自定义View,指示wifi信号强度(菜鸟历险记)

@RemoteView
public class TextClock extends TextView {
    ...

private final BroadcastReceiver mIntentReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            if (mTimeZone == null && Intent.ACTION_TIMEZONE_CHANGED.equals(intent.getAction())) {
                final String timeZone = intent.getStringExtra("time-zone");
                createTime(timeZone);
            }
            onTimeChanged();
        }
    };

public TextClock(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

      ...
    }
    ...

 @Override
 protected void onAttachedToWindow() {
       super.onAttachedToWindow();

        if (!mAttached) {
            mAttached = true;

            registerReceiver();

       }
    }

@Override
protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();
...
        if (mAttached) {
           unregisterReceiver();
   ...       
           getHandler().removeCallbacks(mTicker);
   ...
        }
   ...
    }
}

wifi的消息一共有五种：

WifiManager.WIFI_STATE_DISABLED: //wifi不可用

WifiManager.WIFI_STATE_DISABLING://wifi 正在关闭或者断开

WifiManager.WIFI_STATE_ENABLED://wifi可用

WifiManager.WIFI_STATE_ENABLING://wifi正在打开或者连接

WifiManager.WIFI_STATE_UNKNOWN://未知消息

仅在wifi状态为WIFI_STATE_ENABLED的时候，才表示wifi已经连接成功。

 /**
     * Calculates the level of the signal. This should be used any time a signal
     * is being shown.
     *
     * @param rssi The power of the signal measured in RSSI.
     * @param numLevels The number of levels to consider in the calculated
     *            level.
     * @return A level of the signal, given in the range of 0 to numLevels-1
     *         (both inclusive).
     */
    public static int calculateSignalLevel(int rssi, int numLevels) {
        if (rssi <= MIN_RSSI) {
            return 0;
        } else if (rssi >= MAX_RSSI) {
            return numLevels - 1;
        } else {
            float inputRange = (MAX_RSSI - MIN_RSSI);
            float outputRange = (numLevels - 1);
            return (int)((float)(rssi - MIN_RSSI) * outputRange / inputRange);
        }
    }

/**
 * Created by frank on 2016/3/27.
 */
public class WifiStateView extends ImageView {


    public static final String TAG = "WifiStateView";
    private static final int LEVEL_DGREE = 4;
    //定义wifi信号等级
    private static final int LEVEL_0 = 0;
    private static final int LEVEL_1 = 1;
    private static final int LEVEL_2 = 2;
    private static final int LEVEL_3 = 3;
    private static final int LEVEL_NONE = -1;

    WifiManager mWifiManager;
    WifiHandler mWifiHandler;
    ConnectivityManager mCM;

    //将handle设定为static，防止内存泄漏
    private static class WifiHandler extends Handler{
        WeakReference<WifiStateView> mView;
        public WifiHandler(WifiStateView view){
            mView = new WeakReference<WifiStateView>(view);

        }
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);

            if(mView.get() == null){
                return;
            }
            WifiStateView view = mView.get();
            Log.i(TAG, "handleMessage level " + msg.what);
            //根据wifi的信号强度等级，更换图标
            switch (msg.what) {
                case LEVEL_0:
                    view.setImageResource(R.drawable.wifi0);
                    break;
                case LEVEL_1:
                    view.setImageResource(R.drawable.wifi1);
                    break;
                case LEVEL_2:
                   view. setImageResource(R.drawable.wifi2);
                    break;

                case LEVEL_3:
                   view. setImageResource(R.drawable.wifi3);
                    break;

                case LEVEL_NONE:
                    view.setImageResource(R.drawable.wifinone);
                    break;

                default:
                    break;
            }
        }

    }


    private BroadcastReceiver mWifiStateReceiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            //WifiManager.WIFI_STATE_CHANGED_ACTION
            Log.i(TAG, "onReceive "+action);
            if (action.equals(WifiManager.WIFI_STATE_CHANGED_ACTION)) {
                //如果wifi没有连接成功，则显示wifi图标无连接的状态
                if (mWifiManager.getWifiState() == WifiManager.WIFI_STATE_DISABLED) {
                    mWifiHandler.sendEmptyMessage(LEVEL_NONE);
                    return;
                }

            }else if(action.equals(ConnectivityManager.CONNECTIVITY_ACTION)){

                NetworkInfo netInfo =  mCM.getActiveNetworkInfo();
                //当前网络无连接，当前网络不是wifi连接,当前网络是wifi但是没有连接，wifi图标都显示无连接
                if(netInfo == null || netInfo.getType() != ConnectivityManager.TYPE_WIFI){
                    mWifiHandler.sendEmptyMessage(LEVEL_NONE);
                }else if(netInfo != null && netInfo.getType() == ConnectivityManager.TYPE_WIFI && !netInfo.isConnected()){
                    mWifiHandler.sendEmptyMessage(LEVEL_NONE);

                }

            }else if(action.equals(WifiManager.RSSI_CHANGED_ACTION)){
                //当信号的rssi值发生变化时，在这里处理
                if (mWifiManager.getWifiState() == WifiManager.WIFI_STATE_DISABLED) {
                    mWifiHandler.sendEmptyMessage(LEVEL_NONE);
                    return;
                }
                WifiInfo info = mWifiManager.getConnectionInfo();
                //计算wifi的信号等级
                int level = WifiManager.calculateSignalLevel(info.getRssi(), LEVEL_DGREE);
                Log.i(TAG,"wifi rssi "+info.getRssi());
                mWifiHandler.sendEmptyMessage(level);
            }
        }
    };

    public WifiStateView(Context context) {
        this(context, null);
    }

    public WifiStateView(Context context, AttributeSet attrs) {
        this(context, null, 0);
    }

    public WifiStateView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

        mWifiManager = (WifiManager) getContext().getSystemService(Context.WIFI_SERVICE);
        mCM = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
        mWifiHandler = new WifiHandler(this);
    }

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        IntentFilter mFilter = new IntentFilter(WifiManager.WIFI_STATE_CHANGED_ACTION);
       // mFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
        mFilter.addAction(WifiManager.RSSI_CHANGED_ACTION);
        //注册广播接收器
        getContext().registerReceiver(mWifiStateReceiver, mFilter);

    }

    @Override
    protected void onDetachedFromWindow() {
        super.onDetachedFromWindow();
        mWifiHandler.removeCallbacksAndMessages(null);
        //注销广播接收器
        getContext().unregisterReceiver(mWifiStateReceiver);
    }


}