VisClient/org/hfbk/vis/mcp/VisMCP.java

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package org.hfbk.vis.mcp;

import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.List;
import java.awt.Panel;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketAddress;
import java.net.SocketTimeoutException;
import java.util.concurrent.CopyOnWriteArrayList;

import org.hfbk.util.ShellPanel;
import org.hfbk.util.UIUtils;
import org.hfbk.vis.ImageLoader;

public class VisMCP {

        Frame frame=new Frame("Vis/MCP"); //main window
        
        
        static int clientport = 7778, sendport=7777, TIMEOUT=1000;  
        DatagramSocket socket = null;
        DatagramPacket paket = null;
        
        CopyOnWriteArrayList<SocketAddress> clients=new CopyOnWriteArrayList<SocketAddress>();
        
        
        final List clientLister=new List(5); //the UI list
        
        public VisMCP() {
                frame.setIconImage(ImageLoader.getRessourceImage("icons/vis.png"));                     
                frame.addWindowListener(new WindowAdapter(){
                        public void windowClosing(WindowEvent e) {
                                System.exit(0);
                        }
                });
                
                //try to open the udp port..
                try {
                        paket = new DatagramPacket(new byte[4096], 4096);
                        socket = new DatagramSocket(sendport);
                        socket.setSoTimeout(TIMEOUT);
                } catch (IOException e) {
                        System.err.println("Ausnahmefehler: " + e);
                }               
                
                //build a Pinger to frequently check client availabilty. 
                new Pinger(){
                        //we override pinged to maintain the active client list.
                        void pinged(java.util.List<SocketAddress> clientsFound) {
                                //we add & remove instead of completely replace
                                //to keep currently UI list selected items
                                
                                //add new found clients
                                for (SocketAddress client: clientsFound)
                                        if(!clients.contains(client)){
                                                clients.add(client);
                                                clientLister.add(client.toString());
                                                clientLister.select(clientLister.getItemCount()-1);
                                        }                               
                                //remove lost clients
                                for(SocketAddress client: clients){
                                        if (!clientsFound.contains(client)){
                                                clients.remove(client);
                                                clientLister.remove(client.toString());
                                        }
                                }
                        }
                };              
                
                frame.add(buildPanel());        
                frame.pack();
                UIUtils.blackify(frame); //the finest vis look..
                frame.setVisible(true);                 
        }
        
        Panel buildPanel(){
                Panel p=new ShellPanel(){
                        public String action(String command) {
                                return dispatch(command);
                        }
                };
                
                clientLister.setMultipleMode(true);             
                p.add(clientLister, BorderLayout.NORTH);
                                
                return p;
        }
        
        String dispatch(String command){
                if (clients.size()==0) return "Error: No client visible.";
                
                byte[] data=command.getBytes(); //extract command string as bytes

                String result="";
                
                for (SocketAddress client: clients)  
                        if(clientLister.isIndexSelected(clients.indexOf(client))){ //if a client is UI list selected.. 
                                result+="\n "+client+": ";
                                try {
                                        socket.send(new DatagramPacket(data, data.length, client));
                                        socket.receive(paket);
                                        result+=new String(paket.getData(), 0, paket.getLength());
                                } catch (Exception e) { //timeout if client doesn't respond. 
                                        if (e instanceof SocketTimeoutException) result+="No answer.";
                                        else throw new RuntimeException (e);
                                }
                        }
                return result;
        }
        
        public static void main(String[] args) {
                new VisMCP();
        }
}

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