Android - find a server in the network

问题

I am currently writing a client-server application and I ask myself if there is a better way to find a server in the local network then going trough all the available IP addresses and see if the correct answer is supplied?

回答1:

You might want to look into UDP broadcasts, where your server announces itself and the phone listens for the broadcasts.

There is an example from the Boxee remote project, quoted below.

Getting the Broadcast Address

You need to access the wifi manager to get the DHCP info and construct a broadcast address from that:

InetAddress getBroadcastAddress() throws IOException {
    WifiManager wifi = mContext.getSystemService(Context.WIFI_SERVICE);
    DhcpInfo dhcp = wifi.getDhcpInfo();
    // handle null somehow

    int broadcast = (dhcp.ipAddress & dhcp.netmask) | ~dhcp.netmask;
    byte[] quads = new byte[4];
    for (int k = 0; k < 4; k++)
      quads[k] = (byte) ((broadcast >> k * 8) & 0xFF);
    return InetAddress.getByAddress(quads);
}

Sending and Receiving UDP Broadcast Packets

Having constructed the broadcast address, things work as normal. The following code would send the string data over broadcast and then wait for a response:

DatagramSocket socket = new DatagramSocket(PORT);
socket.setBroadcast(true);
DatagramPacket packet = new DatagramPacket(data.getBytes(), data.length(),
    getBroadcastAddress(), DISCOVERY_PORT);
socket.send(packet);

byte[] buf = new byte[1024];
DatagramPacket packet = new DatagramPacket(buf, buf.length);
socket.receive(packet);

You could also look into Bonjour/zeroconf, and there is a Java implementation that should work on Android.

来源：https://stackoverflow.com/questions/4464207/android-find-a-server-in-the-network

标签

android

networking

network-programming