利用可能なwifiネットワークを取得してAndroidのリストに表示する方法

この例は、利用可能なWi-Fiネットワークを取得し、Androidのリストに表示する方法を示しています

ステップ1 − Android Studioで新しいプロジェクトを作成し、[ファイル]⇒[新しいプロジェクト]に移動して、新しいプロジェクトを作成するために必要なすべての詳細を入力します。

ステップ2 −次のコードをres / layout/activity_main.xmlに追加します。

<?xml version = "1.0" encoding = "utf-8"?>
<RelativeLayout xmlns:android = "https://schemas.android.com/apk/res/android"
   xmlns:tools = "https://schemas.android.com/tools"
   android:layout_width = "match_parent"
   android:layout_height = "match_parent"
   android:layout_margin = "16dp"
   android:orientation = "vertical"
   tools:context = ".MainActivity">
   <ListView
      android:id = "@+id/wifiList"
      android:layout_width = "match_parent"
      android:layout_height = "match_parent"
      android:layout_above = "@+id/scanBtn" />
   <Button
      android:id = "@+id/scanBtn"
      android:layout_width = "match_parent"
      android:layout_height = "50dp"
      android:layout_alignParentBottom = "true"
      android:layout_gravity = "bottom"
      android:layout_margin = "15dp"
      android:text = "Scan WiFi" />
</RelativeLayout>

ステップ3 −次のコードをsrc / MainActivity.java

package com.example.myapplication;

import android.Manifest;
import android.content.Context;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.net.wifi.WifiManager;
import android.os.Build;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
   private ListView wifiList;
   private WifiManager wifiManager;
   private final int MY_PERMISSIONS_ACCESS_COARSE_LOCATION = 1;
   WifiReceiver receiverWifi;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      wifiList = findViewById(R.id.wifiList);
      Button buttonScan = findViewById(R.id.scanBtn);
      wifiManager = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);
      if (!wifiManager.isWifiEnabled()) {
         Toast.makeText(getApplicationContext(), "Turning WiFi ON...", Toast.LENGTH_LONG).show();
         wifiManager.setWifiEnabled(true);
      }
      buttonScan.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_COARSE_LOCATION)
               ! = PackageManager.PERMISSION_GRANTED) {
               ActivityCompat.requestPermissions(
               MainActivity.this, new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, MY_PERMISSIONS_ACCESS_COARSE_LOCATION);
            } else {
               wifiManager.startScan();
            }
         }
      });
   }
   @Override
   protected void onPostResume() {
      super.onPostResume();
      receiverWifi = new WifiReceiver(wifiManager, wifiList);
      IntentFilter intentFilter = new IntentFilter();
      intentFilter.addAction(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION);
      registerReceiver(receiverWifi, intentFilter);
      getWifi();
   }
   private void getWifi() {
      if (Build.VERSION.SDK_INT > = Build.VERSION_CODES.M) {
         Toast.makeText(MainActivity.this, "version> = marshmallow", Toast.LENGTH_SHORT).show();
         if (ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.ACCESS_COARSE_LOCATION)
            ! = PackageManager.PERMISSION_GRANTED) {
            Toast.makeText(MainActivity.this, "location turned off", Toast.LENGTH_SHORT).show();
            ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.ACCESS_COARSE_LOCATION},
               MY_PERMISSIONS_ACCESS_COARSE_LOCATION);
         } else {
            Toast.makeText(MainActivity.this, "location turned on", Toast.LENGTH_SHORT).show();
            wifiManager.startScan();
         }
      } else {
         Toast.makeText(MainActivity.this, "scanning", Toast.LENGTH_SHORT).show();
         wifiManager.startScan();
      }
   }
   @Override
   protected void onPause() {
      super.onPause();
      unregisterReceiver(receiverWifi);
   }
   @Override
   public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
      super.onRequestPermissionsResult(requestCode, permissions, grantResults);
      switch (requestCode) {
         case MY_PERMISSIONS_ACCESS_COARSE_LOCATION:
         if (grantResults.length > 0 && grantResults[0] = = PackageManager.PERMISSION_GRANTED) {
            Toast.makeText(MainActivity.this, "permission granted", Toast.LENGTH_SHORT).show();
            wifiManager.startScan();
         } else {
            Toast.makeText(MainActivity.this, "permission not granted", Toast.LENGTH_SHORT).show();
            return;
         }
         break;
      }
   }
}

ステップ4 −次のコードをsrc / WifiReceiver

package com.example.myapplication;

import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.net.wifi.ScanResult;
import android.net.wifi.WifiManager;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.List;

class WifiReceiver extends BroadcastReceiver {
   WifiManager wifiManager;
   StringBuilder sb;
   ListView wifiDeviceList;
   public WifiReceiver(WifiManager wifiManager, ListView wifiDeviceList) {
      this.wifiManager = wifiManager;
      this.wifiDeviceList = wifiDeviceList;
   }
   public void onReceive(Context context, Intent intent) {
      String action = intent.getAction();
      if (WifiManager.SCAN_RESULTS_AVAILABLE_ACTION.equals(action)) {
         sb = new StringBuilder();
         List<ScanResult> wifiList = wifiManager.getScanResults();
         ArrayList<String> deviceList = new ArrayList<>();
         for (ScanResult scanResult : wifiList) {
            sb.append("\n").append(scanResult.SSID).append(" - ").append(scanResult.capabilities);
            deviceList.add(scanResult.SSID + " - " + scanResult.capabilities);
         }
         Toast.makeText(context, sb, Toast.LENGTH_SHORT).show();
         ArrayAdapter arrayAdapter = new ArrayAdapter(context, android.R.layout.simple_list_item_1, deviceList.toArray());
         wifiDeviceList.setAdapter(arrayAdapter);
      }
   }
}

ステップ5 −次のコードをandroidManifest.xmlに追加します

<?xml version = "1.0" encoding = "utf-8"?>
<manifest xmlns:android = "https://schemas.android.com/apk/res/android"
   package = "com.example.myapplication">
   <uses-permission android:name = "android.permission.ACCESS_COARSE_LOCATION" />
   <uses-permission android:name = "android.permission.ACCESS_WIFI_STATE" />
   <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>

アプリケーションを実行してみましょう。実際のAndroidモバイルデバイスをコンピューターに接続していると思います。 android studioからアプリを実行するには、プロジェクトのアクティビティファイルの1つを開き、ツールバーの[実行]アイコンをクリックします。オプションとしてモバイルデバイスを選択し、デフォルトの画面を表示するモバイルデバイスを確認します–