!!!!!!!!!!!!!!! SticketFunction got a DONE!");
}
else Log.v("log_tag", "!!!!!!!?????????? SticketFunction Bad or no response: " + response);
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
//Log.v("log_tag", "???????????????????? SticketFunction Client Exception");
} catch (IOException e) {
// TODO Auto-generated catch block
//Log.v("log_tag", "???????????????????? IO Exception");
}
}
}

At first,
You put a class like following:
public class AsyncHttpPost extends AsyncTask<String, String, String> {
interface Listener {
void onResult(String result);
}
private Listener mListener;
private HashMap<String, String> mData = null;// post data
/**
* constructor
*/
public AsyncHttpPost(HashMap<String, String> data) {
mData = data;
}
public void setListener(Listener listener) {
mListener = listener;
}
/**
* background
*/
#Override
protected String doInBackground(String... params) {
byte[] result = null;
String str = "";
HttpClient client = new DefaultHttpClient();
HttpPost post = new HttpPost(params[0]);// in this case, params[0] is URL
try {
// set up post data
ArrayList<NameValuePair> nameValuePair = new ArrayList<NameValuePair>();
Iterator<String> it = mData.keySet().iterator();
while (it.hasNext()) {
String key = it.next();
nameValuePair.add(new BasicNameValuePair(key, mData.get(key)));
}
post.setEntity(new UrlEncodedFormEntity(nameValuePair, "UTF-8"));
HttpResponse response = client.execute(post);
StatusLine statusLine = response.getStatusLine();
if(statusLine.getStatusCode() == HttpURLConnection.HTTP_OK){
result = EntityUtils.toByteArray(response.getEntity());
str = new String(result, "UTF-8");
}
}
catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
catch (Exception e) {
}
return str;
}
/**
* on getting result
*/
#Override
protected void onPostExecute(String result) {
// something...
if (mListener != null) {
mListener.onResult(result)
}
}
}
Now.
You just write some lines like following:
HashMap<String, String> data = new HashMap<String, String>();
data.put("key1", "value1");
data.put("key2", "value2");
AsyncHttpPost asyncHttpPost = new AsyncHttpPost(data);
asyncHttpPost.setListener(new AsyncHttpPost.Listener(){
#Override
public void onResult(String result) {
// do something, using return value from network
}
});
asyncHttpPost.execute("http://example.com");

First i would not recommend do a Http request in a AsyncTask, you better try a Service instead. Going back to the issue on how to pass parameter into an AsyncTask when you declared it you can defined each Object class of the AsyncTask like this.
public AsyncTask <Params,Progress,Result> {
}
so in your task you should go like this
public MyTask extends<String,Void,Void>{
public Void doInBackground(String... params){//those Params are String because it's declared like that
}
}
To use it, it's quite simple
new MyTask().execute("param1","param2","param3")