title: Android WiFi Display
tag: Android
category: Android
date: 2019-12-01
Android WiFi Display (Miracast)
投屏技术协议:
DLNA:Digital Living Network Alliance,PC、移动设备、消费电器之间互联互通的协议
AirPlay:苹果开发的无线技术,通过WiFi传输,支持DLNA没有的镜像(设备显示什么,显示屏幕也显示什么)
Miracast:以WiFi Direct为基础的无线显示标准
DLNA
蓝牙:蓝牙发现
WiFi Direct:WiFi直连
Nsd:网络服务发现
技术体系:
- WiFi Direct:WiFi P2P,支持在没有AP(Access Point)下,WiFi设备直连并通信
- WiFi Protected Setup:用于用户自动配置WiFi网络、添加WiFi设备
- 11n/WMM/WPA2:11n是802.11n协议(56M提升至600M);WMM是WiFi Multimedia,针对实时视音频数据的QoS服务;WPA2是WiFi Protected Acess2,传输加密保护
- WiFi Display相关Service:
MediaPlayerService及相关模块:RTP/RTSP及相应的编解码技术
SurfaceFlinger及相关模块:SurfaceFlinger是将各层UI数据混屏并投递到显示设备中去显示
WindowManagerService及相关模块:用于管理系统中各个UI层的位置和属性
DisplayManagerService:用于管理系统显示设备的生命周期,包括物理屏幕、虚拟屏幕、WiFi Display
WifiService及相关模块:WifiDisplay建立在P2P基础上
MediaRouterService:管理各个应用程序的多媒体播放的行为
MediaRouter:用于和MediaRouterService交互一起管理多媒体的播放行为,并维护当前已经配对上的remote display设备,包括WiFi Display、蓝牙A2DP、chromecast设备
WifiDisplayAdapter:用于DisplayManagerService管理WiFi Display显示的Adapter
WifiDisplayController:用于控制扫描wifi display设备、连接、断开等操作
Android中关注:WiFi Direct(WifiP2pService管理和控制),WiFi Multimedia
Miracast工作流程:
SurfaceFlinger对Miracast的支持
Wifi P2P:Android wifi探究三:Wifi P2P 连接附近设备
流媒体协议
- RTP:Real-time Transport Protocol,传送具有实时属性的数据,建立在UDP上,不保证传送或防止无序传送,允许接收方重组发送方的包序列(例子:视频解码,就不需要顺序解码)
- RTCP:Real-time Transport Control Protocol,RTP的控制协议,监控服务质量并传送正在进行的会话参与者的相关信息;为RTP媒体流提供信道外控制
- SRTCP:Secure Real-time Transport Protocol,在RTP基础上定义的一个协议,用于为单播和多播应用程序中的实时传输协议的数据提供加密、消息认证、完整性保护和重放保护
- RTSP:Real-time Streaming Protocol,控制声音或影像的多媒体串流协议,并允许同时多个串流需求控制; 该协议目的在于控制多个数据发送连接,为选择发送通道,如UDP、多播UDP与TCP提供途径,并为选择基于RTP上发送机制提供方法 ;RTSP是双向实时数据传输协议,允许客户端向服务端发送请求(如回放、快进、倒退等);(算是在应用层协议????)
- SDP:会话描述协议
RTSP发起/终结流媒体、RTP传输流媒体数据 、RTCP对RTP进行控制,同步
P2P使用demo
client端
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权限申请和检查:
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <!--Wifi P2P 权限一定要有,不然获取不到--> <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" /> <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" /> <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" /> <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> <uses-permission android:name="android.permission.READ_PHONE_STATE" /> <uses-feature android:name="android.hardware.wifi.direct" android:required="true"/>
部分权限根据API需要动态申请,如WiFi的状态和打开、位置信息的获取
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初始化P2P设备,注册广播监听器:
val intentFilter = IntentFilter().apply { addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION) addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION) addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION) addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION) } registerReceiver(mReceiver, intentFilter) mWifiP2pManager = getSystemService(Context.WIFI_P2P_SERVICE) as WifiP2pManager // 用这个通道来查找和连接P2P设备 在 WLAN P2P 框架中注册您的应用 mChannel = mWifiP2pManager?.initialize(this, mainLooper) { Log.d(localClassName, "channel disconnected") } // 查找附近P2P设备 mWifiP2pManager?.discoverPeers(mChannel, object : WifiP2pManager.ActionListener { override fun onSuccess() { Log.d(localClassName, "discoverPeers onSuccess") } override fun onFailure(reason: Int) { Log.w(localClassName, "discoverPeers onFailure:$reason") } })
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广播接收:
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保证P2P打开:
WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION -> { when (intent.getIntExtra(WifiP2pManager.EXTRA_WIFI_STATE, -1)) { WifiP2pManager.WIFI_P2P_STATE_ENABLED -> { // Wifi P2P is enabled Log.d(localClassName, "P2P is enabled") } else -> { // Wi-Fi P2P is not enabled Log.d(localClassName, "P2P is not enabled") } } }
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得到附近所有的支持P2P的设备peers:
WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION -> { Log.d(localClassName, "可用的peer list发生改变") mWifiP2pManager?.requestPeers(mChannel) { peers -> availablePeers(peers) } } private fun availablePeers(peers: WifiP2pDeviceList?) { Log.d(localClassName, "size:${peers?.deviceList?.size}") mAdapter.clear() peers?.deviceList?.forEach { wifiP2pDevice -> val name = wifiP2pDevice.deviceName val address = wifiP2pDevice.deviceAddress val status = when(wifiP2pDevice.status) { WifiP2pDevice.CONNECTED -> "connected" WifiP2pDevice.INVITED -> "invited" WifiP2pDevice.FAILED -> "failed" WifiP2pDevice.AVAILABLE -> "available" WifiP2pDevice.UNAVAILABLE -> "unavailable" else -> "unknown" } mAdapter.add("$name : $status\n$address") } mAdapter.notifyDataSetChanged() }
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选择连接:
val str = mAdapter.getItem(position) val strs = str?.split('\n') val address = strs?.get(1) Log.d(localClassName, "item click: $str address: $address") // val wifiP2pDevice = mPeers?.get(address) val config = WifiP2pConfig() config.deviceAddress = address config.wps.setup = WpsInfo.PBC mWifiP2pManager?.connect(mChannel, config, object : WifiP2pManager.ActionListener { override fun onSuccess() { Log.d(localClassName, "connect onSuccess") } override fun onFailure(reason: Int) { Log.w(localClassName, "connect onFailure:$reason") } })
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连接成功后,获取连接的WifiP2pInfo:
WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION -> { Log.d(localClassName, "P2P连接状态发生改变") // 可以直接通过intent拿到WifiP2pGroup WifiP2pInfo // val group = intent.getParcelableExtra<WifiP2pGroup>(WifiP2pManager.EXTRA_WIFI_P2P_GROUP) // 也可以通过request去获取 // mWifiP2pManager.requestNetworkInfo(mChannel) { networkInfo -> // Log.d(localClassName, "networkInfo:$networkInfo") // } val networkInfo = intent.getParcelableExtra<NetworkInfo>(WifiP2pManager.EXTRA_NETWORK_INFO) networkInfo?.takeIf { it.isConnected }?.let { mWifiP2pManager?.requestGroupInfo(mChannel) { wifiP2pGroup -> val wifiP2pDevices = wifiP2pGroup.clientList val wifiP2p2DeviceOwner = wifiP2pGroup.owner Log.d(localClassName, "group p2pInfo:$wifiP2pGroup") tv_client_connected.post { tv_client_connected.text = wifiP2pGroup.networkName } } mWifiP2pManager?.requestConnectionInfo(mChannel) { wifiP2pInfo: WifiP2pInfo? -> mWifiP2pInfo = wifiP2pInfo Log.d(localClassName, "wifi p2pInfo $mWifiP2pInfo") mWifiP2pInfo?.let { if (it.groupFormed && it.isGroupOwner) { Toast.makeText(this@WifiP2PClientActivity, "can be connected", Toast.LENGTH_SHORT).show() } else if (it.groupFormed) { Log.d(localClassName, "The other device acts as the client. In this case, we enable the get file button") } } } } }
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获取IP,创建Socket进行连接Server端:
val fileUri = extras?.getString(EXTRAS_FILE_PATH) val host = extras?.getString(EXTRAS_GROUP_OWNER_ADDRESS) val port = extras?.getInt(EXTRAS_GROUP_OWNER_PORT) if (fileUri == null || host == null || port == null) { Log.e(javaClass.name, "fileUri: $fileUri, host: $host, port: $port") return } val socket = Socket() try { Log.d(javaClass.name, "opening client socket") socket.bind(null) socket.connect(InetSocketAddress(host, port), SOCKET_TIME_OUT) Log.d(javaClass.name, "client socket:${socket.isConnected}") val outputStream = socket.getOutputStream() val contentResolver = applicationContext.contentResolver var inputStream: InputStream? = null try { inputStream = contentResolver.openInputStream(Uri.parse(fileUri)) } catch (e: FileNotFoundException) { Log.e(javaClass.name, "file not found exception", e) } inputStream?.let { StreamUtil.copyFile(it,outputStream) } Log.d(javaClass.name, "Client data written") } catch (e: IOException) { Log.e(javaClass.name, "client socket error", e) } finally { socket.takeIf { it.isConnected }?.apply { try { close() } catch (e: IOException) { Log.e(javaClass.name, "client socket close error", e) } } }
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断开连接:
mWifiP2pManager?.removeGroup(mChannel, object : WifiP2pManager.ActionListener { override fun onSuccess() { Log.d(localClassName, "disconnect success") } override fun onFailure(reason: Int) { Log.w(localClassName, "disconnect failed:$reason") } })
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Server端
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权限申请:
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" /> <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" /> <!--Wifi P2P 权限一定要有,不然获取不到--> <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" /> <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" /> <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" /> <uses-permission android:name="android.permission.INTERNET" /> <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" /> <uses-permission android:name="android.permission.READ_PHONE_STATE" /> <uses-feature android:name="android.hardware.wifi.direct" android:required="true"/>
同样部分权限需要主动申请
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初始化P2P:
val intentFilter = IntentFilter().apply { addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION) addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION) addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION) addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION) } registerReceiver(mReceiver, intentFilter) mWifiP2pManager = getSystemService(Context.WIFI_P2P_SERVICE) as WifiP2pManager // 用这个通道来查找和连接P2P设备 在 WLAN P2P 框架中注册您的应用 mChannel = mWifiP2pManager?.initialize(this, mainLooper) { Log.d(localClassName, "channel disconnected") } mWifiP2pManager?.discoverPeers(mChannel, object : WifiP2pManager.ActionListener { override fun onSuccess() { Log.d(localClassName, "discover success") } override fun onFailure(reason: Int) { Log.w(localClassName, "discover failed") } }) // 用于创建GroupOwner,决定谁是Group的主导者 mWifiP2pManager?.createGroup(mChannel, object : WifiP2pManager.ActionListener { override fun onSuccess() { Log.d(localClassName, "createGroup success") } override fun onFailure(reason: Int) { Log.w(localClassName, "create group failed: $reason") } })
Server可以不用去扫描设备,只需要在P2P中注册就可以了,等待被发现
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创建ServerSocket,监听:
inner class ListenThread : Thread() { private val mServerSocket: ServerSocket = ServerSocket(WIFI_P2P_PORT) override fun run() { while (true) { Log.d(javaClass.name, "server socket bg") val client = mServerSocket.accept() mHandler?.takeIf { mFilePath != null }?.apply { ServerAsyncTask(this, mFilePath!!).execute(client) } } } }
在子线程不断监听某个端口,等待连接就可以了
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accept成功,通信:
val client = params[0] return client?.use { socket -> val f = File(mFilePath, "wifip2pshared-${System.currentTimeMillis()}.jpg") val dirs = File(f.parent?:mFilePath) dirs.takeIf { !it.exists() }?.apply { mkdirs() } f.createNewFile() val inputStream = socket.getInputStream() StreamUtil.copyFile(inputStream, FileOutputStream(f)) socket.close() f.absolutePath }
参考
Android Wi-Fi Display(Miracast)介绍
多屏互动技术研究(二)之WifiDisplay(Miracast)技术原理及实现
问题记录
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socket连接失败:
原因:由于server端对客户端的监听只是用了一个AyncTask,所以导致一次socket通信完成后,后续的再无法进行通信
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设备一会查找得到,一会查找不到:
原因:server端没有去初始化P2P,也就没有在WiFi P2P框架中去注册,导致无法client端就无法发现设备,同时server端也要启动discoverPeers,这样才能确保能够被发现,并且GroupOwner也是Server端所持有(并不绝对,可以通过createGroup来决定,最好是在Server端)
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在UI线程更新UI导致的NetworkOnMainThreadException:
原因:
mWifiP2pInfo?.groupOwnerAddress?.hostAddress
,直接通过WiFiP2PInfo去获取了GroupOwnerAddress,然后去获取HostAddress,这个调用过程产生了网络请求??