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Asynchronous task messaging with Java Servlet

I have a simple application that communicates with its Servlet server through an Async task. I have some problems understanding how messages are wrapped and how to manipulate the data structures of these messages. What I want to do is get either multiple objects or multiple heterogeneous information. My code is:

public class MyServlet extends HttpServlet {
    ArrayList<Tour> m_tours;

    @Override
    public void doGet(HttpServletRequest req, HttpServletResponse resp)
        throws IOException {
    resp.setContentType("text/plain");
    resp.getWriter().println("Please use the form to POST to this url");

    }

    @Override
    public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {

    String order = req.getParameter("order");
    resp.setContentType("text/plain");
    if (order == null) {
        resp.getWriter().println("Please enter a name");
    }

      resp.getWriter().println("yay name received");
      ArrayList<Tour> m_tours = getTours(); //returns a populated ArrayList of custom Tour objects
      resp.getWriter().print(m_tours);
}
    private void getTours(){
        //some code here
    }
}`

And my Async task class:

class ServletPostAsyncTask extends AsyncTask<Pair<Context, String>, Void, String> {
private Context context;
@Override
protected String doInBackground(Pair<Context, String>... params) {
    context = params[0].first;
    String order = params[0].second;

    String[] url = new String[3];
    url[0] = "http://192.168.169.85:8080/hello";
    url[1] = "http://10.0.2.2:8080/hello";
    url[2] = "http://192.168.1.102:8080/hello";
    HttpClient httpClient = new DefaultHttpClient(); 
    HttpPost httpPost = new HttpPost(url[2]);

    List<NameValuePair> nameValuePairs = new ArrayList<>(1);
    nameValuePairs.add(new BasicNameValuePair("order", order));
        try {
            // Add name data to request
            httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            // Execute HTTP Post Request
            HttpResponse response = httpClient.execute(httpPost);

            HttpEntity entity = response.getEntity();
            if (response.getStatusLine().getStatusCode() == 200) {
                return EntityUtils.toString(entity);
            }
                return "Error: " + response
                        .getStatusLine()
                        .getStatusCode() + " " + response
                        .getStatusLine().getReasonPhrase();
        } catch (ClientProtocolException e) {
            return e.getMessage();
        } catch (IOException e) {
            return e.getMessage();
        }
    }

@Override
protected void onPostExecute(String result) {
       String result1 = "Response: "+result;
           Toast.makeText(context, result1, Toast.LENGTH_LONG).show();
    }
}

The response message returns an ArrayList as text:

 Response: yay name received
 packagename@objectkey1
 packagename@objectkey2
 packagename@objectkey3
 ...
 packagename@objectkeyn

But instead, I want to keep it as it is, as an ArrayList. How to set up an Async task to get my m_tours ArrayList array and save it somewhere for future use? Also, how can I configure it to accept multiple objects?

* EDIT *

Gson, @orip, Async :

@Override
protected String doInBackground(Pair<Context, String>... params) {
    context = params[0].first;
    String order = params[0].second;

    String[] url = new String[3];
    url[0] = "http://192.168.169.85:8080/hello";
    url[1] = "http://10.0.2.2:8080/hello";
    url[2] = "http://192.168.1.102:8080/hello";
    // HttpPost httpPost = new HttpPost("http://semiotic-art-88319.appspot.com/hello");
    HttpClient httpClient = new DefaultHttpClient(); //127.0.0.1 - 10.201.19.153
    HttpPost httpPost = new HttpPost(url[2]);

    List<NameValuePair> nameValuePairs = new ArrayList<>(1);
    nameValuePairs.add(new BasicNameValuePair("order", order));

    try {
        // Add name data to request
        httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
        // Execute HTTP Post Request
        HttpResponse response = httpClient.execute(httpPost);
        if (response.getStatusLine().getStatusCode() == 200) {
            HttpEntity entity = response.getEntity();
            return EntityUtils.toString(entity);
        }
        return "Error: " + response
                .getStatusLine()
                .getStatusCode() + " " + response
                .getStatusLine().getReasonPhrase();
    } catch (ClientProtocolException e) {
        return e.getMessage();
    } catch (IOException e) {
        return e.getMessage();
    }
}

@Override
protected void onPostExecute(String jsonResponse) {
    Gson gson = new Gson();
    tours = (gson.fromJson(jsonResponse, Tours.class));
    Toast.makeText(context, jsonResponse, Toast.LENGTH_LONG).show();
}

:

@Override
public void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {

    String asyncMessage = req.getParameter("order");
    if(asyncMessage.equals("tours")){
        m_tours = getTours();  //ArrayList<Tour> m_tours;
        Tours tours = new Tours(m_tours);
        resp.setContentType("application/json");
        PrintWriter out = resp.getWriter();
        out.print(new Gson().toJson(tours));
        out.flush();

        resp.getWriter().print(m_tours);
    }

}

:

03-23 13:27:09.523  32387-32387/madapps.bicitourbo E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: madapps.bicitourbo, PID: 32387
com.google.gson.JsonSyntaxException: com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 692 path $
        at com.google.gson.Gson.assertFullConsumption(Gson.java:786)
        at com.google.gson.Gson.fromJson(Gson.java:776)
        at com.google.gson.Gson.fromJson(Gson.java:724)
        at com.google.gson.Gson.fromJson(Gson.java:696)
        at madapps.bicitourbo.ServletPostAsyncTask.onPostExecute(ServletPostAsyncTask.java:92)
        at madapps.bicitourbo.ServletPostAsyncTask.onPostExecute(ServletPostAsyncTask.java:36)
        at android.os.AsyncTask.finish(AsyncTask.java:632)
        at android.os.AsyncTask.access$600(AsyncTask.java:177)
        at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:149)
        at android.app.ActivityThread.main(ActivityThread.java:5257)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:515)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:609)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON at line 1 column 692 path $

:

Tour tours = (gson.fromJson(jsonResponse, Tours.class));

?

* EDIT2 * :

: Caused by: com.google.gson.stream.MalformedJsonException: Use JsonReader.setLenient(true) to accept malformed JSON , resp.getWriter().print() , @orip. !

0
1

application/json JSON (, Gson Jackson .

Android JSON, JSON Android, (), , .

, Tour :

public class Tour {
  // some simple int/string/list fields
}

, :

public class Tours {
  private List<Tour> tours;
  // ...
}

(. , Gson ):

List<Tour> listOfTours = ...;
Tours tours = new Tours(listOfTours);
response.setContentType("application/json");
PrintWriter out = response.getWriter();
out.print((new Gson()).toJson(tours));
out.flush();

:

String jsonResponse = ...;
Tours tours = (new Gson()).fromJson(jsonResponse, Tours.class);

, . , OkHttp HTTP- HttpClient, , , .

+2

Source: https://habr.com/ru/post/1584224/

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