Question

许多人已经问过这个问题，但是对他们有用的解决方案对我却不起作用。我已经在Android 8.1和Android 9.0上进行了测试，但无法获取SSID的名称。

用于更改WiFi状态的广播接收器：

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();
        }
    }
};

接收器已在onCreate中注册，并在onDestroy中未注册，我认为这是正确的，并且在调用接收器时看到日志行。

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();
    }
}

我的应用已获得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" />

也许与编译目标SDK有关？我真的很笨。

渐变文件：

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);
}

此外，您是否在运行BroadcastReceiver之前甚至在内部就可以做到这一点？

 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

如果正在调用的应用没有这些权限，则调用将失败，并显示SecurityException。

Android 9：

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

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

Android 10（API级别29）及更高版本：

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

•如果您的应用程序针对的是Android 10（API级别29）SDK或更高版本，则您的应用程序具有ACCESS_FINE_LOCATION权限。

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

•您的应用拥有CHANGE_WIFI_STATE权限。

•在设备上启用了位置服务（在“设置”>“位置”下）。

并请求用户级别权限来实现

有关更多信息，请参见此链接：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（）始终返回“ <unknown ssid =”“>”

2 个答案: