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Android 集成Google Cast 异常问题解析

Dai_Dev 人气:0

GoogleCast 异常问题

项目中集成 Google Cast 功能时, 部分机型遇到一些问题

需求

项目中Cast需求有点特别,默认Cast Button处于不可见状态。 APP进入前台时,查询周围是否有可用Cast设备, 有才显示Cast Button, 否则隐藏

根据流程, 我们有两种情况需要处理

Fragment/Activity 启动时查询Available Cast Devices

暂命名方法1

代码实现如下: Fragment -> onResume(), checkCastDevices:

    public static boolean checkCastDevice(Context activity) {
        MediaRouter mediaRouter = MediaRouter.getInstance(activity);
        List<mediarouter.routeinfo> routes = mediaRouter.getRoutes();
        if (routes != null &amp;&amp; routes.size() != 0) {
            for (MediaRouter.RouteInfo info : routes) {
                if (info.getDeviceType() != MediaRouter.RouteInfo.CONNECTION_STATE_DISCONNECTED
                        && !info.isDefault() && !info.isBluetooth() && !info.isDeviceSpeaker()) {
                    return true;
                }
            }
        }
        return false;
    }

Fragment/Activity 处于前台时,动态获取Availabe Cast Devices

暂命名方法2

监听了addCastStateListener CastContext.addCastStateListener(this)

    @Override
    public void onCastStateChanged(int i) {
        stateListenerListTemp.clear();
        stateListenerListTemp.addAll(stateListenerList);
        switch (i) {
            case CastState.CONNECTED:
                for (CastStateListener listener : stateListenerListTemp) {
                    listener.connected();
                }
                break;
            case CastState.CONNECTING:
                for (CastStateListener listener : stateListenerListTemp) {
                    listener.connecting();
                }
                break;
            case CastState.NO_DEVICES_AVAILABLE:  //has not available devices
                for (CastStateListener listener : stateListenerListTemp) {
                    listener.noDevicesAvailable();  // hide cast button
                }
                break;
            case CastState.NOT_CONNECTED:  //has available devices, but not connect
                for (CastStateListener listener : stateListenerListTemp) {
                    listener.notConnected();  // show cast button
                }
                break;
        }
        stateListenerListTemp.clear();
    }

依据上述实现, 可以即时监听Cast Devices的变化,动态更新Cast Button的可见性

问题

新增了一个有个需求, Toolbar上新增了一个视图,需要根据Cast Button的可见性来设置视图可见性,即二者可见性互斥,但在测试中发现一些问题。

部分设备上,例如Remi Note 4, 上述两个方法都无效

分析

当App进程销毁后重新启动, 可以成功获取Cast Devices, 说明初始化CastContext时, 主动扫描了周边Routes, 而App关闭后重新打开, 部分设备未主动扫描, 所以获取状态失败。

当Cast Button可见时,断开WIFI连接, 因为没有收到onCastStateChanged的回调,CastButton.SetVisibility(View.GONE)并未执行, 但是Cast Button 却不可见了, 打开Developers options--Show layouts bounds开关, 发现Cast Button 在布局中存在,但是图标却不可见,那么有两种可能: - Cast Button的Drawable 被移除了 - Cast Button被设为View.INVISIBLE

但是onCastStateChanged的回调并未执行, 但是Cast Button 状态却有变化,那只能说明Cast Button内部监听了连接状态的变化,并内部处理了展示状态。

项目中Cast Button是一个MediaRouteButton, 查询源码

public class MediaRouteButton extends View {
    private static final String TAG = "MediaRouteButton";
    private static ConnectivityReceiver sConnectivityReceiver;
    private int mVisibility = VISIBLE;
    private boolean mAlwaysVisible;
    public MediaRouteButton(Context context) {
        this(context, null);
    }
    public MediaRouteButton(Context context, AttributeSet attrs) {
        this(context, attrs, R.attr.mediaRouteButtonStyle);
    }
    public MediaRouteButton(Context context, AttributeSet attrs, int defStyleAttr) {
        super(MediaRouterThemeHelper.createThemedButtonContext(context), attrs, defStyleAttr);
        if (sConnectivityReceiver == null) {
            sConnectivityReceiver = new ConnectivityReceiver(context.getApplicationContext());
        }
    }
    @Override
    public void onAttachedToWindow() {
        super.onAttachedToWindow();
        sConnectivityReceiver.registerReceiver(this);
    }
    @Override
    public void onDetachedFromWindow() {
        if (!isInEditMode()) {
            sConnectivityReceiver.unregisterReceiver(this);
        }
        super.onDetachedFromWindow();
    }
    void refreshVisibility() {
        //set VISIBLE or INVISIBLE
        super.setVisibility(mVisibility == VISIBLE
                && !(mAlwaysVisible || sConnectivityReceiver.isConnected())
                ? INVISIBLE : mVisibility);
    }
    /**
    * 监听连接状态的变化,刷新MediaRouteButton可见性
    */
    private static final class ConnectivityReceiver extends BroadcastReceiver {
        private final Context mContext;
        // If we have no information, assume that the device is connected
        private boolean mIsConnected = true;
        private List<MediaRouteButton> mButtons;
        ConnectivityReceiver(Context context) {
            mContext = context;
            mButtons = new ArrayList<MediaRouteButton>();
        }
        public void registerReceiver(MediaRouteButton button) {
            if (mButtons.size() == 0) {
                IntentFilter intentFilter = new IntentFilter();
                intentFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
                mContext.registerReceiver(this, intentFilter);
            }
            mButtons.add(button);
        }
        public void unregisterReceiver(MediaRouteButton button) {
            mButtons.remove(button);
            if (mButtons.size() == 0) {
                mContext.unregisterReceiver(this);
            }
        }
        public boolean isConnected() {
            return mIsConnected;
        }
        @Override
        public void onReceive(Context context, Intent intent) {
            final String action = intent.getAction();
            if (ConnectivityManager.CONNECTIVITY_ACTION.equals(action)) {
                boolean isConnected = !intent.getBooleanExtra(
                        ConnectivityManager.EXTRA_NO_CONNECTIVITY, false);
                if (mIsConnected != isConnected) {
                    mIsConnected = isConnected;
                    for (MediaRouteButton button: mButtons) {
                        button.refreshVisibility();
                    }
                }
            }
        }
    }
}

源码中可见,内部定义了ConnectivityReceiver来监听连接状态的变化, 从而内部控制MediaRouteButton的显示。

解决

问题1

App启动时,虽然主动扫描周边Routes,来更新可以Cast Devices状态

    //Init Cast
    public static void initCast(Context context) {
        if (context == null)
            return;
        if (initialized) {
            CastContextManager.getInstance().addRouter(context);
            return;
        }
        initialized = true;
        //初始化CastContextManager
        ....
    }
    public void addRouter(Context context) {
        if(castContext !=null){
            MediaRouter mediaRouter = MediaRouter.getInstance(context);
            mediaRouter.removeCallback(callback);
            mediaRouter.addCallback(MediaRouteSelector.EMPTY, callback, MediaRouter.CALLBACK_FLAG_PERFORM_ACTIVE_SCAN);
        }
    }
    private final MediaRouter.Callback callback = new MediaRouter.Callback() {
        @Override
        public void onProviderAdded(MediaRouter router, MediaRouter.ProviderInfo provider) {
            super.onProviderAdded(router, provider);
            ZenLogger.dd("MXMediaRouter", () -> "onProviderAdded  " + provider.getRoutes());
        }
        @Override
        public void onProviderRemoved(MediaRouter router, MediaRouter.ProviderInfo provider) {
            super.onProviderRemoved(router, provider);
            ZenLogger.dd("MXMediaRouter", () -> "onProviderRemoved  " + provider.getRoutes());
        }
        @Override
        public void onProviderChanged(MediaRouter router, MediaRouter.ProviderInfo provider) {
            super.onProviderChanged(router, provider);
            ZenLogger.dd("MXMediaRouter", () -> "onProviderChanged  " + provider.getRoutes());
        }
    };

问题2

因为无法收到onCastStateChanged的回调, 而且MediaRouteButton内部监听了连接状态的变化来更新显示,那么我们也效仿相同的实现,通过监听当前连接状态,结合MediaRouteButton的可见性,来判断Available Cast Devices

    public static boolean checkCastDevice(Context activity) {
        //如果当前无连接, 说明unavailable Cast devices
        if (!NetworkMonitor.isConnected(App.applicationContext())) return false;
        MediaRouter mediaRouter = MediaRouter.getInstance(activity);
        List<MediaRouter.RouteInfo> routes = mediaRouter.getRoutes();
        if (routes != null && routes.size() != 0) {
            for (MediaRouter.RouteInfo info : routes) {
                if (info.getDeviceType() != MediaRouter.RouteInfo.CONNECTION_STATE_DISCONNECTED
                        && !info.isDefault() && !info.isBluetooth() && !info.isDeviceSpeaker()) {
                    return true;
                }
            }
        }
        return false;
    }
    private NetworkMonitor.OnNetworkListener onNetWorkListener = (last, current) -> {
        showMediaRouteButton(CastHelper.checkCastDevice(getActivity()));
        //check MediaRouteButton isVisible
        ...
    };

总结

部分设备当非杀进程重新启动App,不能主动扫描routes, 需要在添加主动扫描,来获取最新的Cast Devices

部分设备无法获取onCastStateChanged回调,且MediaRouteButton内部会监听连接状态设置显隐性, 所以我们也同样监听连接状态的变化,来判断Cast 是否可用

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