RoboSight.java

import java.io.*;
import java.net.*;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.regex.*;
import java.util.HashMap;
import java.util.Scanner;
import java.util.Timer;
import java.util.TimerTask;

public class RoboSight{
    protected String m_url;
    private Timer m_timer;
    private HashMap<String, Float> m_hashmap;
    private ReadWriteLock m_lock;

    public RoboSight(){
        this("http://10.40.9.13/data.html");
    }

    public RoboSight(String url){
        m_url = url;
        m_timer = new Timer();
        m_hashmap = new HashMap<String, Float>();
        m_lock = new ReentrantReadWriteLock();
    }

    private class RoboSightTask extends TimerTask{
        private RoboSight m_roboSight;
        public RoboSightTask(RoboSight roboSight){
            m_roboSight = roboSight;
        }

        @Override
        public void run(){
            String payloadString = httpRequest(m_url);
            parse(payloadString);
        }
    }

    public void start() {
        RoboSightTask task = new RoboSightTask(this);
        m_timer.schedule(task, 0L, 100L);
    }

    public float get(String key){
        m_lock.readLock().lock();
        try{
            if(m_hashmap.containsKey(key)){
                return m_hashmap.get(key);
            }
            else{
                return 0.0f;
            }
        }
        finally{
            m_lock.readLock().unlock();
        }
    }

    private void clear(){
        m_hashmap.clear();
    }

    protected void parse(String input){
        Pattern dataRegex = Pattern.compile("(\\w+) = ([\\d\\.\\-]+)");
        Matcher matcher = dataRegex.matcher(input);
        m_lock.writeLock().lock();
        try{
            clear();
            while(matcher.find()){
                m_hashmap.put(matcher.group(1), Float.parseFloat(matcher.group(2)));
            }
        }
        finally{
            m_lock.writeLock().unlock();
        }
    }

    protected static String httpRequest(String url){
        String output = "";
        try{
            InputStream stream = new URL(url).openStream();
            BufferedReader reader = new BufferedReader(new InputStreamReader(stream));
            StringBuilder response = new StringBuilder();
            String line;
            while((line = reader.readLine()) != null){
                response.append(line);
                response.append("\n");
            }
            reader.close();
            output = response.toString();
        }
        catch (Exception e){
            e.printStackTrace();
        }
        return output;
    }
}