ShareIt如何在PC上工作？

Question

Well,I am trying to build a software like ShareIt but it seems like I am struck in between. What I had done till now- I had made a program(server and client side) where a server can send any kind of file to the client,and for this the client must have the IP address of the server. But I would like to know- How the client can automatically search the IP address of the server which is listening? I don't want to manually enter the IP address each time,instead how the client automatically detect all the IP addresses of the servers which are available and are listening? Thanks in advance.

Answer 1

Once client is connected to an Access Point created, you can get Access Point IP address as below.

public static String getAccessPointIpAddress(Context context) {
    WifiManager wifiManager = (WifiManager) context.getSystemService(WIFI_SERVICE);
    DhcpInfo dhcpInfo = wifiManager.getDhcpInfo();
    byte[] ipAddress = convert2Bytes(dhcpInfo.serverAddress);
    try {
        String ip = InetAddress.getByAddress(ipAddress).getHostAddress();
        return ip.replace("/", "");
    } catch (UnknownHostException e) {
        e.printStackTrace();
    }
    return null;
}

private static byte[] convert2Bytes(int hostAddress) {
    byte[] addressBytes = {(byte) (0xff & hostAddress),
            (byte) (0xff & (hostAddress >> 8)),
            (byte) (0xff & (hostAddress >> 16)),
            (byte) (0xff & (hostAddress >> 24))};
    return addressBytes;
}

Sender/Receiver whoever creates an Access point starts the ServerSocket on its IP address as Hostname. But the client needs a PORT number a well, you can either hardcode it both sides or encode SSID to embed port number on it.

Also I've made an attempt to write a library called SHAREthem to help with File Sharing & transfer or in other words it simulates how SHAREit works. Also this blog explains implementation details Hope it helps.