application.cpp

/* Includes ------------------------------------------------------------------*/  
#include "application.h"

TCPClient client;
byte server[] = { 10, 0, 0, 40 }; // PUT YOUR SERVER'S IP HERE!
void setup()
{
    // Make sure your Serial Terminal app is closed before powering your Core
    Serial.begin(9600);
    // Now open your Serial Terminal, and hit any key to continue!
    while(!Serial.available()) SPARK_WLAN_Loop();

    Serial.println("connecting...");

    if (client.connect(server, 6000))
    {
        Serial.println("connected");
        client.println("Hello from the SparkCore!");
    }
    else
    {
        Serial.println("connection failed");
    }
}

void loop()
{
    if (client.available())
    {
        char c = client.read();
        Serial.print(c);
    }

    if (!client.connected())
    {
        Serial.println();
        Serial.println("disconnecting.");
        client.stop();
        for(;;) SPARK_WLAN_Loop();
    }
}

SimpleJavaServer.java

package simplejavaserver;

import java.net.*;
import java.io.*;

public class SimpleJavaServer extends Thread
{
    private ServerSocket serverSocket;

    public SimpleJavaServer(int port) throws IOException
    {
        serverSocket = new ServerSocket(port);
        //serverSocket.setSoTimeout(10000); // By commenting out the timeout the server will wait for the client forever!
    }

    public void run()
    {
        while(true)
        {
            try
            {
                // Let the user know we are waiting for a client
                System.out.println("Waiting for client on " + 
                        Inet4Address.getLocalHost().getHostAddress() + ":" + 
                serverSocket.getLocalPort() + "...");
                
                // Wait for a new client. Hang until a new one connects
                Socket server = serverSocket.accept();
                //DataInputStream in = new DataInputStream(server.getInputStream());
                BufferedReader din = new BufferedReader(new InputStreamReader(server.getInputStream()));
                DataOutputStream out = new DataOutputStream(server.getOutputStream());
                
                // Let the user know we have accepted a client
                System.out.println("Just connected to " + server.getRemoteSocketAddress());
                
                // Let the user know what the client sent
                System.out.print("Client: ");
                System.out.println(din.readLine());
                
                // Send the welcome message to the client
                System.out.println("Sending welcome messsage");
                out.writeChars("Thank you for connecting to " + server.getLocalSocketAddress() + "\nGoodbye!");
                
                // Close the connection the client so we can listen for new cients
                server.close();
            }catch(SocketTimeoutException s)
            {
                System.out.println("Socket timed out!");
                break;
            }catch(IOException e)
            {
                e.printStackTrace();
                break;
            }
        }
    }
    public static void main(String [] args)
    {
        int port = 6000;
        try
        {
            Thread t = new SimpleJavaServer(port);
            t.start();
        }catch(IOException e)
        {
            e.printStackTrace();
        }
    }
}