I'm trying to make a client in Android. This clients runs a thread that creates the client socket and launches another thread that is always listening to the socket to receive Strings. Everything is OK when I send a String from the client to a Java server running in a PC, but when I send a String from the server to the Android client the app finishes. Why do I get this error?
Here is the code of the main Activity of the client:
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
TextView chatHistorial;
EditText msg;
Socket client;
DataInputStream in;
DataOutputStream out;
Boolean cerrar;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Thread t = new Thread(new Runnable(){
#Override
public void run() {
try{
client = new Socket("192.168.1.33", 4444);
in = new DataInputStream(client.getInputStream());
out = new DataOutputStream(client.getOutputStream());
cerrar = false;
chatHistorial = (TextView) findViewById(R.id.chatHistorial);
msg = (EditText) findViewById(R.id.msg);
ThreadLectura tl = new ThreadLectura(in, cerrar, chatHistorial);
tl.start();
}
catch(Exception e){
// ...
}
}
});
t.start();
findViewById(R.id.enviar).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
String cadena = msg.getText().toString();
try {
out.writeUTF(cadena);
} catch (IOException e) {
// ...
}
if(cadena.equals("exit"))
cerrar = true;
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
//getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
class ThreadLectura extends Thread{
DataInputStream in;
String cadena;
TextView chatHistorial;
Boolean cerrar;
public ThreadLectura(DataInputStream in, Boolean cerrar, TextView tv){
this.in = in;
this.cerrar = cerrar;
chatHistorial = tv;
}
#Override
public void run(){
try{
while(!cerrar){
cadena = in.readUTF();
chatHistorial.append("Has recibido: " + cadena);
}
}
catch(IOException ioe){
System.out.println("Error de entrada/salida: "+ioe.getMessage());
}
}
}
It's hard to say without seeing your logcat output, but I'm betting it's because you are attempting to modify the UI from within your background thread. This line within ThreadLectura:
chatHistorial.append("Has recibido: " + cadena);
is probably the issue, as chatHistorial is a TextView. You need to only modify the UI from within the main UI thread.
Related
I am trying to send data from an an Android app to a Servlet.
My Android Application is working properly.
The issue is only with the request sent to the Servlet. It gives error BasicNetwork.performRequest: Unexpected response code 500
Note: I am using Android Volley library to send my request to the Servlet.
Below I have mentioned:
1. My Android app code
2. My Servlet Code
3. LogCat
My Android App: MainActivity.java File
package com.example.hawk;
import java.util.HashMap;
import java.util.Map;
import com.android.volley.AuthFailureError;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import android.support.v7.app.ActionBarActivity;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
public class MainActivity extends Activity implements View.OnClickListener {
EditText var_sp = null;
EditText var_ect = null;
EditText var_er = null;
EditText var_iat = null;
EditText var_atp = null;
Button submit;
RequestQueue rq = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
v1 = (EditText) findViewById(R.id.sp);
v2 = (EditText) findViewById(R.id.ect);
v3 = (EditText) findViewById(R.id.er);
v4 = (EditText) findViewById(R.id.iat);
v5 = (EditText) findViewById(R.id.atp);
submit = (Button) findViewById(R.id.submit);
rq=Volley.newRequestQueue(this);
submit.setOnClickListener(this);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
#Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.submit:
new Thread(new Runnable() {
public void run() {
try{
StringRequest postReq = new StringRequest(Request.Method.POST, "http://192.168.0.103:8080/ServletABC",new Response.Listener<String>() {
protected Map<String, String> getParams() throws AuthFailureError {
Map<String, String> params = new HashMap<String, String>();
params.put("var1",v1.getText().toString());
params.put("var2",v2.getText().toString());
params.put("var3",v3.getText().toString());
params.put("var4",v4.getText().toString());
params.put("var5",v5.getText().toString());
return params;
}
#Override
public void onResponse(String response) {
// TODO Auto-generated method stub
}
}, null);
rq.add(postReq);
}catch(Exception e)
{
e.printStackTrace();
}
}
}).start();
break;
}
}
}
My Servlet:
import java.io.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.sql.*;
public class OBD_Feeder extends HttpServlet{
// JDBC driver name and database URL
public static final String JDBC_DRIVER="com.mysql.jdbc.Driver";
public static final String DB_URL="jdbc:mysql://localhost/Test";
// Database credentials
public static final String USER ="xxxx";
public static final String PASS ="xxxx";
Connection conn;
Statement stmt;
public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException,IOException
{
response.setContentType("text/html");
PrintWriter out = response.getWriter();
double v1=Double.parseDouble(request.getParameter("var1"));
double v2=Double.parseDouble(request.getParameter("var2"));
double v3=Double.parseDouble(request.getParameter("var3"));
double v4=Double.parseDouble(request.getParameter("var4"));
double v5=Double.parseDouble(request.getParameter("var5"));
Calendar calendar = Calendar.getInstance();
java.sql.Timestamp today_ts = new java.sql.Timestamp(calendar.getTime().getTime());
//System.out.println("TimeStamp: "+today_ts);
try{
// Register JDBC driver
Class.forName("com.mysql.jdbc.Driver");
// Open a connection
conn =DriverManager.getConnection(DB_URL,USER,PASS);
// Execute SQL query
stmt = conn.createStatement();
PreparedStatement pst =(PreparedStatement) conn.prepareStatement("insert into obd_test1(speed,coolant_temp,engine_rpm,in_air_temp,throttle_position, time_stamp) values(?,?,?,?,?,?)");
pst.setDouble(1,v1);
pst.setDouble(2,v2);
pst.setDouble(3,v3);
pst.setDouble(4,v4);
pst.setDouble(5,v5);
pst.setTimestamp(6,today_ts);
System.out.println("DB Query: "+pst.toString());
//Query execution
int i = pst.executeUpdate();
//conn.commit();
String msg=" ";
if(i!=0){msg="Record has been inserted";}
else{msg="failed to insert the data";}
System.out.println("DB Transaction Status: "+msg);
String docType ="<!doctype html public \"-//w3c//dtd html 4.0 "+"transitional//en\">\n";
out.println(docType +
"<html>\n"+
"<head><title>OBD Feeder</title></head>\n"+
"<body bgcolor=\"#f0f0f0\">\n"+
"<h1 align=\"center\">DATA Received:</h1>\n"+
"<ul>\n"+msg+"</ul>\n"+
"</body></html>");
pst.close();
stmt.close();
conn.close();
}catch(SQLException se){ se.printStackTrace();}//Handle errors for JDBC se.printStackTrace();
catch(Exception e){ e.printStackTrace();}//Handle errors for Class.forName e.printStackTrace();
finally
{ //finally block used to close resources
try{
if(stmt!=null)
stmt.close();
}catch(SQLException se2){ se2.printStackTrace();}// nothing we can do
try{
if(conn!=null)
conn.close();
}catch(SQLException se){ se.printStackTrace();
}//end finally try
}
}
}
My LogCat:
08-15 10:42:55.128: I/HAWK(29403): POST Request: [ ] http://192.168.0.102:8080/OBD_Feeder 0x85adf656 NORMAL 3
08-15 10:42:55.408: E/Volley(29403): [1056] BasicNetwork.performRequest: Unexpected response code 500 for http://192.168.0.102:8080/ServletABC
08-15 10:42:55.408: D/HAWK(29403): Error: null
08-15 10:44:56.648: W/IInputConnectionWrapper(29403): getTextBeforeCursor on inactive InputConnection
Check if you are using correct SDK
For Android Studio / IntelliJIDEA:
File -> Project Structure -> Project -> Project SDK
Modules -> Check each modules "Module SDK"
Preferably, you should use "Google API (x.x)" instead of Android API
Use the IP 10.0.2.2.
"192.168.0.103:8080/ServletABC" to
"10.0.2.2:8080/ServletABC"
After an exhaustive search on the internet, I managed to assemble a code that sends data to a server socket created in VB.NET.
' Here is my VB.NET code
Imports System.Net.Sockets
Imports System.Text
Imports System.Net
Public Module MainModule
Private TcpListener As New TcpListener(IPAddress.Parse("10.0.0.100"), 11000)
Dim TcpClient As New TcpClient
Dim NetworkStream As NetworkStream
Public Sub Main()
TcpListener.Start()
While (True)
TcpClient = TcpListener.AcceptTcpClient()
NetworkStream = TcpClient.GetStream()
Dim r_byt(TcpClient.ReceiveBufferSize) As Byte
Dim r_byt_size As Integer = NetworkStream.Read(r_byt, 0, TcpClient.ReceiveBufferSize) - 1
Dim data As String = Encoding.ASCII.GetString(r_byt, 0, r_byt_size)
Console.WriteLine(data)
Dim s_byt() As Byte = Encoding.ASCII.GetBytes("testing")
NetworkStream.Write(s_byt, 0, s_byt.Length)
NetworkStream.Flush()
NetworkStream.Close()
TcpClient.Close()
End While
TcpListener.Stop()
End Sub
End Module
// Here is my Android code
package com.javacodegeeks.android.androidsocketclient;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.Socket;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class Client extends Activity {
private static final String SERVER_IP = "10.0.0.100";
private static final int SERVER_PORT = 11000;
private Socket socket;
private EditText InputText = null;
private Button ButtonSend = null;
private TextView LabelReceived = null;
private Thread thread = null;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
InputText = (EditText)findViewById(R.id.InputText);
ButtonSend = (Button)findViewById(R.id.ButtonSend);
LabelReceived = (TextView)findViewById(R.id.LabelReceived);
thread = new Thread(new ClientThread());
if (thread != null) {
thread.start();
}
ButtonSend.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
try {
if (socket != null) {
PrintWriter out = new PrintWriter(socket.getOutputStream());
out.println(InputText.getText().toString());
out.flush();
out.close();
} else {
LabelReceived.setText("socket is null!");
}
} catch (Exception e) {
LabelReceived.setText(e.getMessage());
}
}
});
}
class ClientThread implements Runnable {
public void run() {
try {
InetAddress IAddress = InetAddress.getByName(SERVER_IP);
socket = new Socket(IAddress, SERVER_PORT);
} catch (Exception e) {
socket = null;
}
}
}
}
The two are working, when I press the "send button" it goes to the server, but when I try to do it again nothing is received.
I am quite new to android developing
I have written the following code to connect my android to a ftp server
package com.example.test1;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import org.apache.commons.net.ftp.*;
public class MainActivity extends Activity {
public FTPClient mFTPClient = null;
Button but;
public boolean ftpConnect(String host, String username, String password, int port) {
try {
mFTPClient = new FTPClient();
// connecting to the host
mFTPClient.connect(host, port);
// Now check the reply code, if positive mean connection success
if (FTPReply.isPositiveCompletion(mFTPClient.getReplyCode())) {
// Login using username & password
boolean status = mFTPClient.login(username, password);
mFTPClient.setFileType(FTP.BINARY_FILE_TYPE);
mFTPClient.enterLocalPassiveMode();
return status;
}
} catch(Exception e) {
CharSequence c = ""+e;
int d = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(getApplicationContext(),c,d);
toast.show();
}
return false;
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
but=(Button)findViewById(R.id.button1);
but.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
ftpConnect("127.0.0.1","userName","Password",21);
}
});
}
}
But this gives a networkOnMainThread Exception so after searching i found out i have to use AsyncTask but i have no idea how to implement it!
public void onClick(View v) {
new AsyncTask() {
publc Object doInBackground(Object...) {
try {
mFTPClient = new FTPClient();
// connecting to the host
mFTPClient.connect(host, port);
// Now check the reply code, if positive mean connection success
if (FTPReply.isPositiveCompletion(mFTPClient.getReplyCode())) {
// Login using username & password
boolean status = mFTPClient.login(username, password);
mFTPClient.setFileType(FTP.BINARY_FILE_TYPE);
mFTPClient.enterLocalPassiveMode();
return status;
}
} catch(Exception e) {
return e;
}
}
}
public void onPostExecute(Object res) {
if (res instanceof Exception) {
int d = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(getApplicationContext(),""+res,d);
toast.show();
}
}
}.execute();
Another temporary 'workaround' is to set your android:targetSdkVersion="9" or below in AndroidManifest.xml, as this exception was introduced in API level 10.
Documentation on Android Developers is pretty rich on such an important topic. You'll get it through with that.
http://developer.android.com/reference/android/os/AsyncTask.html
You may want to refer the NetworkConnect sample from the Android SDK.
I would like to add a webserver to my android application for uploading small files to the phone.
The user would start the webserver from the phone by hitting a button. He would then see an ip address that can be accessed by any browser from a pc. The website behind this ip address should show a file upload opportunity.
My question is: Is there an open source project similar to my needs? Or how would you recommend doing this?
you can use NanoHttpd link it's very weight android web server that is nicely embbedible..
package .....;
import java.io.IOException;
import java.util.Map.Entry;
import java.util.Properties;
import android.app.Activity;
import android.net.wifi.WifiManager;
import android.os.Bundle;
import android.os.Handler;
import android.widget.TextView;
public class AndroidWebServerActivity extends Activity {
private static final int PORT = 8765;
private TextView hello;
private MyHTTPD server;
private Handler handler = new Handler();
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
}
#Override
protected void onResume() {
super.onResume();
try {
server = new MyHTTPD();
} catch (IOException e) {
e.printStackTrace();
}
}
#Override
protected void onPause() {
super.onPause();
if (server != null)
server.stop();
}
private class MyHTTPD extends NanoHTTPD {
public MyHTTPD() throws IOException {
super(PORT, null);
}
#Override
public Response serve(String uri, String method, Properties header, Properties parms, Properties files) {
final StringBuilder buf = new StringBuilder();
for (Entry<Object, Object> kv : header.entrySet())
buf.append(kv.getKey() + " : " + kv.getValue() + "\n");
handler.post(new Runnable() {
#Override
public void run() {
}
});
final String html = "<html><head><head><body><h1>Hello, World</h1></body></html>";
return new NanoHTTPD.Response(HTTP_OK, MIME_HTML, html);
}
}
}
I am trying to establish a chatting application between a server and a client, but the application could not run because of this line of code : message = (String) input.readObject();
because at first, inputStream is null ! any one can help please ? here is my code
package com.example.test;
import java.io.BufferedReader;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.OptionalDataException;
import java.net.Socket;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.Bundle;
import android.os.StrictMode;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class MainActivity extends Activity {
private Button send;
private Button connect;
private EditText userText;
private TextView chatWindow;
private String serverIP;
private ObjectOutputStream output;
private ObjectInputStream input;
private String message = "";
private Socket connection;
#SuppressLint({ "NewApi", "NewApi", "NewApi" })
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
}
serverIP = "192.168.1.4";
//userText.setEnabled(false);
send = (Button)findViewById(R.id.button1);
connect = (Button)findViewById(R.id.button2);
chatWindow =(TextView)findViewById(R.id.textView1);
userText = (EditText)findViewById(R.id.editText1);
userText.setHint("Enter your message here");
connect.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
//connect to the server
try{
connectToServer();
setupStreams();
}catch(EOFException eofException){
showMessage("\n client terminated the connection");
}catch(IOException ioException){
ioException.printStackTrace();
}
}
});
send.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
String message = userText.getText().toString();
sendMessage(message);
userText.setText("");
}
});
while(true){
try{
message = (String) input.readObject();
showMessage("\n" + message + " NULL ");
chatWindow.refreshDrawableState();
}catch(ClassNotFoundException classNotFoundException){
showMessage("\n I don't know that object type");
}
catch(NullPointerException e){
e.printStackTrace();
}
catch (OptionalDataException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
} // end of onCreate
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
//connect to the server
private void connectToServer() throws IOException {
showMessage("Attempting connection... \n");
connection = new Socket( "192.168.1.4", 6789);
showMessage("Connected to " + connection.getInetAddress().getHostName() );
}
//setup streams to send and receive messages
private void setupStreams() throws IOException{
output = new ObjectOutputStream(connection.getOutputStream());
output.flush();
input = new ObjectInputStream(connection.getInputStream());
showMessage("\n Your streams are now good to go! \n ");
}
//whileChatting with server
private void whileChatting() throws IOException{
try{
message = (String) input.readObject();
showMessage("\n" + message + " NULL ");
chatWindow.refreshDrawableState();
}catch(ClassNotFoundException classNotFoundException){
showMessage("\n I don't know that object type");
}
}
//close the streams and sockets
private void closeCrap(){
showMessage("\n closing crap down");
ableToType(false);
try{
output.close();
input.close();
connection.close();
}catch(IOException ioException){
ioException.printStackTrace();
}
}
// gives user permission to type into the text box
private void ableToType(final boolean tof){
userText.setEnabled(tof);
}
// send messages to server
private void sendMessage(String message){
try{
output.writeObject("CLIENT - " + message);
output.flush();
showMessage("\nCLIENT - " + message);
}catch(IOException ioException){
chatWindow.append("\n somethine messed up sending message!");
}
}
//change/update chatWindow
private void showMessage(final String m){
chatWindow.append(m);
chatWindow.refreshDrawableState();
}
} // end of class MainActivity
Your code is definitely not following any good UI guidelines: You are doing network operations on the Main (UI) Thread, and you have an infinite loop in onCreate(). Android should actually offer to force close your app if nothing crashes. Now, a likely cause for the null problem you are facing:
setupStreams() is only called upon a button click. However, your while (true) loop is in the root of onCreate(). This means that as soon as the click listeners are made and set, the loop runs, attempts to read in from input and fails since setupStreams() hasn't been called.
So please don't do away with StrictMode - it's there to help, and thing about your code from an event driven standpoint ("Once X happens, then do Y"). And also get rid of loops in the Main (UI) Thread. Loops are fine for Console windows, but with UIs (which have their own complex lifecycle), you can't do this without freezing a lot of things.
Do all of your network tasks in doInBackground() ofAsyncTask then update your UI variables in onPostExecute(). Something like
public class TalkToServer extends AsyncTask<String, String, String> {
#Override
protected void onPreExecute() {
super.onPreExecute();
}
#Override
protected void onProgressUpdate(String... values) {
super.onProgressUpdate(values);
}
#Override
protected String doInBackground(String... params) {
//do your work here
return something;
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
// do something with data here-display it or send to mainactivity
}
Here is the documentation on AsyncTask
Another thing to consider is you are using the variable message in different places which may cause you problems. It looks like you have it defined as a member variable then as a local variable to other methods. You don't want to re-use the same variable name this way. Don't define String message multiple times in the same Activity