【Android学习】WiFi扫描

 AndroidManifest.xml,增加2个权限声明

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.wifiscanner">

    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_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=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

activity_main.xml,增加一个

LinearLayout和ListView

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <ListView
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:id="@+id/list"></ListView>
    </LinearLayout>


</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.java

package com.example.wifiscanner;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;

import android.Manifest;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.pm.PackageManager;
import android.net.wifi.ScanResult;
import android.net.wifi.WifiManager;
import android.os.Build;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import java.sql.Time;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;

public class MainActivity extends AppCompatActivity {
    private List<String> wifilist = new ArrayList<>();
    private ListView listView;
    private WifiReceiver wifiReceiver;
    private ArrayAdapter adapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listView = findViewById(R.id.list);

   //     requestPermissions(new String[]{Manifest.permission.ACCESS_COARSE_LOCATION,Manifest.permission.ACCESS_WIFI_STATE},0x123);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M && checkSelfPermission(
                Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
            requestPermissions(new String[] { Manifest.permission.ACCESS_COARSE_LOCATION ,Manifest.permission.ACCESS_WIFI_STATE},0x123);

        } else {
            getWifiList();
            adapter = new ArrayAdapter(MainActivity.this,android.R.layout.simple_list_item_1,wifilist);
            listView.setAdapter(adapter);
        }
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION);
        intentFilter.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);
        wifiReceiver = new WifiReceiver();
        registerReceiver(wifiReceiver,intentFilter);
        final getWifilistHandler handler = new getWifilistHandler();
        new Timer().schedule(new TimerTask() {
            @Override
            public void run() {
                handler.sendEmptyMessage(0x123);
            }
        },0,1000);
    }
    public class getWifilistHandler extends Handler{
        @Override
        public void handleMessage(@NonNull Message msg) {
            if(msg.what == 0x123)
            {
                getWifiList();
                adapter.notifyDataSetChanged();
            }
            super.handleMessage(msg);
        }
    }
    public class WifiReceiver extends BroadcastReceiver{
        @Override
        public void onReceive(Context context, Intent intent) {
                getWifiList();
                adapter.notifyDataSetChanged();
//                if (wifilist != null){
//                    ArrayAdapter adapter = new ArrayAdapter(MainActivity.this,android.R.layout.simple_list_item_1,wifilist);
//                    listView.setAdapter(adapter);
//                }
        }
    }
    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        if (0x123 == requestCode && grantResults[0] == PackageManager.PERMISSION_GRANTED
                && grantResults[1] == PackageManager.PERMISSION_GRANTED)
        {
            getWifiList();
            adapter = new ArrayAdapter(MainActivity.this,android.R.layout.simple_list_item_1,wifilist);
            listView.setAdapter(adapter);
        }
     //   super.onRequestPermissionsResult(requestCode, permissions, grantResults);
    }

    public List<String> getWifiList() {
        WifiManager wifiManager = (WifiManager) getApplicationContext().getSystemService(WIFI_SERVICE);
        List<ScanResult> scanWifiList = wifiManager.getScanResults();
        wifilist.clear();
        if (scanWifiList != null && scanWifiList.size() > 0) {
            HashMap<String, Integer> signalStrength = new HashMap<String, Integer>();
            for (int i = 0; i < scanWifiList.size(); i++) {
                ScanResult scanResult = scanWifiList.get(i);
                if (!scanResult.SSID.isEmpty()) {
                    String key = scanResult.SSID + " " + scanResult.capabilities;
                    if (!signalStrength.containsKey(key)) {
                        signalStrength.put(key, i);
                        wifilist.add(scanResult.SSID+"
"+ scanResult.BSSID+"
" +String.valueOf(scanResult.level));
                    }
                }
            }
        }else {
            Log.e("Msg__---", "没有搜索到wifi");
        }
        return wifilist;
    }
}

开发中遇到一个问题，是ListView没有更新，调试发现apapter中数据已经更新，网上查找说要增加

　　adapter.notifyDataSetChanged();

增加后，依然显示不更新，最后检查发现adapter绑定的list地址发生了变化，导致更新界面出现了问题，最后修改了，可以正常更新

 

使用小米3，Android6.0，华为Mate10pro，Android9.0，Android Studio3.5，测试，小米3可以及时刷新，华为不行，要有段时间才能刷新，原因待查