JLine UI for Apache Felix

Apache Felix by default provides a very simple text shell UI. Unfortunately, it is not very convenient to use. For example, it doesn't support command history. JLineTUI is a replacement, which make uses of the wondeful JLine library to provide helpful features like command history etc.

Source Code: JLineTUIActivator.java

package us.timetrack.felix.shell;

import org.apache.felix.shell.ShellService;
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.osgi.util.tracker.ServiceTracker;

public class JLineTUIActivator implements BundleActivator {
 private BundleContext _ctx = null;
 private ServiceTracker _tracker = null; 
 private Thread _thread = null;
 private ShellTUIRunnable _runnable = null;
 
 @Override
 public void start(BundleContext ctx) throws Exception {
  this._ctx = ctx;
  _tracker = new ServiceTracker(_ctx, ShellService.class.getName(), null);
  _tracker.open();
  _runnable = new ShellTUIRunnable(_tracker);
  _thread = new Thread(_runnable);
  _thread.start();
 }

 @Override
 public void stop(BundleContext ctx) throws Exception {
  if(_runnable!=null) _runnable.stop();
  _thread.join();
  _tracker.close();  
 }
}

Source Code: ShellTUIRunnable.java

package us.timetrack.felix.shell;

import java.io.IOException;
import java.io.PrintStream;

import jline.ConsoleReader;

import org.apache.felix.shell.ShellService;
import org.osgi.util.tracker.ServiceTracker;

class ShellTUIRunnable implements Runnable { 
 private static final String PROMPT="$";
 private ServiceTracker _tracker = null;
 private volatile boolean _stop = false;
 private PrintStream _out = null;
 
 ShellTUIRunnable(ServiceTracker tracker){
  this._tracker = tracker;
  this._out = System.out;
 }
 
 void stop(){
  _stop = true;
 }
 
 @Override
 public void run() {
  ConsoleReader reader = openConsoleReader();
  if( reader==null ) return;
  while(!_stop){
   dispatchCommand(readCommandLine(reader));   
  } 
 }

 private void dispatchCommand(String command) {
  if(command==null) return;
  command = command.trim();
  if(command.isEmpty()) return;
  ShellService service = (ShellService)_tracker.getService();
  try {
   service.executeCommand(command, _out, System.err);
  } catch (Exception e) {
   System.err.println("Shell JLine UI: "+e.getMessage());
  }
 }

 private String readCommandLine(ConsoleReader reader) {
  String command = null;
  try{
   command = reader.readLine(PROMPT);
  }catch(IOException exception){
   stop();
   System.err.println("cannot accept command" + exception.getMessage());
  }
  return command;
 }

 private ConsoleReader openConsoleReader() {
  ConsoleReader reader = null;
  try{
   reader = new ConsoleReader();
   reader.setBellEnabled(false);
  }catch(IOException exception){
   System.err.println("cannot open the console to read: " + exception.getMessage());
  }
  return reader;
 }
}