android平板电脑，路由器和2个设备之间的单向连接

Question

I've got question, that I haven't found answer for yet. I have 2 devices with wifi each, that are sending special data. I want to show this data at the same moment on a tablet. There is a router with network, both tablet and that devices are connected to this network.

How to solve this? Should I use serversocket? I don't know if I explained it clear enought, if not, please ask. Thanks for any response.

Answer 1

I have the same application running on the company I work. The "device" is a micro-controller based device that is implemented the lwIP (lightweight IP protocol) and it's listening to the port 83 and every 500ms the tablet goes and read new fresh data and plot it in a graph. Works like a charm.

(in case you'll be plotting charts, I used the AChartEngine and you can check on my profile a question/answer on it with some useful info)

the code below is a simplified version of what I'm doing. The complete version includes SEVERAL try{ } catch() { } in case it catches an exception it try closing the socket and return null;

public static String SendMessage(String message, String ip, int port) {

    // Connect to host ==================================
    Socket socket = new Socket();
    socket.setSoTimeout(TIMEOUT);
    InetSocketAddress addr = new InetSocketAddress(ip, port);
    socket.connect(addr, TIMEOUT);

    // Send Message ======================================
    byte[] outputBuffer = message.getBytes();
    socket.getOutputStream().write(outputBuffer);

    // Zero the input buffer =============================
    for (int i = 0; i < inputBuffer.length; i++) {
        inputBuffer[i] = 0;
    }

    // Read the response ==================================
    int count = 0;
    do {
        count = socket.getInputStream().read(inputBuffer);
    } while (count != -1);

    // Close connection ====================================
    close(socket);

    // Return message ======================================
    return new String(inputBuffer).trim();
}

hope it helps, happy coding.

Answer 2

1. Socket will be a good idea.

For Sending :

Socket s = new Socket();
s.connect(new InetSocketAddress("IP_ADDR",PORT_NO);

OutputStream o = s.getOutputStream();
PrintWriter pw = new PrintWriter(o);
pw.write(msg);   // msg will be the data needed to send

For Receiving:

Socket s = new Socket();
s.connect(new InetSocketAddress("IP_ADDR",PORT_NO);

InputStream i = s.getInputStream();
InputStreamReader isr = new InputStreamReader(i);
BufferedReader br = new BufferedReader(isr);
String str = new String();

while((str=br.readLine())!=null){

   System.out.println(str);  // do whatever u want to do with str, the data read


 }