Question

I’ve implemented an example from Apaches’s web: http://commons.apache.org/exec/tutorial.html

What I need now is listen / receive feedback from a heavy process.

I know how to print the process result using setStreamHandler method but this result is displayed once the execution finished.

Answer 1

I suggest you read PumpStreamHandler and InputStreamPumper. You basically want almost exactly these classes. Just modify the InputStreamPumper.run() loop. Instead of os.write(), it should fire your event. To allow the results to start arriving while your process is running, call it as follows:

CommandLine cmdLine = new CommandLine(yourExecutable);
DefaultExecuteResultHandler resultHandler = new DefaultExecuteResultHandler();

Executor executor = new DefaultExecutor();
executor.setStreamHandler(new YourPumpStreamHandler());
executor.execute(cmdLine, resultHandler);
// until waitFor returns, the process is running and events can be generated
int exitValue = resultHandler.waitFor();