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 && 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
- 问题1，方法1 只有在进程销毁后第一次启动可以获取周围Available Cast Devices，之后关闭APP重启一直返回false
- 问题2，方法2 APP处于前台时，断开WIFI时，Cast Button消失，重新连接WIFI，Cast Button可见，但代码中并没有收到Cast Devices 状态更新的回调， 设置Cast Button Visibility的代码并未执行，这就出现一种情况：虽然Cast Button不可见，但是新增的视图却并未显示。
分析
- 问题1
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。
- 问题2
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);
}
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
- 当前连接断开， 直接隐藏MediaRouteButton
- 当前连接恢复， 查询是否有Available Cast Devices，来设置MediaRouteButton可见
- 再判断MediaRouteButton是否可见，来设置新视图的可见性
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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