android wifi直连 wifip2pmanager

android wifi直连 wifip2pmanager；使用WiFi 直连，然后通过udp进行通讯。
Android WiFi 直连（Wi-Fi Direct，也称为Wi-Fi P2P）是一种让两台或多台设备通过Wi-Fi技术直接进行点对点连接的技术，无需借助传统的无线路由器或接入点。这种技术使得设备间可以快速建立安全的无线连接，实现文件传输、屏幕共享、游戏对战等多种应用，尤其适用于智能手机、平板电脑、打印机、相机等消费电子设备间的近距离通信。

以下是Android WiFi 直连的基本工作原理和使用步骤：

工作原理：
设备发现：启用Wi-Fi Direct功能的设备可以通过广播信号搜索和发现附近的其他支持Wi-Fi Direct的设备。设备间可以互相检测到对方的存在，并显示在设备列表中供用户选择。

连接请求：用户在设备列表中选择要连接的目标设备后，发起连接请求。目标设备收到请求后，通常需要手动或自动确认接受连接。

组建立：一旦连接请求被接受，两台设备之间会自动建立一个Wi-Fi Direct组。在这个组中，一台设备会被选为“组主人”（Group Owner，GO），相当于小型网络的接入点，负责管理组内的连接和数据传输。另一台设备则作为“客户端”（Client）加入该组。

数据传输：连接建立后，组主人和客户端设备可以使用各自的IP地址和端口号进行直接的TCP/UDP通信。应用程序可以利用这些网络参数创建Socket连接，进行文件传输、消息传递等操作。

例子代码：

public class WifiConnectActivity extends AppCompatActivity {private Button btnConnect;private WifiDirectLink wifiDirectLink;@Overrideprotected void onCreate(@Nullable Bundle savedInstanceState) {super.onCreate(savedInstanceState);LinearLayout linearLayout = new LinearLayout(this);linearLayout.setOrientation(LinearLayout.VERTICAL);setContentView(linearLayout);btnConnect = new AppCompatButton(this);btnConnect.setText("链接");AppCompatButton btnConnect2 = new AppCompatButton(this);btnConnect2.setText("发送");linearLayout.addView(btnConnect);linearLayout.addView(btnConnect2);wifiDirectLink = new WifiDirectLink(getApplicationContext());// 按钮点击事件 - 连接到对等设备btnConnect.setOnClickListener(v -> wifiDirectLink.connectToPeer());btnConnect2.setOnClickListener(v -> wifiDirectLink.send("hello".getBytes()));if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION, Manifest.permission.NEARBY_WIFI_DEVICES}, 119);} else {ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 119);}}@Overrideprotected void onDestroy() {wifiDirectLink.release();super.onDestroy();}}

连接工具类：

import android.annotation.SuppressLint;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.wifi.p2p.WifiP2pConfig;
import android.net.wifi.p2p.WifiP2pDevice;
import android.net.wifi.p2p.WifiP2pDeviceList;
import android.net.wifi.p2p.WifiP2pInfo;
import android.net.wifi.p2p.WifiP2pManager;
import android.os.Build;
import android.os.Handler;
import android.os.Looper;
import android.text.TextUtils;
import android.util.Log;
import android.widget.Toast;import androidx.core.content.ContextCompat;import java.net.InetAddress;
import java.util.ArrayList;
import java.util.List;public class WifiDirectLink {private static final String TAG = "WifiDirectLink";private final WifiP2pManager wifiP2pManager;private final WifiP2pManager.Channel channel;private Context context;private final Handler handler = new Handler(Looper.getMainLooper());private SyncUDP udp;private String otherClientIp;public WifiDirectLink(Context context) {this.context = context;Log.i(TAG, "WifiDirectLink: begin start-----------------------------------------------");if (udp == null) {udp = new SyncUDP(Config.BROADCAST_PORT + 3);udp.setListener(this::receiveAction);}// 初始化Wi-Fi P2P管理器和通道wifiP2pManager = (WifiP2pManager) context.getSystemService(Context.WIFI_P2P_SERVICE);channel = wifiP2pManager.initialize(context, Looper.getMainLooper(), null);// 创建意图过滤器并添加所需的意图动作IntentFilter intentFilter = new IntentFilter();intentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);intentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);intentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);intentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);// 注册广播接收器ContextCompat.registerReceiver(context, broadcastReceiver, intentFilter, ContextCompat.RECEIVER_EXPORTED);handler.postDelayed(new Runnable() {@Overridepublic void run() {try {discoverPeers();} catch (Exception e) {e.printStackTrace();}handler.postDelayed(this, 8888);}}, 88);}private final BroadcastReceiver broadcastReceiver = new BroadcastReceiver() {@Overridepublic void onReceive(Context context, Intent intent) {Log.i(TAG, "onReceive: " + intent.getAction());String action = intent.getAction();if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {// 获取连接信息WifiP2pInfo wifiP2pInfo = intent.getParcelableExtra(WifiP2pManager.EXTRA_WIFI_P2P_INFO);if (wifiP2pInfo != null) {new Thread(() -> {// 获取groupOwnerAddressInetAddress groupOwnerAddress = wifiP2pInfo.groupOwnerAddress;// 在这里可以使用groupOwnerAddress进行相应的操作if (groupOwnerAddress != null) {String hostAddress = groupOwnerAddress.getHostAddress();String hostName = groupOwnerAddress.getHostName();byte[] address = groupOwnerAddress.getAddress();String canonicalHostName = groupOwnerAddress.getCanonicalHostName();Log.i(TAG, "onReceive: get host address:" + hostAddress + "; " + hostName + "; " + address + "; " + canonicalHostName);// start socket connectotherClientIp = hostAddress;if (!TextUtils.isEmpty(otherClientIp)) {new Handler(Looper.getMainLooper()).post(() -> Toast.makeText(context.getApplicationContext(), "获取鬣主任ip", Toast.LENGTH_LONG).show());}}}).start();}}}};public void send(byte[] buf) {// 广播 都接受得到Log.i(TAG, "send: other client ip:" + otherClientIp);if (udp == null || otherClientIp == null) return;new Thread(() -> {String substring = otherClientIp.substring(0, otherClientIp.lastIndexOf("."));substring = substring + ".255";udp.sendAction(buf, substring);}).start();}@SuppressLint("MissingPermission")public void discoverPeers() throws Exception {wifiP2pManager.discoverPeers(channel, new WifiP2pManager.ActionListener() {@Overridepublic void onSuccess() {Log.i(TAG, "onSuccess: scan wifi node");}@Overridepublic void onFailure(int i) {Log.i(TAG, "onFailure: No nodes scanned");}});}@SuppressLint("MissingPermission")public void connectToPeer() {Log.i(TAG, "connectToPeer: start connect");wifiP2pManager.requestPeers(channel, wifiP2pDeviceList -> {List<WifiP2pDevice> deviceList = new ArrayList<>(wifiP2pDeviceList.getDeviceList());Log.i(TAG, "connectToPeer: item count:" + deviceList.size());if (deviceList.size() == 0) {return;}for (WifiP2pDevice item : deviceList) {Log.i(TAG, "connectToPeer: item name:" + item.deviceName + "; " + item.deviceAddress);// 创建连接配置WifiP2pConfig config = new WifiP2pConfig();config.deviceAddress = item.deviceAddress;connectItem(config, item);}});}@SuppressLint("MissingPermission")private void connectItem(WifiP2pConfig config, WifiP2pDevice item) {try {wifiP2pManager.connect(channel, config, new WifiP2pManager.ActionListener() {@Overridepublic void onSuccess() {Log.i(TAG, "onSuccess: Link successful for:" + item.deviceName + "; " + item.deviceAddress);}@Overridepublic void onFailure(int reasonCode) {Log.i(TAG, "onFailure: Link failure for:" + item.deviceName + "; " + item.deviceAddress);}});} catch (Exception e) {e.printStackTrace();Log.i(TAG, "getDevices: connect item error:" + e.getMessage());}}private void receiveAction(byte[] buffer, int len, String ip) {Log.i(TAG, "receiveAction: ip:" + ip + "; len:" + len);}public void release() {handler.removeCallbacksAndMessages(null);if (udp != null) {udp.release();udp = null;}try {context.unregisterReceiver(broadcastReceiver);} catch (Exception e) {e.printStackTrace();Log.i(TAG, "release: error:" + e.getMessage());}try {if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O_MR1) channel.close();} catch (Exception e) {e.printStackTrace();Log.i(TAG, "release:close channel error:" + e.getMessage());}}
}

udp 通讯类：

import android.util.Log;import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;public class SyncUDP implements Runnable {private static final String TAG = "ReceiveUDP";private Thread thread;private DatagramSocket socket;private OnUpdateListener listener;private int port;public void setListener(OnUpdateListener listener) {this.listener = listener;}public void release() {if (thread != null && !thread.isInterrupted())thread.interrupt();listener = null;closeSocket();if (thread != null) {try {thread.join();} catch (Exception e) {e.printStackTrace();}thread = null;}}public SyncUDP(int port) {this.port = port;thread = new Thread(this);thread.start();}public void sendAction(byte[] buf, String ip) {if (socket == null || socket.isClosed()) return;try {DatagramPacket sendPacket = new DatagramPacket(buf, buf.length);sendPacket.setAddress(InetAddress.getByName(ip));sendPacket.setPort(port);socket.send(sendPacket);} catch (Exception e) {e.printStackTrace();Log.i(TAG, "sendAction: send package error:" + e.getMessage());}}@Overridepublic void run() {while (!Thread.interrupted()) {try {byte[] by = new byte[16];socket = new DatagramSocket(port);socket.setBroadcast(true);while (!Thread.interrupted()) {try {// receive dataDatagramPacket receivePacket = new DatagramPacket(by, by.length);Log.i(TAG, "run: start wait package");// Join threadsocket.receive(receivePacket);String ip = receivePacket.getAddress().getHostAddress();Log.i(TAG, "run: get package len:" + receivePacket.getLength() + "; ip:" + ip);if (listener != null)listener.onUpdateUI(receivePacket.getData(), receivePacket.getLength(), ip);} catch (Exception e) {e.printStackTrace();break;}}closeSocket();} catch (Exception e) {e.printStackTrace();}}closeSocket();}private void closeSocket() {if (socket != null) {if (!socket.isClosed()) {try {socket.close();} catch (Exception e) {e.printStackTrace();}}socket = null;}}public interface OnUpdateListener {void onUpdateUI(byte[] buffer, int len, String ip);}
}