title: Android WiFi Display
tag: Android
category: Android
date: 2019-12-01
文章目录
- Android WiFi Display (Miracast)
- 技术体系:
- 流媒体协议
- P2P使用demo
- client端
- Server端
- 参考
- 问题记录
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
- 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
- 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:$reason")
}
})
- 广播接收:
- 保证P2P打开:
WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION -> {
when (intent.getIntExtra(WifiP2pManager.EXTRA_WIFI_STATE, -1)) {
WifiP2pManager.WIFI_P2P_STATE_ENABLED -> {
// Wifi P2P is enabled
Log.d(localClassName, "P2P is enabled")
}
else -> {
// Wi-Fi P2P is not enabled
Log.d(localClassName, "P2P is not enabled")
}
}
}
- 得到附近所有的支持P2P的设备peers:
WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION -> {
Log.d(localClassName, "可用的peer list发生改变")
mWifiP2pManager?.requestPeers(mChannel) { peers -> availablePeers(peers) }
}
private fun availablePeers(peers: WifiP2pDeviceList?) {
Log.d(localClassName, "size:${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()
}
- 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")
}
})
- 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")
}
}
}
}
}
- 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)
}
}
}
- 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")
}
})
Server端
- 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
- 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: $reason")
}
})
Server可以不用去扫描设备,只需要在P2P中注册就可以了,等待被发现
- 创建ServerSocket,监听:
inner class ListenThread : Thread() {
private val mServerSocket: ServerSocket = ServerSocket(WIFI_P2P_PORT)
override fun run() {
while (true) {
Log.d(javaClass.name, "server socket bg")
val client = mServerSocket.accept()
mHandler?.takeIf { mFilePath != null }?.apply {
ServerAsyncTask(this, mFilePath!!).execute(client)
}
}
}
}
在子线程不断监听某个端口,等待连接就可以了
- accept成功,通信:
val client = params[0]
return client?.use { socket ->
val f = File(mFilePath, "wifip2pshared-${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
- 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 - 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) - 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??