Runtime.exec output lost when executing ftp.

Question

I'm writing application, which can execute command line scripts.
I'm executing Runtime.exec("cmd") and then writing commands into output stream. I'm continously reading from input and error stream, so that's not the case.
Everything goes fine while I'm executing simple commands, like: dir, cd.
The problem begins when I try to execute more sophisticated commands, like ftp.
Here is the scenario:
ftp server_nameFtp asks for user name
userAfter providing user name, the output is lost. There are no more characters in InputStream ever. The application doesn't hangs, because ftp actually performs next commands (password, cd, get file). It is just output that isn't shown.
Is it known problem or am I doing something wrong?
Please, help.

Answer 1

I post some code:
import java.util.*;
import java.io.*;
class StreamGobbler extends Thread
    InputStream is;
    String type;
    char[] buf = new char[1000];
    StreamGobbler(InputStream is, String type)
        this.is = is;
        this.type = type;
    public void run()
        try
            InputStreamReader isr = new InputStreamReader(is);
            BufferedReader br = new BufferedReader(isr);
            String line=null;
            boolean write = false;
            while (true) {
                 StringBuffer buffer = new StringBuffer();
                 while (br.ready()) {
                      int chars = br.read(buf, 0, 1000);
                      buffer.append(buf, 0 ,chars);
                      write = true;
                 if (write) {
                      System.out.print(type + ">" + buffer.toString());
                      System.out.flush();
                      write = false;
                try {
                         Thread.sleep(1000);
                    } catch (InterruptedException e) {
                         // TODO Auto-generated catch block
                         e.printStackTrace();
            } catch (IOException ioe)
                ioe.printStackTrace(); 
class StreamForward extends Thread
    InputStream is;
    OutputStream os;
    StreamForward(InputStream is, OutputStream os)
        this.is = is;
        this.os = os;
    public void run()
        try
            InputStreamReader isr = new InputStreamReader(is);
            BufferedReader br = new BufferedReader(isr);
            OutputStreamWriter wr = new OutputStreamWriter(os);
            String line=null;
            while ( (line = br.readLine()) != null) {
                wr.write(line+"\n");
                wr.flush();
            } catch (IOException ioe)
                ioe.printStackTrace(); 
public class GoodWindowsExec
    public static void main(String args[])
        try
            String osName = System.getProperty("os.name" );
            String cmd = new String();
            System.out.println("OS: "+osName);
            if( osName.equals( "Windows NT" ) || osName.equals("Windows XP"))
                cmd = "cmd.exe" ;
            else if( osName.equals( "Windows 95" ) )
                cmd = "command.com" ;
            Runtime rt = Runtime.getRuntime();
            System.out.println("Execing " + cmd);
            Process proc = rt.exec(cmd);
            // any error message?
            StreamGobbler errorGobbler = new
                StreamGobbler(proc.getErrorStream(), "ERROR");           
            // any output?
            StreamGobbler outputGobbler = new
                StreamGobbler(proc.getInputStream(), "OUTPUT");
            StreamForward forward = new
                 StreamForward(System.in, proc.getOutputStream());
            // kick them off
            errorGobbler.start();
            outputGobbler.start();
            forward.start();
            // any error???
            int exitVal = proc.waitFor();
            System.out.println("ExitValue: " + exitVal);       
        } catch (Throwable t)
            t.printStackTrace();
}This is example code, which demonstrate this problem.
It creates new cmd process and forwards to it standard input. Process output and error streams are displayed on standard output.
Basically you can execute dos commands by entering them from keyboard.
Try:
dir
cd something
etc.
Now, to show a problem try:
ftp your_favorite_server
The program should ask for username. Enter username. Nothing is displayed. Notice that ftp is still running and executing commands, but doesn't display any output.
Any clue, why this is happening?