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How to transfer data from a servlet to an Android application

I have a form in android upon submit im inserting it into database using servlet i have to show to user that form was inserted successfully. this is my application import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.sql.Connection; import java.sql.DriverManager; import java.sql.Statement; import java.util.ArrayList; /** * * @author trainee */ public class form extends HttpServlet { String name; String password; Connection con = null; Statement stmt = null; /** * Processes requests for both HTTP <code>GET</code> and <code>POST</code> methods. * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ /* TODO output your page here out.println("<html>"); out.println("<head>"); out.println("<title>Servlet form</title>"); out.println("</head>"); out.println("<body>"); out.println("<h1>Servlet form at " + request.getContextPath () + "</h1>"); out.println("</body>"); out.println("</html>"); */ @Override protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { try { } catch(Exception ex) { } } /** * Handles the HTTP <code>POST</code> method. * @param request servlet request * @param response servlet response * @throws ServletException if a servlet-specific error occurs * @throws IOException if an I/O error occurs */ @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { try { Class.forName("com.mysql.jdbc.Driver"); con =DriverManager.getConnection ("jdbc:mysql://localhost:3306/Login","root", ""); String nn=request.getParameter("name"); String pass=request.getParameter("pass"); String email=request.getParameter("email"); stmt=con.createStatement(); String query="insert into users values('"+nn+"','"+pass+"','"+email+"');"; int v=stmt.executeUpdate(query); ArrayList<String> arr=new ArrayList<String>(); arr.add("inserted"); System.out.println("sent response back..."); } catch(Exception ex) { } } /** * Returns a short description of the servlet. * @return a String containing servlet description */ @Override public String getServletInfo() { return "Short description"; }// </editor-fold> }

this is my android app.

 package org.me.loginandroid; import java.io.BufferedReader; import java.io.InputStream; import java.io.InputStreamReader; import java.util.ArrayList; import java.io.*; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.NameValuePair; import org.apache.http.client.HttpClient; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.message.BasicNameValuePair; import org.json.JSONArray; import org.json.JSONObject; import android.app.Activity; import android.content.Intent; import android.os.Bundle; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.EditText; import android.widget.TextView; import org.apache.http.client.methods.HttpGet; public class MainActivity extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); Button btn1 = (Button) findViewById(R.id.submit); btn1.setOnClickListener(listener_login); } private OnClickListener listener_login = new OnClickListener() { boolean check = false; public void onClick(View v) { EditText emailText = (EditText) findViewById(R.id.email); EditText passText = (EditText) findViewById(R.id.password); EditText nameText = (EditText) findViewById(R.id.uname); String name = nameText.getText().toString(); String email = (emailText.getText().toString()); String pass = (passText.getText().toString()); String result = ""; ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(); nameValuePairs.add(new BasicNameValuePair("name", name)); nameValuePairs.add(new BasicNameValuePair("pass", pass)); nameValuePairs.add(new BasicNameValuePair("email", email)); try { HttpClient httpclient = new DefaultHttpClient(); HttpPost httppost = new HttpPost("http://10.0.2.2:8084/Login/form"); httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs)); HttpResponse response = httpclient.execute(httppost); HttpEntity entity = response.getEntity(); InputStream is = entity.getContent(); 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(); result = sb.toString(); TextView lbl = (TextView) findViewById(R.id.lbl); lbl.setText(result); } catch (Exception e) { TextView tv = (TextView) findViewById(R.id.err); tv.setText("Error parsing data " + e.toString()); System.out.println("Error parsing data " + e.toString()); } //parse json data try { boolean check=false; ArrayList<String> arrays=new ArrayList<String>(); for(int i=0;i<arrays.size();i++) { if(arrays.get(i).equals("Inserted")) { check=true; } else { } } if(check) { Intent myintent = new Intent(MainActivity.this, welcome.class); startActivity(myintent); } else { TextView tv = (TextView) findViewById(R.id.err); tv.setText("Data was not inserted properly"); } } catch (Exception e) { //setContentView(R.layout.notify); TextView tv = (TextView) findViewById(R.id.err); tv.setText(e.toString()); System.out.println("log_tag" + "Error parsing data "); } } }; }
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4 answers

Here you can check. There is a full description with sample code.

Send arraylist from servlet to android app

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You need to do a URLConnection on the servlet page and do this. Example for him: How to download a file / image from a URL to your device

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first of all, if your doGet() and doPost() do the same, you can call one from the other by sending request and response

Secondly, you can pass ArrayList<E> to your Android app. Both Servlet and Android APIs have it

edit: You need to read from the InputStream generated by the HttpURLConnection object. http://developer.android.com/reference/java/io/InputStream.html

check out this book: used book http://www.amazon.com/Professional-Android-Application-Development-Programmer/dp/0470565527 )

String input = getString(R.string.input);
try {
URL url = new URL(input);
URLConnection connection = url.openConnection();
HttpURLConnection http = (HttpURLConnection)connection;
int response = http.getResponseCode();
if (response == HttpURLConnection.HTTP_OK) {
InputStream is = http.getInputStream();
//do whatever you want with the stream
}
}
catch (MalformedURLException exception) { }
catch (IOException exception) { }

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you can get data from servlet into andriod application via json format . Please go through this http://wiebe-elsinga.com/blog/?p=405 to get an idea of ​​how to invoke the servlet from the andriod application and get the response back in json format.

calling servlet from Andriod

  private InputStream callService(String text) { InputStream in = null; SERVLET_URL = http://wizkid.com/web/updateServlet"; try { URL url = new URL(SERVLET_URL); URLConnection conn = url.openConnection(); HttpURLConnection httpConn = (HttpURLConnection) conn; httpConn.setRequestMethod("POST"); httpConn.setDoInput(true); httpConn.setDoOutput(true); httpConn.connect(); DataOutputStream dataStream = new DataOutputStream(conn .getOutputStream()); dataStream.writeBytes(text); dataStream.flush(); dataStream.close(); int responseCode = httpConn.getResponseCode(); if (responseCode == HttpURLConnection.HTTP_OK) { in = httpConn.getInputStream(); } } catch (Exception ex) { display("Error: Not not connect"); } return in; }

// Get data from the server in andriod

  private String getResultFromServlet(String text) { String result = ""; InputStream in = callService(text); if (in != null) { JSONObject jsonResponse; try { jsonResponse = new JSONObject(convertStreamToString(in)); result = jsonResponse.getString("output"); } catch (JSONException e) { result = "Error: JSON Object couldn't be made"; } } else { result = "Error: Service not returning result"; } return result; }
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Source: https://habr.com/ru/post/1336104/

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