本頁面由 Cloud Translation API 翻譯而成。

使用 Wi-Fi Direct 建立 P2P 連線

Wi-Fi Direct (也稱為點對點或 P2P) 可讓應用程式快速尋找鄰近裝置並進行互動裝置的藍牙功能

Wi-Fi Direct (P2P) API 可讓應用程式在沒有 Wi-Fi Direct (P2P) API 的情況下與附近的裝置連線。需要連線至網路或無線基地台。如果您的應用程式是專為安全、鄰近範圍的網路或 Wi-Fi 設計比起傳統 Wi-Fi 臨時檔案，直接流量是更合適的選項網路的原因如下：

Wi-Fi Direct 支援 WPA2 加密。(部分臨時聯播網僅支援 WEP 加密)。
裝置可以廣播自身提供的服務，讓裝置更容易找出合適的同類應用程式
決定哪部裝置應為網路的群組擁有者時 Wi-Fi Direct 會檢查每部裝置的電源管理、UI 和服務並根據這些資訊選擇可處理資料的裝置最有效率
Android 不支援 Wi-Fi 臨時模式。

本課程將說明如何使用 Wi-Fi P2P 尋找鄰近裝置並連線。

設定應用程式權限

如要使用 Wi-Fi Direct，請在 ACCESS_FINE_LOCATION, CHANGE_WIFI_STATE, ACCESS_WIFI_STATE和 INTERNET 權限的權限。如果應用程式指定 Android 13 (API 級別 33) 以上版本，請一併新增 NEARBY_WIFI_DEVICES 授予資訊清單的權限。Wi-Fi 直接連結不需要網際網路連線，但採用標準 Java 通訊端，需要 INTERNET 權限。因此，您必須具備下列權限，才能使用 Wi-Fi Direct：

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.android.nsdchat"
    ...
    <!-- If your app targets Android 13 (API level 33)
         or higher, you must declare the NEARBY_WIFI_DEVICES permission. -->
        <uses-permission android:name="android.permission.NEARBY_WIFI_DEVICES"
        <!-- If your app derives location information from Wi-Fi APIs,
             don't include the "usesPermissionFlags" attribute. -->
        android:usesPermissionFlags="neverForLocation" />
        
    <uses-permission
        android:required="true"
        android:name="android.permission.ACCESS_FINE_LOCATION"
        <!-- If any feature in your app relies on precise location information,
             don't include the "maxSdkVersion" attribute. -->
        android:maxSdkVersion="32" />
    <uses-permission
        android:required="true"
        android:name="android.permission.ACCESS_WIFI_STATE"/>
    <uses-permission
        android:required="true"
        android:name="android.permission.CHANGE_WIFI_STATE"/>
    <uses-permission
        android:required="true"
        android:name="android.permission.INTERNET"/>
    ...

除了上述權限，下列 API 也需啟用定位模式：

設定廣播接收器和點對點管理員

如要使用 Wi-Fi Direct，您必須監聽廣播意圖，透過語音告知來回應應用程式在您的應用程式中，將執行個體化 IntentFilter，並將其設定為監聽下列內容：

WIFI_P2P_STATE_CHANGED_ACTION: 指出 Wi-Fi Direct 是否已啟用
WIFI_P2P_PEERS_CHANGED_ACTION: 表示可用的同類群組清單有所變更。
WIFI_P2P_CONNECTION_CHANGED_ACTION: 指出 Wi-Fi Direct 連線狀態已變更。開頭是 Android 10 版本則非固定式。如果您的應用程式仰賴這些於註冊時播送get 方法才能取得資訊。
WIFI_P2P_THIS_DEVICE_CHANGED_ACTION: 表示這部裝置的設定詳細資料已變更。開頭是 Android 10 版本則非固定式。如果您的應用程式仰賴這些於註冊時播送get 方法才能取得資訊。

Kotlin

private val intentFilter = IntentFilter()
...
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.main)

    // Indicates a change in the Wi-Fi Direct status.
    intentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION)

    // Indicates a change in the list of available peers.
    intentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION)

    // Indicates the state of Wi-Fi Direct connectivity has changed.
    intentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION)

    // Indicates this device's details have changed.
    intentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION)
    ...
}

Java

private final IntentFilter intentFilter = new IntentFilter();
...
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    // Indicates a change in the Wi-Fi Direct status.
    intentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);

    // Indicates a change in the list of available peers.
    intentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);

    // Indicates the state of Wi-Fi Direct connectivity has changed.
    intentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);

    // Indicates this device's details have changed.
    intentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
    ...
}

在 onCreate() 方法的結尾，取得 WifiP2pManager 的例項，並呼叫其 initialize() 方法。這個方法會傳回 WifiP2pManager.Channel 物件，稍後您將用到該物件將應用程式連上 Wi-Fi Direct 架構。

Kotlin

private lateinit var channel: WifiP2pManager.Channel
private lateinit var manager: WifiP2pManager

override fun onCreate(savedInstanceState: Bundle?) {
    ...
    manager = getSystemService(Context.WIFI_P2P_SERVICE) as WifiP2pManager
    channel = manager.initialize(this, mainLooper, null)
}

Java

Channel channel;
WifiP2pManager manager;

@Override
public void onCreate(Bundle savedInstanceState) {
    ...
    manager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE);
    channel = manager.initialize(this, getMainLooper(), null);
}

現在請建立新的 BroadcastReceiver 類別，以便監聽變更切換系統的 Wi-Fi 狀態在「onReceive()」中方法，請新增條件來處理上述各項狀態變更。

Kotlin

override fun onReceive(context: Context, intent: Intent) {
    when(intent.action) {
        WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION -> {
            // Determine if Wi-Fi Direct mode is enabled or not, alert
            // the Activity.
            val state = intent.getIntExtra(WifiP2pManager.EXTRA_WIFI_STATE, -1)
            activity.isWifiP2pEnabled = state == WifiP2pManager.WIFI_P2P_STATE_ENABLED
        }
        WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION -> {

            // The peer list has changed! We should probably do something about
            // that.

        }
        WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION -> {

            // Connection state changed! We should probably do something about
            // that.

        }
        WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION -> {
            (activity.supportFragmentManager.findFragmentById(R.id.frag_list) as DeviceListFragment)
                    .apply {
                        updateThisDevice(
                                intent.getParcelableExtra(
                                        WifiP2pManager.EXTRA_WIFI_P2P_DEVICE) as WifiP2pDevice
                        )
                    }
        }
    }
}

Java

@Override
public void onReceive(Context context, Intent intent) {
    String action = intent.getAction();
    if (WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION.equals(action)) {
        // Determine if Wi-Fi Direct mode is enabled or not, alert
        // the Activity.
        int state = intent.getIntExtra(WifiP2pManager.EXTRA_WIFI_STATE, -1);
        if (state == WifiP2pManager.WIFI_P2P_STATE_ENABLED) {
            activity.setIsWifiP2pEnabled(true);
        } else {
            activity.setIsWifiP2pEnabled(false);
        }
    } else if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) {

        // The peer list has changed! We should probably do something about
        // that.

    } else if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {

        // Connection state changed! We should probably do something about
        // that.

    } else if (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action)) {
        DeviceListFragment fragment = (DeviceListFragment) activity.getFragmentManager()
                .findFragmentById(R.id.frag_list);
        fragment.updateThisDevice((WifiP2pDevice) intent.getParcelableExtra(
                WifiP2pManager.EXTRA_WIFI_P2P_DEVICE));

    }
}

最後，請新增程式碼，註冊意圖篩選器和廣播接收器主要活動，並在活動暫停時取消註冊。最好是在 onResume() 和 onPause() 方法。

Kotlin

/** register the BroadcastReceiver with the intent values to be matched  */
public override fun onResume() {
    super.onResume()
    receiver = WiFiDirectBroadcastReceiver(manager, channel, this)
    registerReceiver(receiver, intentFilter)
}

public override fun onPause() {
    super.onPause()
    unregisterReceiver(receiver)
}

Java

/** register the BroadcastReceiver with the intent values to be matched */
@Override
public void onResume() {
    super.onResume();
    receiver = new WiFiDirectBroadcastReceiver(manager, channel, this);
    registerReceiver(receiver, intentFilter);
}

@Override
public void onPause() {
    super.onPause();
    unregisterReceiver(receiver);
}

啟動同業探索功能

如要開始透過 Wi-Fi P2P 搜尋鄰近裝置，請呼叫 discoverPeers()。這個方法會使用

你獲得的WifiP2pManager.Channel 您初始化點對點 mManager 後收到的回覆
使用方法實作 WifiP2pManager.ActionListener 系統會叫用以獲得成功和失敗的曝光機會

Kotlin

manager.discoverPeers(channel, object : WifiP2pManager.ActionListener {

    override fun onSuccess() {
        // Code for when the discovery initiation is successful goes here.
        // No services have actually been discovered yet, so this method
        // can often be left blank. Code for peer discovery goes in the
        // onReceive method, detailed below.
    }

    override fun onFailure(reasonCode: Int) {
        // Code for when the discovery initiation fails goes here.
        // Alert the user that something went wrong.
    }
})

Java

manager.discoverPeers(channel, new WifiP2pManager.ActionListener() {

    @Override
    public void onSuccess() {
        // Code for when the discovery initiation is successful goes here.
        // No services have actually been discovered yet, so this method
        // can often be left blank. Code for peer discovery goes in the
        // onReceive method, detailed below.
    }

    @Override
    public void onFailure(int reasonCode) {
        // Code for when the discovery initiation fails goes here.
        // Alert the user that something went wrong.
    }
});

請注意，這項操作只會「啟動」同業探索功能。 discoverPeers() 方法會啟動探索程序，然後會立即傳回值系統會在以下情況下，通知您對等互連探索程序：透過在提供的動作事件監聽器中呼叫方法，成功啟動該事件。此外，探索功能仍然有效，直到啟動連線或 P2P 群組為止

擷取同類應用程式清單

現在請編寫用於擷取及處理同業清單的程式碼。頭等艙實作 WifiP2pManager.PeerListListener 介面，提供 Wi-Fi Direct 的對等連線相關資訊。應用程式也可利用這項資訊，判斷同類應用程式何時加入或離開網路下列程式碼片段說明這些作業與同類應用程式有關：

Kotlin

private val peers = mutableListOf<WifiP2pDevice>()
...

private val peerListListener = WifiP2pManager.PeerListListener { peerList ->
    val refreshedPeers = peerList.deviceList
    if (refreshedPeers != peers) {
        peers.clear()
        peers.addAll(refreshedPeers)

        // If an AdapterView is backed by this data, notify it
        // of the change. For instance, if you have a ListView of
        // available peers, trigger an update.
        (listAdapter as WiFiPeerListAdapter).notifyDataSetChanged()

        // Perform any other updates needed based on the new list of
        // peers connected to the Wi-Fi P2P network.
    }

    if (peers.isEmpty()) {
        Log.d(TAG, "No devices found")
        return@PeerListListener
    }
}

Java

private List<WifiP2pDevice> peers = new ArrayList<WifiP2pDevice>();
...

private PeerListListener peerListListener = new PeerListListener() {
    @Override
    public void onPeersAvailable(WifiP2pDeviceList peerList) {

        List<WifiP2pDevice> refreshedPeers = peerList.getDeviceList();
        if (!refreshedPeers.equals(peers)) {
            peers.clear();
            peers.addAll(refreshedPeers);

            // If an AdapterView is backed by this data, notify it
            // of the change. For instance, if you have a ListView of
            // available peers, trigger an update.
            ((WiFiPeerListAdapter) getListAdapter()).notifyDataSetChanged();

            // Perform any other updates needed based on the new list of
            // peers connected to the Wi-Fi P2P network.
        }

        if (peers.size() == 0) {
            Log.d(WiFiDirectActivity.TAG, "No devices found");
            return;
        }
    }
}

現在修改廣播接收器的 onReceive() 接收含有 WIFI_P2P_PEERS_CHANGED_ACTION 動作的意圖時，呼叫 requestPeers() 的方法。個人中心就需要將此事件監聽器傳遞至接收器其中一個方法是直接傳送做為廣播接收器建構函式的引數。

Kotlin

fun onReceive(context: Context, intent: Intent) {
    when (intent.action) {
        ...
        WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION -> {

            // Request available peers from the wifi p2p manager. This is an
            // asynchronous call and the calling activity is notified with a
            // callback on PeerListListener.onPeersAvailable()
            mManager?.requestPeers(channel, peerListListener)
            Log.d(TAG, "P2P peers changed")


        }
        ...
    }
}

Java

public void onReceive(Context context, Intent intent) {
    ...
    else if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) {

        // Request available peers from the wifi p2p manager. This is an
        // asynchronous call and the calling activity is notified with a
        // callback on PeerListListener.onPeersAvailable()
        if (mManager != null) {
            mManager.requestPeers(channel, peerListListener);
        }
        Log.d(WiFiDirectActivity.TAG, "P2P peers changed");
    }...
}

現在，意圖包含動作 WIFI_P2P_PEERS_CHANGED_ACTION 的意圖觸發更新同類群組清單的要求。

與同業交流

如要連線至對等點，請建立新的 WifiP2pConfig 物件，並將資料從 WifiP2pDevice 代表您想要的裝置物件。然後呼叫 connect() 方法。

Kotlin

override fun connect() {
    // Picking the first device found on the network.
    val device = peers[0]

    val config = WifiP2pConfig().apply {
        deviceAddress = device.deviceAddress
        wps.setup = WpsInfo.PBC
    }

    manager.connect(channel, config, object : WifiP2pManager.ActionListener {

        override fun onSuccess() {
            // WiFiDirectBroadcastReceiver notifies us. Ignore for now.
        }

        override fun onFailure(reason: Int) {
            Toast.makeText(
                    this@WiFiDirectActivity,
                    "Connect failed. Retry.",
                    Toast.LENGTH_SHORT
            ).show()
        }
    })
}

Java

@Override
public void connect() {
    // Picking the first device found on the network.
    WifiP2pDevice device = peers.get(0);

    WifiP2pConfig config = new WifiP2pConfig();
    config.deviceAddress = device.deviceAddress;
    config.wps.setup = WpsInfo.PBC;

    manager.connect(channel, config, new ActionListener() {

        @Override
        public void onSuccess() {
            // WiFiDirectBroadcastReceiver notifies us. Ignore for now.
        }

        @Override
        public void onFailure(int reason) {
            Toast.makeText(WiFiDirectActivity.this, "Connect failed. Retry.",
                    Toast.LENGTH_SHORT).show();
        }
    });
}

如果群組中的每部裝置都支援 Wi-Fi Direct，您就不需要，在連線時明確要求群組的密碼。如何允許裝置但不支援 Wi-Fi Direct 加入群組，但是您需要請呼叫 requestGroupInfo()，如如以下程式碼片段所示：

Kotlin

manager.requestGroupInfo(channel) { group ->
    val groupPassword = group.passphrase
}

Java

manager.requestGroupInfo(channel, new GroupInfoListener() {
  @Override
  public void onGroupInfoAvailable(WifiP2pGroup group) {
      String groupPassword = group.getPassphrase();
  }
});

請注意，WifiP2pManager.ActionListener connect() 方法只會在啟動時通知您無論成功還是失敗如要監聽連線狀態的變更，請實作 WifiP2pManager.ConnectionInfoListener 介面。且 onConnectionInfoAvailable() 回呼會在連線變更。需要同時連上多部裝置時在單一裝置上 (例如有三名以上玩家的遊戲或即時通訊應用程式) 時，一部裝置就大功告成即為「群組擁有者」您可以指定將特定裝置確認網路的群組擁有者「建立群組」部分。

Kotlin

private val connectionListener = WifiP2pManager.ConnectionInfoListener { info ->

    // String from WifiP2pInfo struct
    val groupOwnerAddress: String = info.groupOwnerAddress.hostAddress

    // After the group negotiation, we can determine the group owner
    // (server).
    if (info.groupFormed && info.isGroupOwner) {
        // Do whatever tasks are specific to the group owner.
        // One common case is creating a group owner thread and accepting
        // incoming connections.
    } else if (info.groupFormed) {
        // The other device acts as the peer (client). In this case,
        // you'll want to create a peer thread that connects
        // to the group owner.
    }
}

Java

@Override
public void onConnectionInfoAvailable(final WifiP2pInfo info) {

    // String from WifiP2pInfo struct
    String groupOwnerAddress = info.groupOwnerAddress.getHostAddress();

    // After the group negotiation, we can determine the group owner
    // (server).
    if (info.groupFormed && info.isGroupOwner) {
        // Do whatever tasks are specific to the group owner.
        // One common case is creating a group owner thread and accepting
        // incoming connections.
    } else if (info.groupFormed) {
        // The other device acts as the peer (client). In this case,
        // you'll want to create a peer thread that connects
        // to the group owner.
    }
}

現在，返回廣播接收器的 onReceive() 方法，然後修改區段監聽 WIFI_P2P_CONNECTION_CHANGED_ACTION 意圖收到這項意圖時，請呼叫 requestConnectionInfo()。這是非同步呼叫因此，結果會由您提供的連線資訊事件監聽器接收參數。

Kotlin

when (intent.action) {
    ...
    WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION -> {

        // Connection state changed! We should probably do something about
        // that.

        mManager?.let { manager ->

            val networkInfo: NetworkInfo? = intent
                    .getParcelableExtra(WifiP2pManager.EXTRA_NETWORK_INFO) as NetworkInfo

            if (networkInfo?.isConnected == true) {

                // We are connected with the other device, request connection
                // info to find group owner IP

                manager.requestConnectionInfo(channel, connectionListener)
            }
        }
    }
    ...
}

Java

    ...
    } else if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {

        if (manager == null) {
            return;
        }

        NetworkInfo networkInfo = (NetworkInfo) intent
                .getParcelableExtra(WifiP2pManager.EXTRA_NETWORK_INFO);

        if (networkInfo.isConnected()) {

            // We are connected with the other device, request connection
            // info to find group owner IP

            manager.requestConnectionInfo(channel, connectionListener);
        }
        ...

建立群組

如果您希望執行應用程式的裝置擔任以下應用程式的群組擁有者：支援網路，也就是不支援 Wi-Fi Direct 功能，請按照連結至同類應用程式部分，除非您建立新的 WifiP2pManager.ActionListener 使用 createGroup()，而不是 connect()。在 WifiP2pManager.ActionListener 相同，如以下程式碼片段所示：

Kotlin

manager.createGroup(channel, object : WifiP2pManager.ActionListener {
    override fun onSuccess() {
        // Device is ready to accept incoming connections from peers.
    }

    override fun onFailure(reason: Int) {
        Toast.makeText(
                this@WiFiDirectActivity,
                "P2P group creation failed. Retry.",
                Toast.LENGTH_SHORT
        ).show()
    }
})

Java

manager.createGroup(channel, new WifiP2pManager.ActionListener() {
    @Override
    public void onSuccess() {
        // Device is ready to accept incoming connections from peers.
    }

    @Override
    public void onFailure(int reason) {
        Toast.makeText(WiFiDirectActivity.this, "P2P group creation failed. Retry.",
                Toast.LENGTH_SHORT).show();
    }
});

注意： 如果網路中的所有裝置都支援 Wi-Fi 您可以直接在裝置上使用 connect() 方法，因為方法建立群組並自動選取版主。

建立群組後，你可以撥打 requestGroupInfo()：擷取以下資料夾中的對等項目詳細資料：包括裝置名稱和連線狀態