WiFi getSSID() 总是 returns “<unknown ssid>”

Question

这个问题已经被很多人问过，但对他们有效的解决方案对我不起作用。我已经在 Android 8.1 和 Android 9.0 上测试过，但无法获取 SSID 的名称。

用于获取 WiFi 状态更改的广播接收器：

private final BroadcastReceiver mReceiver = new BroadcastReceiver() {
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if(intent.getAction().equals(WifiManager.WIFI_STATE_CHANGED_ACTION) ||
                intent.getAction().equals(ConnectivityManager.CONNECTIVITY_ACTION) ||
                intent.getAction().equals(WifiManager.SUPPLICANT_STATE_CHANGED_ACTION) ||
                intent.getAction().equals(WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION) ||
                intent.getAction().equals(WifiManager.NETWORK_STATE_CHANGED_ACTION)) {
            setWifiIndicator();
        }
    }
};

接收器在 onCreate 中注册并在 onDestroy 中取消注册，我认为这是正确的，并且在调用接收器时我看到了日志行。

在onCreate中：

IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(ScannerService.ACTION_READ_SCANNER);
intentFilter.addAction(WifiManager.WIFI_STATE_CHANGED_ACTION);
intentFilter.addAction(WifiManager.SUPPLICANT_CONNECTION_CHANGE_ACTION);
intentFilter.addAction(WifiManager.NETWORK_STATE_CHANGED_ACTION);
intentFilter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
intentFilter.addAction(WifiManager.SUPPLICANT_STATE_CHANGED_ACTION);
registerReceiver(mReceiver, intentFilter);
setWifiIndicator();

setWifiIndicator是这样实现的：

private void setWifiIndicator() {
    ConnectivityManager connMgr = (ConnectivityManager)getSystemService(Context.CONNECTIVITY_SERVICE);
    //getApplicationContext solves memory leak issues prior to Android N (must use Application Context to get wifi system service.
    WifiManager wifiMgr = (WifiManager)getApplicationContext().getSystemService(Context.WIFI_SERVICE);
    ImageView wifiIndicator = (ImageView)findViewById(R.id.wifi_indicator);
    TextView wifiSSID = (TextView)findViewById(R.id.wifi_ssid);

    try {
        if (wifiMgr != null) {
            if (wifiMgr.isWifiEnabled()) {
                //wifi is enabled.  toggle on wifi indicator.
                wifiIndicator.setImageResource(R.drawable.wifi_indicator);
                String ssid = wifiMgr.getConnectionInfo().getSSID();
                if (ssid != null) {
                    Log.v(this.getClass().getSimpleName(), "SSID: " + ssid + "  Supplicant State: " + info.getSupplicantState());
                    wifiSSID.setText(ssid);
                }
            } else {
                //wifi is disabled.  toggle off wifi indicator.
                wifiSSID.setText("");

                //check for 3G
                NetworkInfo mobileInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
                if (mobileInfo != null && mobileInfo.getState().equals(NetworkInfo.State.CONNECTED)) {
                    wifiIndicator.setImageResource(R.drawable.cellular_indicator);
                } else {
                    wifiIndicator.setImageResource(R.drawable.down_indicator);
                }
            }
        } else {
            //check for 3G
            NetworkInfo mobileInfo = connMgr.getNetworkInfo(ConnectivityManager.TYPE_MOBILE);
            if (mobileInfo != null && mobileInfo.getState().equals(NetworkInfo.State.CONNECTED)) {
                wifiIndicator.setImageResource(R.drawable.cellular_indicator);
            } else {
                wifiIndicator.setImageResource(R.drawable.down_indicator);
            }
        }
    } catch(Exception e) {
        //catching anything thrown in this block just so it doesn't crash the program unnecessarily
        e.printStackTrace();
    }
}

我的应用程序已经获得 ACCESS_COARSE_LOCATION 的许可，但我还添加了 ACCESS_FINE_LOCATION 以防万一。 getSSID() 直到返回 <unknown ssid>。

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.GET_TASKS" />

可能跟编译目标SDK有关？我这里真的是一窍不通

gradle 文件:

应用插件：'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.noneofyour.business"
        minSdkVersion 15
        targetSdkVersion 28
        versionCode 59
        versionName "1.44"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'com.android.support:appcompat-v7:28.0.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation files('libs/android.jar')
}

Answer 1

您是否尝试检查 getSupplicantState() 是否为 COMPLETED？

if(wifiInfo.getSupplicantState() == SupplicantState.COMPLETED){
        String ssid = wifiInfo.getSSID();
        wifiSSID.setText(ssid);
}

另外，你在运行之前问过这个 BroadcastReceiver 还是在里面你可以做到：

 if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
    ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, LOCATION);
}else{setWifiIndicator();

Answer 2

Wi-Fi 权限

Android 8.0 和 Android 8.1:

成功调用 WifiManager.getScanResults() 需要以下任一权限：

• ACCESS_FINE_LOCATION • ACCESS_COARSE_LOCATION • CHANGE_WIFI_STATE

如果调用应用程序没有任何这些权限，调用将失败并出现 SecurityException。

Android 9:

成功调用 WifiManager.startScan() 需要满足以下所有条件：

• 您的应用具有 ACCESS_FINE_LOCATION 或 ACCESS_COARSE_LOCATION 权限。 • 您的应用程序拥有CHANGE_WIFI_STATE 权限。 • 设备上启用了位置服务（在“设置”>“位置”下）。

Android 10（API 29 级）及更高：

成功调用 WifiManager.startScan() 需要满足以下所有条件：

• 如果您的应用面向 Android10（API 级别 29）SDK 或更高版本，则您的应用具有 ACCESS_FINE_LOCATION 权限。

• 如果您的应用的目标 SDK 低于 Android 10（API 级别 29），则您的应用具有 ACCESS_COARSE_LOCATION 或 ACCESS_FINE_LOCATION 权限。

• 您的应用拥有 CHANGE_WIFI_STATE 权限。

• 设备上启用了位置服务（在“设置”>“位置”下）。

并实现Request User级权限

有关详细信息，请参阅此 link：https://developer.android.com/guide/topics/connectivity/wifi-scan#wifi-scan-permissions

XAMARIN FORMS 代码更改：

if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.O){
status = await CrossPermissions.Current.CheckPermissionStatusAsync(Permission.Location);
if (status != PermissionStatus.Granted)
{   
var results = await CrossPermissions.Current.RequestPermissionsAsync(new[] { Permission.Location });
status = results[Permission.Location];
}
}

WiFi getSSID() 总是 returns “<unknown ssid>”

WiFi getSSID() always returns "<unknown ssid>"

java

android

wifi