android-監聽wifi狀态和信号強度變化

// /
  // 監聽網絡網絡狀态變化

  private MyReceiver mMyReceiver;
  private final String NETWORK_STATE_CHANGE = "android.net.conn.CONNECTIVITY_CHANGE";

  private void registReceiver() {
    if (mMyReceiver != null)
      return;
    mMyReceiver = new MyReceiver();
    IntentFilter filter = new IntentFilter();
    filter.addAction(NETWORK_STATE_CHANGE);
    filter.addAction(WifiManager.WIFI_STATE_CHANGED_ACTION);
    filter.addAction(WifiManager.RSSI_CHANGED_ACTION);
    registerReceiver(mMyReceiver, filter);
  }

  private void unregisterReceiver() {
    if (mMyReceiver == null)
      return;
    unregisterReceiver(mMyReceiver);
    mMyReceiver = null;
  }

  int[] wifiStateImgs = new int[] { R.drawable.selector_wifi_1,
      R.drawable.selector_wifi_2, R.drawable.selector_wifi_3,
      R.drawable.selector_wifi_4 };

  private class MyReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
      String action = intent.getAction();
      Logcat.d(TAG, "action: " + action);
      if (action.equals(NETWORK_STATE_CHANGE)) {
        boolean isNetOK = NetHelper
            .isNetworkAvailable(MainActivity.this);
        Logcat.d(TAG, "網絡狀态發生變化,是否可用：" + isNetOK);
        if (isNetOK) {
          initWifiState();
        } else {
          btnWifi.setBackgroundResource(R.drawable.selector_wifi_0);
        }

      } else if (action.equals(WifiManager.WIFI_STATE_CHANGED_ACTION)) {
        int wifistate = intent.getIntExtra(
            WifiManager.EXTRA_WIFI_STATE,
            WifiManager.WIFI_STATE_DISABLED);

        if (wifistate == WifiManager.WIFI_STATE_DISABLED) {
          btnWifi.setBackgroundResource(R.drawable.selector_wifi_0);
        } else if (wifistate == WifiManager.WIFI_STATE_ENABLED) {
          updateWifiStrength();
        }
      } else if (action.equals(WifiManager.RSSI_CHANGED_ACTION)) {
        initWifiState();
      }
    }
  }

  public int getStrength(Context context) {
    WifiManager wifiManager = (WifiManager) context
        .getSystemService(Context.WIFI_SERVICE);
    WifiInfo info = wifiManager.getConnectionInfo();
    if (info.getBSSID() != null) {
      int strength = WifiManager.calculateSignalLevel(info.getRssi(), 4);
      // 連結速度
      // int speed = info.getLinkSpeed();
      // // 連結速度機關
      // String units = WifiInfo.LINK_SPEED_UNITS;
      // // Wifi源名稱
      // String ssid = info.getSSID();
      return strength;

    }
    return 0;
  }

  public void initWifiState() {

    ConnectivityManager manager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo info = manager
        .getNetworkInfo(ConnectivityManager.TYPE_WIFI);
    Logcat.d(TAG, "info.isConnected(): " + info.isConnected());
    if (info.isConnected()) {
      updateWifiStrength();
    } else {
      btnWifi.setBackgroundResource(R.drawable.selector_wifi_0);
    }
  }

  public void updateWifiStrength() {
    int strength = getStrength(this);
    if (strength >= 0 && strength <= 3)
      btnWifi.setBackgroundResource(wifiStateImgs[strength]);
    Logcat.d(TAG, "wifi strength: " + strength);
  }