java - 如何在Android上获取本地网络中所有设备的IP地址和名称

Question

我想用 java 查看我网络上所有连接的设备，但我无法让它工作。我在下面附上了一些屏幕截图，说明我希望如何输出它。我想要名称(例如“TP Link Router”或“Nexus 5X”)和 IP 地址。

我在 google 和 stackoverflow 上搜索了很多，但似乎没有什么适合我的。甚至 GitHub 也没有有效的代码。我尝试搜索 UPnP、局域网、子网等，但一无所获。

InetAddress localhost = InetAddress.getLocalHost();
byte[] ip = localhost.getAddress();
for (int i = 1; i <= 254; i++) {
    ip[3] = (byte)i;
    InetAddress address = InetAddress.getByAddress(ip);
    if (address.isReachable(1000)) {
        System.out.println(address + address.getHostAddress() + address.getAddress() + address.getHostName() + address.getCanonicalHostName());
    }
}

我确实找到了一个重复的(某种程度上的)问题，但是一年多了都没有得到回答。 Source

Answer 1

主要问题是您获取了错误的 IP 地址。 InetAddress.getLocalHost() 返回 127.0.0.1，那只是您的设备。

改为使用 Wifi IP 地址:

ConnectivityManager cm = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
WifiManager wm = (WifiManager)context.getSystemService(Context.WIFI_SERVICE);

WifiInfo connectionInfo = wm.getConnectionInfo();
int ipAddress = connectionInfo.getIpAddress();
String ipString = Formatter.formatIpAddress(ipAddress);

这是一个快速而肮脏的 AsyncTask 可以做到这一点:

static class NetworkSniffTask extends AsyncTask<Void, Void, Void> {

  private static final String TAG = Constants.TAG + "nstask";

  private WeakReference<Context> mContextRef;

  public NetworkSniffTask(Context context) {
    mContextRef = new WeakReference<Context>(context);
  }

  @Override
  protected Void doInBackground(Void... voids) {
    Log.d(TAG, "Let's sniff the network");

    try {
      Context context = mContextRef.get();

      if (context != null) {

        ConnectivityManager cm = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
        WifiManager wm = (WifiManager)context.getSystemService(Context.WIFI_SERVICE);

        WifiInfo connectionInfo = wm.getConnectionInfo();
        int ipAddress = connectionInfo.getIpAddress();
        String ipString = Formatter.formatIpAddress(ipAddress);


        Log.d(TAG, "activeNetwork: " + String.valueOf(activeNetwork));
        Log.d(TAG, "ipString: " + String.valueOf(ipString));

        String prefix = ipString.substring(0, ipString.lastIndexOf(".") + 1);
        Log.d(TAG, "prefix: " + prefix);

        for (int i = 0; i < 255; i++) {
          String testIp = prefix + String.valueOf(i);

          InetAddress address = InetAddress.getByName(testIp);
          boolean reachable = address.isReachable(1000);
          String hostName = address.getCanonicalHostName();

          if (reachable)
            Log.i(TAG, "Host: " + String.valueOf(hostName) + "(" + String.valueOf(testIp) + ") is reachable!");
        }
      }
    } catch (Throwable t) {
      Log.e(TAG, "Well that's not good.", t);
    }

  return null;
}

权限如下:

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

并非所有路由器都允许这样做，因此以其他方式获取名称是将 mac 地址发送到 api，然后返回品牌名称。

String macAdress = "5caafd1b0019";
String dataUrl = "http://api.macvendors.com/" + macAdress;
HttpURLConnection connection = null;
try {
    URL url = new URL(dataUrl);
    connection = (HttpURLConnection) url.openConnection();
    connection.setRequestMethod("POST");
    connection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
    connection.setDoInput(true);
    connection.setDoOutput(true);
    DataOutputStream wr = new DataOutputStream(connection.getOutputStream());
    wr.flush();
    wr.close();
    InputStream is = connection.getInputStream();
    BufferedReader rd = new BufferedReader(new InputStreamReader(is));
    StringBuffer response = new StringBuffer();
    String line;
    while ((line = rd.readLine()) != null) {response.append(line);response.append('\r');}
    rd.close();
    String responseStr = response.toString();
    Log.d("Server response", responseStr);
} catch (Exception e) {e.printStackTrace();} finally {if (connection != null) {connection.disconnect();}}