How to start an external program inside a java program

Question

I am new in how to start a program inside another java program! and i don't know how to call it. The 1st question is that i must do it inside a new thread? the second question is how to call the new program. The program i want to call is "wondershaper". I use ubuntu 12.04 for running this programm and in command line i write. "sudo wondershaper eth0 10000 1000". How i can write it inside a general program? I have a server that i want to handle the rate of it! thats why i use it. So i have a multithread server and the code is

class Client extends Thread {
    private Socket connectionSocket;


    public Client(Socket c) throws IOException {
        connectionSocket = c;
    }

    public void run() {

        String path = "C:/pao/new2/";

        File folder = new File(path);
        File[] listOfFiles = folder.listFiles();


        try {

            String fileToSendStr = readFile();
            File fileToSend = null;
            for (File f : listOfFiles)

            {               
                if (f.getName().equals(fileToSendStr)) {
                    fileToSend = f;
                    break;
                }
            }
            //System.out.println("Connescting to Client to recieve the part " +fileToSendStr);
            if (fileToSend == null) {

            }
            System.out.println("Sending the chunk to Client " + fileToSendStr + "to the client: " +connectionSocket.getRemoteSocketAddress().toString());
            java.util.Date date= new java.util.Date();
             System.out.println(new Timestamp(date.getTime()));
            long length = fileToSend.length();
            byte [] longBytes = new byte[8];
            ByteBuffer bbuffer = ByteBuffer.wrap(longBytes);
            bbuffer.putLong(length);
            connectionSocket.getOutputStream().write(longBytes);

            BufferedOutputStream bout = new BufferedOutputStream(connectionSocket.getOutputStream());
            BufferedInputStream bain = new BufferedInputStream(new FileInputStream(fileToSend));

            byte buffer [] = new byte [1024];
            int i = 0;
            while((i = bain.read(buffer, 0, 1024)) >= 0){

                bout.write(buffer, 0, i);


            }



            System.out.println("chunk sended");
            java.util.Date date1= new java.util.Date();
             System.out.println(new Timestamp(date1.getTime()));
            bout.close();
            bain.close();


        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    private String readFile() throws IOException {

        BufferedReader r = new BufferedReader(new InputStreamReader(
                connectionSocket.getInputStream()));
        return r.readLine();

    }
}

so when i read the readFile what client send to me. After if it is the rate string to start the "wondershaper" and put the rate inside the "sudo wondershaper eth0 10000 rate" and start the program

I'm not 100% sure, but I guess you're looking for Java's Process class. — D.R., Jul 23 '13 at 19:37
Related question: http://stackoverflow.com/questions/3643939/java-process-with-input-output-stream — Vitaly Olegovitch, Jul 23 '13 at 19:41

Ankit · Accepted Answer · 2013-07-23T20:05:47.337

1

Process aProcess = Runtime.getRuntime().exec("cmd"); //you can pass any process here

you can also read the output of this program.

InputStream is = aProcess.getInputStream();

Ps: You can pass any process, along with the arguments, but you can't pass things like >>, 2> or | or wild cards like *

-- from the comments

edited Jul 23 '13 at 20:05

answered Jul 23 '13 at 19:37

Ankit

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You can pass any process, but you can't pass things like `>>`, `2>` or `|` – Vitaly Olegovitch Jul 23 '13 at 19:40
Yes, the Runtime class is quite important to learn, and very useful in many cases dealing with console scenarios – user2277872 Jul 23 '13 at 19:43
@VitalijZadneprovskij you can pass, if it is supported by shell. – Ankit Jul 23 '13 at 19:44
but except wild cards chars – Ankit Jul 23 '13 at 19:45
@ay89 I have tried on a Linux environment and it did not work. They were considered as arguments to pass to the process to call. Maybe in that case you have to use `bash cmd arg1 arg2 argN >> output.txt` – Vitaly Olegovitch Jul 23 '13 at 20:01
@VitalijZadneprovskij ok if you have tested, i have just tested '>' not the other. i have added that to answer. – Ankit Jul 23 '13 at 20:04
Let me ask you something! when i start the program it asks me the code in command line that i have in ubuntu! how i can stop it? – Chris Bour Jul 24 '13 at 11:55

How to start an external program inside a java program

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