Hey I am trying to upload an image to my ftp server but from some reason the connection isn't working and I can figure out why..
here is the connection code:
public void uploadingFilestoFtp() throws IOException {
FTPClient ftpclient = new FTPClient();
FileInputStream fis = null;
boolean result;
try {
ftpclient.connect(host);
result = ftpclient.login(username, password);
if (result == true) {
System.out.println("Logged in Successfully !");
} else {
System.out.println("Login Fail!");
return;
}
ftpclient.setFileType(FTP.BINARY_FILE_TYPE);
ftpclient.changeWorkingDirectory("/");
File file = new File(imagePath);
fis = new FileInputStream(file);
// Upload file to the ftp serverresult = ftpclient.storeFile(testName, fis);
if (result == true) {
System.out.println("File is uploaded successfully");
} else {
System.out.println("File uploading failed");
}
ftpclient.logout();
} catch (FTPConnectionClosedException e) {
e.printStackTrace();
} finally {
try {
ftpclient.disconnect();
} catch (FTPConnectionClosedException e) {
System.out.println(e);
}
}
}
I am using exactly the details of the ftp server but it doesn't seems to work
How can I get this mehod to work?
android.os.NetworkOnMainThreadException
You are trying to make a network request from the UI thread. Android doesn't allow any network request from main(UI) thread. You need to create a class extending AsyncTask.
public class UploadFileTask extends AsyncTask <Void, Void, Void > {
public void onPreExecute() {
}
public void doInBackground(Void...unused) {
uploadingFilestoFtp(); //Call your method here. Put necessary try-catch block.
}
public void onPostExecute(Void unused) {
// do something when upload is done.
}
}
Note that this onPreExecute() and onPostExecute() run on the UI thread. So you can do any stuff before or after the network call. Make the network call in doInBackground() method.
Check this answer How to fix android.os.NetworkOnMainThreadException?
Related
I'm currently writing a client-server application where data should be transferred to the server to process the data. For building the connection I use ServerSocket and Socket and for sending the data I use OutputStream + ObjectOutputStream on the client-side and InputStream + ObjectInputStream on the server-side. The connection is currently running on localhost.
The object I try to transfer is a serializable class that only contains String parameters.
The problem I'm facing now is that readObject() immediately throws an EOFException as soon as the OutputStreams of the client are initialized (which leads to an initialization of the InputStreams of the server at the same time) instead of waiting for input from the client.
I send the data from the client using this code:
public void send(DataSet dataSet) {
if (!clientStreamsEstablished) {
initiateClientStreams();
}
try {
out.writeObject(dataSet);
} catch (IOException e) {
e.printStackTrace();
}
}
This method is only called when I hit the "submit"-button in the UI so it will not be executed on start of the application.
The data is currently (already tried a ton of other approaches with and without while() loop etc., etc.) read on the server using this method:
private void waitForInput(ObjectInputStream in, InputStream listeningPort) {
boolean dataReceived = false;
DataSet dataSet = null;
System.out.println("waiting ...");
while (!dataReceived) {
try {
Object temp = in.readObject(); // <-- EOFException is thrown here
boolean test = false;
if (temp instanceof DataSet) {
dataSet = (DataSet) temp;
}
} catch (ClassNotFoundException | IOException e) {
e.printStackTrace();
break;
}
}
System.out.println("Test 2: " + dataSet.toString());
if (dataReceived) {
waitForInput(in, listeningPort);
}
}
As soon as the client thread on the server reaches this line (see code-comment above) I get this stacktrace:
java.io.EOFException
at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2626)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1321)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:373)
at com.labdashboardserver.ClientThread.waitForInput(ClientThread.java:53)
at com.labdashboardserver.ClientThread.run(ClientThread.java:43)
Exception in thread "Thread-2" java.lang.NullPointerException
at com.labdashboardserver.ClientThread.waitForInput(ClientThread.java:65)
at com.labdashboardserver.ClientThread.run(ClientThread.java:43)
The reason for the second part of the stacktrace containing the NullPointerException is apparent as due to the EOFExcpetion the dataSet never is initialized.
However from my point of view readObject() should block and wait for the client to send ANY data before starting to read it and throw an EOF. I feel like I read through half of Stack Overflow and other forums searching for an answer but the articles I found only discuss reading files or only immediate temporary streams which are closed afterwards.
Edit
I initialize the connection before calling the UI in my main method:
public static void main(String[] args) {
connector = new LabConnector();
connector.run();
if (connector.getConnectionEstablished()) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
frame = new LabUI();
frame.setVisible(true);
} catch (Exception e) {
JOptionPane.showMessageDialog(null,
"Error Message:\n" + e.getMessage() + "\nProgram shutting down!", "Critical Error", 0);
}
}
});
}
While in the LabConnector class I initialize the streams and connection like this:
public void run() {
try {
establishConnection();
} catch (UnknownHostException e) {
retryConnection(e);
} catch (IOException e) {
retryConnection(e);
}
if (connectionEstablished) {
initiateClientStreams();
}
}
private void establishConnection() throws UnknownHostException, IOException {
client = new Socket(HOST_IP_ADRESS, HOST_PORT);
JOptionPane.showMessageDialog(null, "Connected to Server!");
connectionEstablished = true;
}
private void initiateClientStreams() {
try {
sendingPort = client.getOutputStream();
out = new ObjectOutputStream(sendingPort);
clientStreamsEstablished = true;
} catch (IOException e) {
e.printStackTrace();
}
}
I am currently on the beginner level when it comes to Android & I am currently scratching my head over an issue that I am currently facing.
I am creating an Android app to check if "cache.json" exists in the internal storage:
If it does not exist then first create it & write a string fetched from HTTP API to the file (replaced with fixed string in code below).
Regardless, read the file after writing is done (if necessary) & do appropriate stuff.
This is the code snippet:
public class ShowClasses extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
filename = "cache.json";
file = new File(getApplicationContext().getFilesDir(), filename);
if (file.exists()) {
System.out.println("EXISTS");
} else {
System.out.println("DOES NOT EXIST");
writeFile();
}
readFile();
}
public void writeFile() {
new JsonTask().execute(email);
}
public void readFile() {
FileInputStream fin = null;
try {
fin = new FileInputStream(file);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
int c;
result = "";
try {
while( (c = fin.read()) != -1){
result = result + Character.toString((char)c);
}
} catch (IOException e) {
e.printStackTrace();
}
try {
fin.close();
} catch (IOException e) {
e.printStackTrace();
}
return;
}
private class JsonTask extends AsyncTask<String, Void, String> {
protected void onPreExecute() {
result = ""; // Clear result
super.onPreExecute();
pd.setMessage("Please wait");
pd.setCancelable(false);
pd.show();
}
protected String doInBackground(String... params) {
return "THIS STRING IS GOING TO BE RETURNED " + params[0];
}
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
FileOutputStream fileout = null;
try {
fileout = new FileOutputStream(file);
fileout.write(result.getBytes());
//display file saved message
msg("File saved successfully!");
} catch (Exception e) {
e.printStackTrace();
}
try {
fileout.close();
} catch (IOException e) {
e.printStackTrace();
}
if (pd.isShowing()){
pd.dismiss();
}
}
}
}
I have tried to remove un-necessary part of the code so that it is smaller in length.
The actual issue I am facing is when writeFile() & readFile() both are called. I get a FileNotFoundException in readFile() when I open the stream even though the file should be created since writeFile() is called before readFile().
If I writeFile on one execution & then call readFile() on the other, it simply works as it should be.
This is the error that I am facing.
System.err: java.io.FileNotFoundException: /data/user/0/host.timetable.timetablenotifier/files/cache.json (No such file or directory)
System.err: at java.io.FileInputStream.open(Native Method)
Any help would be really appreciated.
Thanks
writeFile() is asynchronous. When that method returns, nothing has happened with respect to this file. At most, onPreExecute() of your JsonTask might be called. So, when you call readFile(), the file will not exist yet.
Beyond that:
You have an AsyncTask that you use in writeFile(), but you do your disk I/O in onPostExecute(), and that method is called on the main application thread.
You are doing disk I/O on the main application thread in readFile().
You catch exceptions, log them, but then continue executing your code, when most of those exceptions mean that the later statements are going to fail as well.
Reading in data one int at a time has not been a recommended approach for getting close to 20 years, for performance reasons.
You will have multiple issues related to configuration changes, such as screen rotations, as neither your AsyncTask nor your ProgressDialog account for configuration changes
Also:
getApplicationContext().getFilesDir() could be replaced by getFilesDir() in onCreate()
You do not need createNewFile()
AsyncTask runs in a background thread so the other code in the main thread doesn't wait for the execution to complete. In simpler terms, your readFile() method is executed before writeFile() completes and hence there is a FileNotFoundException. What would work for you is if you put the readFile() method at the end of the onPostExecute() method inside your Asynctask
Provided I have an array of image URLs, I am trying to download all these images one-by-one using glide. Presently, I am able to download a single image when I provide its URL. And here is the code:
private void downx()
{
File sd = getExternalCacheDir();
File folder = new File(sd, "/mobio/");
if (!folder.exists()) {
if (!folder.mkdir()) {
Log.e("ERROR", "Cannot create a directory!");
} else {
folder.mkdirs();
}
}
final File[] fileName = {new File(folder, "one.jpg"), new File(folder, "two.jpg"),new File(folder, "three.jpg")};
new AsyncTask<Void, Void, Void>() {
#Override
protected Void doInBackground(Void... params)
{
try
{
theBitmap = Glide.
with(getApplicationContext()).
load(urls[2]).
asBitmap().
into(Target.SIZE_ORIGINAL,Target.SIZE_ORIGINAL).
get();
}
catch (final ExecutionException e)
{
Log.e("TAG", e.getMessage());
}
catch (final InterruptedException e)
{
Log.e("TAG", e.getMessage());
}
return null;
}
#Override
protected void onPostExecute(Void dummy) {
if (null != theBitmap) {
// The full bitmap should be available here
Log.d("TAG", "Image loaded");
Log.e("GLIDE","I am Ready");
try {
FileOutputStream outputStream = new FileOutputStream(String.valueOf(fileName[1]));
theBitmap.compress(Bitmap.CompressFormat.JPEG, 100, outputStream);
outputStream.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}.execute();
}
Now the problem is: What approach do I adopt if I need to download multiple images, and how do I force my code to adapt to handle multiple downloads?
I have used a class which takes a list of URLs and downloads the Images to a file. Please check this Gist for more. This uses Picasso to download Images but you can edit the download code to use glide as well. Should be a one line change. Hope this helps.
https://gist.github.com/bpr10/a765a015bf1c774816ba58c7ae6413d6
I guess it will be better to use Download Manager as it will handle queuing, network availability etc.
I am logging into the ftp account using AsyncTask but I keep getting this error,
12-31 15:26:19.637: E/dalvikvm(5986): Could not find class 'org.apache.commons.net.ftp.FTPClient', referenced from method com.example.testme.Processing.connnectingwithFTP
I can understand that my method inside Asynctask is not able to find the FTPClient class eventhough it is imported fine. But I don't how to make my inner AsyncTask method find the FTPClient class.
Here is my code,
AsyncTask class
class Processing extends AsyncTask<Object, Void, Void> {
#Override
protected Void doInBackground(Object... params) {
connnectingwithFTP("host", "username",
"password");
return null;
}
public void connnectingwithFTP(String ip, String userName, String pass) {
boolean status = false;
try {
FTPClient mFtpClient = new FTPClient();
mFtpClient.setConnectTimeout(10 * 1000);
mFtpClient.connect(InetAddress.getByName(ip));
status = mFtpClient.login(userName, pass);
Log.e("isFTPConnected", String.valueOf(status));
if (FTPReply.isPositiveCompletion(mFtpClient.getReplyCode())) {
mFtpClient.setFileType(FTP.ASCII_FILE_TYPE);
mFtpClient.enterLocalPassiveMode();
FTPFile[] mFileArray = mFtpClient.listFiles();
Log.e("Size", String.valueOf(mFileArray.length));
}
} catch (SocketException e) {
e.printStackTrace();
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
and this is what I am doing in onCreate method,
Processing p1 = new Processing();
p1.execute();
You should add the jar file to the libs folder of your project. Also, make sure it's checked under the Order and Export tab.
I recently started learning android development (am new to java as well) and I am currently working on a chat/messenger application
The problem I am facing, as the title says, is that the listview in which the messages are shown does not update on the device, unless scrolled, but it works fine on the virtual machine. I only tested on LG Optimus l5 II so far, but i need to fix this anyway.
I think it has something to do with multithreading, because this didn't happen until i added some new threads, so the adapter for listview, android manifest and rest I say are set up correctly. I can add them if it helps.
The 2 threads i added that might cause this:
Checks the connection status and if disconnected tries to reconnect.
The thread used for communicating with the server.
I tested running only with the second thread on, and the problem still occurs.
I want to specify this is the first time I try something like this (servers-client, multithreading, java, android (I'm still in college and they don`t teach us these kinds of stuff there) ), and had no documentation ahead regarding how I should set up the communication between the server and the client. This is the most efficient way I could think of.
this is at the end of onCreate:
StartConnectingRoutine(); // so you know where it all starts
and the code for it:
private void StartConnectingRoutine()
{
Thread t = new Thread()
{
#Override
public void run()
{
while(true)
{
if(!connected)
{
if( connect != null)
{
if(!connect.isAlive())
{
ConnectListener();
}
}
else
{
ConnectListener();
}
}
try {
sleep(CONNECTION_CHECK_TIME_MS); // this is set to 10000 (10 seconds)
} catch (InterruptedException e) {
Log.e("Intrerrupted", e.toString());
}
}
}
};
t.start();
}
and the connectListener():
private void ConnectListener()
{
Log.d("Connecting", "Connecting...");
connect = new Thread()
{
JSONObject info = new JSONObject();
String receivedMessage;
#Override
public void run()
{
try {
info.put("Name", user.GetName());
info.put("PORT", MY_PORT);
info.put("IPv4", getIpAddress());
} catch (JSONException e1) {
Log.e("JSON", "JSON error: " + e1.toString());
}
try
{
ServerSocket = new Socket(SERVER_IP, SERVER_PORT);
dis = new DataInputStream(ServerSocket.getInputStream());
dos = new DataOutputStream(ServerSocket.getOutputStream());
dos.writeUTF(info.toString());
dos.flush();
String response = dis.readUTF();
if(response.equals("connected"))
{
Log.d("Connect", "Connected!");
connected = true;
}
else
Log.d("Connect", "Failed to connect!");
while(connected)
{
receivedMessage = dis.readUTF();
DisplayNewMessage(new MMessage(receivedMessage, MMessage.MessageType.Received));
}
}catch(SocketException e)
{
try {
if(connected)
{
ServerSocket.close();
dis.close();
dos.close();
connected = false;
}
} catch (IOException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}
catch(Exception e)
{
Log.d("Connect", "Failed to connect");
Log.e("Connect", e.toString());
connected = false;
}
}
};
connect.start();
}
Fixed:
Reconnecting thread (i tried using asyncTask for this too, but it wouldn`t open the other asyncTask, even if I tried to open it from onProgressUpdate()-which it is supposed to be able to run ui thread components):
private void startConnectingRoutine()
{
Thread t = new Thread()
{
#Override
public void run()
{
Log.d("ConnectingRoutine", "Started connecting routine.");
while(true)
{
if(!connected)
{
startListener();
}
try {
sleep(CONNECTION_CHECK_TIME_MS);
} catch (InterruptedException e) {
Log.e("Intrerrupted", e.toString());
}
}
}
};
t.start();
}
Listener thread:
private void startListener()
{
new Listener().execute();
}
.
private class Listener extends AsyncTask<Long, String, Long>
{
#Override
protected Long doInBackground(Long... params) {
Log.d("Connecting...", "Connecting...");
JSONObject info = new JSONObject();
String receivedMessage;
try {
info.put("Name", user.GetName());
info.put("PORT", MY_PORT);
info.put("IPv4", getIpAddress());
} catch (JSONException e1) {
Log.e("JSON", "JSON error: " + e1.toString());
}
try
{
serverSocket = new Socket(SERVER_IP, SERVER_PORT);
dis = new DataInputStream(serverSocket.getInputStream());
dos = new DataOutputStream(serverSocket.getOutputStream());
dos.writeUTF(info.toString());
dos.flush();
String response = dis.readUTF();
if(response.equals("connected"))
{
Log.d("Connect", "Connected!");
connected = true;
}
else
Log.d("Connect", "Failed to connect!");
while(connected)
{
receivedMessage = dis.readUTF();
publishProgress(receivedMessage);
}
}
catch(Exception e)
{
Log.d("Connect", "Failed to connect");
Log.e("Connect", e.toString());
return null;
}
return null;
}
#Override
protected void onProgressUpdate(String... values) {
super.onProgressUpdate(values);
displayNewMessage(new MMessage(values[0], MMessage.MessageType.Received));
}
#Override
protected void onPostExecute(Long result) {
super.onPostExecute(result);
connected = false;
try{
if(serverSocket != null)
serverSocket.close();
if(dis != null)
dis.close();
if(dos != null)
dos.close();
}catch(Exception e)
{
Log.e("Listener", "There was a problem closing the connection: " + e.toString());
}
}
}
There are perhaps multiple things going wrong here, but two that jump out are:
You're calling DisplayNewMessage() from outside the UI thread.
You're not notifying the adapter that its dataset has changed.
I urge you to look in to better mechanisms for executing tasks in the background than simply creating a Thread. Using AsyncTasks would be a good start, but you'll need to take special care to handle tasks between configuration changes (such as rotating the device).
Furthermore, your code is very difficult to read as you capitalize your method names. This is against Java code conventions. You will make things easier for yourself by formatting your code neatly (a good IDE helps with that) and learning to follow conventions!