如何在安卓上使用 WiFi 直连？

此示例演示如何在安卓上使用 WiFi 直连

步骤 1− 在 Android Studio 中新建一个项目，依次转到文件 ⇒ 新建项目，并填写所有必要详细信息以新建一个项目。

步骤 2− 将以下代码添加到 res/layout/activity_main.xml。

<?xml version = "1.0" encoding = "utf-8"?>
<LinearLayout xmlns:android = "http://schemas.android.com/apk/res/android"
   xmlns:tools = "http://schemas.android.com/tools"
   android:layout_width = "match_parent"
   android:layout_height = "match_parent"
   android:layout_margin = "16dp"
   android:orientation = "vertical"
   tools:context = ".MainActivity">
   <Button
      android:text = "Turn on wifi"
      android:id = "@+id/button"
      android:layout_width = "wrap_content"
      android:layout_height = "wrap_content"
      android:layout_gravity = "center" />
</LinearLayout>

步骤 3− 将以下代码添加到 src/WifiDirectBroadcastReceiver

package com.example.myapplication;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.wifi.p2p.WifiP2pManager;
import android.widget.Toast;

public class WifiDirectBroadcastReceiver extends BroadcastReceiver {
   WifiP2pManager wifiP2pManager;
   WifiP2pManager.Channel channel;
   MainActivity activity;
   public WifiDirectBroadcastReceiver(WifiP2pManager wifiP2pManager, WifiP2pManager.Channel channel, MainActivity activity) {
      this.wifiP2pManager = wifiP2pManager;
      this.channel = channel;
      this.activity = activity;
   }
   @Override
   public void onReceive(Context context, Intent intent) {
      String action = intent.getAction();
      if (WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION.equals(action)) {
         int state = intent.getIntExtra(WifiP2pManager.EXTRA_WIFI_STATE, -1);
         if (state = = WifiP2pManager.WIFI_P2P_STATE_ENABLED) {
            Toast.makeText(activity, "Wifi on", Toast.LENGTH_SHORT).show();
         } else {
            Toast.makeText(activity, "Wifi off", Toast.LENGTH_SHORT).show();
         }
      } else if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) {
      } else if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {
      } else if (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action)) {
      }
   }
}

步骤 4− 将以下代码添加到 src/MainActivity.java

package com.example.myapplication;
import android.content.BroadcastReceiver;
import android.content.IntentFilter;
import android.net.wifi.WifiManager;
import android.net.wifi.p2p.WifiP2pManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
   TextView text;
   Button button;
   WifiManager mWifiMgr;
   WifiP2pManager mWifiP2pMgr;
   WifiP2pManager.Channel mChannel;
   BroadcastReceiver mReceiver;
   IntentFilter mIntentFilter;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      button = findViewById(R.id.button);
      mWifiMgr = (WifiManager) getApplicationContext().getSystemService(WIFI_SERVICE);
      mWifiMgr.setWifiEnabled(false);
      mWifiP2pMgr = (WifiP2pManager) getApplicationContext().getSystemService(WIFI_P2P_SERVICE);
      mChannel = mWifiP2pMgr.initialize(this, getMainLooper(), null);
      mReceiver = new WifiDirectBroadcastReceiver(mWifiP2pMgr, mChannel, this);
      mIntentFilter = new IntentFilter();
      mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);
      mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);
      mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);
      mIntentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);
      button.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            if (mWifiMgr.isWifiEnabled()) {
               mWifiMgr.setWifiEnabled(false);
               button.setText("Turn on wifi");
            } else {
               mWifiMgr.setWifiEnabled(true);
               button.setText("Turn off wifi");
            }
         }
      });
   }
   @Override
   protected void onResume() {
      super.onResume();
      registerReceiver(mReceiver, mIntentFilter);
   }
   @Override
   protected void onPause() {
      super.onPause();
      unregisterReceiver(mReceiver);
   }
}

步骤 5 − 将以下代码添加到 androidManifest.xml 中

<?xml version = "1.0" encoding = "utf-8"?>
<manifest xmlns:android = "http://schemas.android.com/apk/res/android"
   package = "com.example.myapplication">
   <uses-permission android:name = "android.permission.CHANGE_WIFI_STATE" />
   <application
      android:allowBackup = "true"
      android:icon = "@mipmap/ic_launcher"
      android:label = "@string/app_name"
      android:roundIcon = "@mipmap/ic_launcher_round"
      android:supportsRtl = "true"
      android:theme = "@style/AppTheme">
      <activity android:name = "com.example.myapplication.MainActivity">
         <intent-filter>
            <action android:name = "android.intent.action.MAIN" />
            <category android:name = "android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>

让我们尝试运行应用程序。我假设你已将实际的安卓移动设备连接到计算机。从 Android Studio 运行应用，打开项目的某个活动文件，然后单击工具栏中的运行图标。选择移动设备作为选项，然后检查将显示默认屏幕的移动设备 –