Downloading txt file from ftp server

Question

I'm trying to download a simple txt file from a FTP-Server for quite some time now.

I'm using this code:

 String server = "ftp.server.com";
    int port = 21;
    String user = "user";
    String pass = "pass";

    FTPClient ftpClient = new FTPClient();
    try {

        ftpClient.connect(server, port);
        ftpClient.login(user, pass);
        ftpClient.enterLocalPassiveMode();
        ftpClient.setFileType(FTP.BINARY_FILE_TYPE);

        String remoteFile1 = "/test.txt";
        File downloadFile1 = new File(Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator + "test.txt");
        OutputStream outputStream1 = new BufferedOutputStream(new FileOutputStream(downloadFile1));
        boolean success = ftpClient.retrieveFile(remoteFile1, outputStream1);
        outputStream1.close();

        if (success) {
            System.out.println("File #1 has been downloaded successfully.");
        }

    } catch (IOException ex) {
        System.out.println("Error: " + ex.getMessage());
        ex.printStackTrace();
    } finally {
        try {
            if (ftpClient.isConnected()) {
                ftpClient.logout();
                ftpClient.disconnect();
            }
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

But Android studio throws an error at me:

02-27 17:40:31.106  15373-15373/.upload_file_sample E/AndroidRuntime﹕ FATAL EXCEPTION: main
android.os.NetworkOnMainThreadException
        at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1118)
        at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
        at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
        at java.net.InetAddress.getByName(InetAddress.java:289)
        at org.apache.commons.net.SocketClient.connect(SocketClient.java:203)
        at .upload_file_sample.MainActivity.DownloadDatabase(MainActivity.java:104)
        at .upload_file_sample.MainActivity$2.onClick(MainActivity.java:89)
        at android.view.View.performClick(View.java:4232)
        at android.view.View$PerformClick.run(View.java:17298)
        at android.os.Handler.handleCallback(Handler.java:615)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4921)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1027)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)
        at dalvik.system.NativeStart.main(Native Method)

And I can't find out why. I doublechecked my FTP login data, but they are correct. I'm using the apache-commons-net library btw. Can anybody help me out here?

score 2 · Accepted Answer · edited May 23 '17 at 12:31

2

Add your code inside the asynctask. Always make sure you don't make api call in main thread. Check this for asyntask example

AsyncTask Android example

edited May 23 '17 at 12:31

Community

1
1

answered Feb 27 '15 at 17:05

Fahim

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Oh I see, thank you. So am I guessing right that the connection with the ftp server takes too much time so that the main thread is "waiting too long"? I donwloaded the file now, and I see it on my phone, but if I plug the phone to my PC and browse it via USB the file doesn't appear. Do you know why? – Ihara Feb 27 '15 at 17:14
From main thread you cannot make api call. It has to be called from different thread – Fahim Feb 27 '15 at 17:19
Ok :) And why can't I see the file on my PC? – Ihara Feb 27 '15 at 17:21
Did you downloaded file using asynctask? – Fahim Feb 27 '15 at 17:25
yes the error disappeared and when I browse my phone with a filebrowser app I can see it, but when I plug it in with my USB cable I can't see the file on the phone – Ihara Feb 27 '15 at 17:26
http://www.ajaxapp.com/2009/02/21/a-simple-java-ftp-connection-file-download-and-upload/ refer this link for file download – Fahim Feb 27 '15 at 17:35

score 0 · Answer 2 · answered Feb 27 '15 at 17:10

FATAL EXCEPTION: main android.os.NetworkOnMainThreadException

Networking task must not run in main thread, so you must put your task into a new thread.

new Thread(new Runnable() {

    @Override
    public void run() {
        // Your code
    }
}).start();

Downloading txt file from ftp server

2 Answers2