Question

I would like to run a Dos program from a web server. The Dos program has to be run interactively as the user interface is via a series of questions and answers. The answer to one question will determine the next question. I will have to use ajax on the web server, but I think I can do that.

I found one java program on Stackoverflow which seems to do something similar to what I want. However when I compile the program I get an error ie.

javac PipeRedirection.java 
PipeRedirection.java:43: package InputProcess does not exist
                    InputProcess.Gobbler outGobbler = new InputProcess.Gobbler(p.getInputStream());

The stack overflow question url was

How can I write large output to Process getOutputStream?

The Java file was

/* 
 ####### PipeRedirection.java 
*/

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

public class PipeRedirection {

public static void main(String[] args) throws FileNotFoundException {

    if(args.length < 2) {
            System.err.println("Need at least two arguments");
            System.exit(1);
    }

    try {
            String input = null;
            for(int i = 0; i < args.length; i++) {

                    String[] commandList = args[i].split(" ");

                    ProcessBuilder pb = new ProcessBuilder(commandList);
                    //pb.redirectErrorStream(true);
                    Process p = pb.start();

                    if(input != null) {
                            PrintWriter writer = new PrintWriter(new OutputStreamWriter(new BufferedOutputStream(p.getOutputStream())), true);
                            writer.println(input);
                            writer.flush();
                            writer.close();
                    }

                    InputProcess.Gobbler outGobbler = new InputProcess.Gobbler(p.getInputStream());
                    InputProcess.Gobbler errGobbler = new InputProcess.Gobbler(p.getErrorStream());
                    Thread outThread = new Thread(outGobbler);
                    Thread errThread = new Thread(errGobbler);
                    outThread.start();
                    errThread.start();

                    outThread.join();
                    errThread.join();

                    int exitVal = p.waitFor();
                    System.out.println("\n****************************");
                    System.out.println("Command: " + args[i]);
                    System.out.println("Exit Value = " + exitVal);
                    List<String> output = outGobbler.getOuput();
                    input = "";
                    for(String o: output) {
                            input += o;
                    }
            }
            System.out.println("Final Output:");
            System.out.println(input);

    } catch (IOException ioe) {
            // TODO Auto-generated catch block
            System.err.println(ioe.getLocalizedMessage());
            ioe.printStackTrace();
    } catch (InterruptedException ie) {
            // TODO Auto-generated catch block
            System.err.println(ie.getLocalizedMessage());
            ie.printStackTrace();
    }

}


public static class Gobbler implements Runnable {
    private BufferedReader reader;
    private List<String> output;

    public Gobbler(InputStream inputStream) {
            this.reader = new BufferedReader(new InputStreamReader(inputStream));
    }

    public void run() {
            String line;
            this.output = new ArrayList<String>();
            try {
                    while((line = this.reader.readLine()) != null) {
                            this.output.add(line + "\n");
                    }
                    this.reader.close();
            }
            catch (IOException e) {
                    // TODO
                    System.err.println("ERROR: " + e.getMessage());
            }
    }

    public List<String> getOuput() {
            return this.output;
    }
}
}

Does anyone know why I get the compile error? Can I substitute some other code for InputProcess?

Thanks for any help

Peter

Answer 1

I think it’s pretty obvious that you’re missing parts to this code. A package named InputProcess which has a class called Gobbler was not included in the OP’s post. Probably because it was not relevant to their question.

The error message essentially says that it can not find this package/code that it is looking for.

What this class does exactly, only the OP can tell you. At its most basic, though, it appears to read from an InputStream and convert it to a List<String>. I would read up on Java IO and try to replicate similar functionality.

Edit:

Looks like the Gobbler class is indeed included in the example above. Remove the InputProcess package name from your code (or put the Gobbler class in an InputProcess package) and you should be good to go.