朋友们，我想找到所有可用的WiFi网络并将其显示在我尝试过的列表中，如下所示。但它不起作用。我已经编辑了我的代码，现在我得到了结果但是得到了我不需要的所有结果。我只需要列表中的wifi网络名称。
public class MainActivity extends Activity {
TextView mainText;
WifiManager mainWifi;
WifiReceiver receiverWifi;
List<ScanResult> wifiList;
StringBuilder sb = new StringBuilder();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mainText = (TextView) findViewById(R.id.tv1);
mainWifi = (WifiManager) getSystemService(Context.WIFI_SERVICE);
if (mainWifi.isWifiEnabled() == false)
{
// If wifi disabled then enable it
Toast.makeText(getApplicationContext(), "wifi is disabled..making it enabled",
Toast.LENGTH_LONG).show();
mainWifi.setWifiEnabled(true);
}
receiverWifi = new WifiReceiver();
registerReceiver(receiverWifi, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
mainWifi.startScan();
mainText.setText("Starting Scan...");
}
public boolean onCreateOptionsMenu(Menu menu) {
menu.add(0, 0, 0, "Refresh");
return super.onCreateOptionsMenu(menu);
}
public boolean onMenuItemSelected(int featureId, MenuItem item) {
mainWifi.startScan();
mainText.setText("Starting Scan");
return super.onMenuItemSelected(featureId, item);
}
protected void onPause() {
unregisterReceiver(receiverWifi);
super.onPause();
}
protected void onResume() {
registerReceiver(receiverWifi, new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
super.onResume();
}
// Broadcast receiver class called its receive method
// when number of wifi connections changed
class WifiReceiver extends BroadcastReceiver {
// This method call when number of wifi connections changed
public void onReceive(Context c, Intent intent) {
sb = new StringBuilder();
wifiList = mainWifi.getScanResults();
sb.append("\n Number Of Wifi connections :"+wifiList.size()+"\n\n");
for(int i = 0; i < wifiList.size(); i++){
sb.append(new Integer(i+1).toString() + ". ");
sb.append((wifiList.get(i)).toString());
sb.append("\n\n");
}
mainText.setText(sb);
}
}
}
答案 0 :(得分：37)
您需要创建一个BroadcastReceiver来收听Wifi扫描结果：
private final BroadcastReceiver mWifiScanReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context c, Intent intent) {
if (intent.getAction().equals(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION)) {
List<ScanResult> mScanResults = mWifiManager.getScanResults();
// add your logic here
}
}
}
在onCreate()中，您将分配mWifiManager并启动扫描：
mWifiManager = (WifiManager) getSystemService(Context.WIFI_SERVICE);
registerReceiver(mWifiScanReceiver,
new IntentFilter(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION));
mWifiManager.startScan();
getScanResults()才会返回数据。为此，请将以下两行之一添加到AndroidManifest.xml：
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
另请注意，在API 23+中，必须在运行时请求权限。 （对于实验室环境，您还可以在“设置”中手动授予权限，而不需要编码，但不建议最终用户应用。）
请注意，每次有新的扫描结果可用时，处理扫描结果的代码都会运行，从而更新结果。
答案 1 :(得分：7)
如果您的Android操作系统版本 6.0或更高，则您的应用程序必须在运行时请求以下权限（以下任一项）。
@Override
public void onResume()
{
super.onResume();
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M)
{
if(checkSelfPermission(Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED)
{
requestPermissions(new String[]{Manifest.permission.ACCESS_COARSE_LOCATION}, 87);
}
}
}
只需在活动的onResume方法中添加此代码
即可wifiManager.startScan();
Wifi.getScanResults（）将返回0结果。
包括我在内的很多人在Nexus 5手机中遇到过这个问题，并将其称为“＃34; bug＆＃34;。
可以通过
请求扫描public class WifiScanReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context context, Intent intent) {
if(intent.getAction().equals(WifiManager.SCAN_RESULTS_AVAILABLE_ACTION))
{
List<ScanResult> scanResults = wifimanager.getScanResults();
// Write your logic to show in the list
}
}
}
boolean startScan()返回 根据扫描是否已开始的事实立即生效或错误 成功与否。
但是它启动了一个异步事件 发送意图（ WifiManager.SCAN_RESULTS_AVAILABLE_ACTION ）时 扫描完成。由于扫描结果（异步事件结果）不会立即可用，您必须使用BroadcastReceiver注册您的活动。
以下是使用BroadcastReceiver读取这些结果（异步）的代码段。
typealias PlacesCompletion = ([GooglePlace]) -> Void
typealias PhotoCompletion = (UIImage?) -> Void
class GoogleDataProvider {
private var photoCache: [String: UIImage] = [:]
private var placesTask: URLSessionDataTask?
private var session: URLSession {
return URLSession.shared
}
let appDelegate = UIApplication.shared.delegate as! AppDelegate
func fetchPlacesNearCoordinate(_ coordinate: CLLocationCoordinate2D, radius: Double, types:[String], completion: @escaping PlacesCompletion) -> Void {
var urlString = "https://maps.googleapis.com/maps/api/place/nearbysearch/json?location=\(coordinate.latitude),\(coordinate.longitude)&radius=\(radius)&rankby=prominence&sensor=true&key=\(appDelegate.APP_ID)"
let typesString = types.count > 0 ? types.joined(separator: "|") : "food"
urlString += "&types=\(typesString)"
urlString = urlString.addingPercentEncoding(withAllowedCharacters: CharacterSet.urlQueryAllowed) ?? urlString
guard let url = URL(string: urlString) else {
completion([])
return
}
if let task = placesTask, task.taskIdentifier > 0 && task.state == .running {
task.cancel()
}
DispatchQueue.main.async {
UIApplication.shared.isNetworkActivityIndicatorVisible = true
}
placesTask = session.dataTask(with: url) { data, response, error in
var placesArray: [GooglePlace] = []
defer {
DispatchQueue.main.async {
UIApplication.shared.isNetworkActivityIndicatorVisible = false
completion(placesArray)
}
}
guard let data = data,
let json = try? JSON(data: data, options: .mutableContainers),
let results = json["results"].arrayObject as? [[String: Any]] else {
return
}
results.forEach {
let place = GooglePlace(dictionary: $0, acceptedTypes: types)
placesArray.append(place)
if let reference = place.photoReference {
self.fetchPhotoFromReference(reference) { image in
place.photo = image
}
}
}
}
placesTask?.resume()
}
func fetchPhotoFromReference(_ reference: String, completion: @escaping PhotoCompletion) -> Void {
if let photo = photoCache[reference] {
completion(photo)
} else {
let urlString = "https://maps.googleapis.com/maps/api/place/photo?maxwidth=200&photoreference=\(reference)&key=\(appDelegate.APP_ID)"
guard let url = URL(string: urlString) else {
completion(nil)
return
}
DispatchQueue.main.async {
UIApplication.shared.isNetworkActivityIndicatorVisible = true
}
session.downloadTask(with: url) { url, response, error in
var downloadedPhoto: UIImage? = nil
defer {
DispatchQueue.main.async {
UIApplication.shared.isNetworkActivityIndicatorVisible = false
completion(downloadedPhoto)
}
}
guard let url = url else {
return
}
guard let imageData = try? Data(contentsOf: url) else {
return
}
downloadedPhoto = UIImage(data: imageData)
self.photoCache[reference] = downloadedPhoto
}
.resume()
}
}
}
You can see this demo on BroadcastReceiver
答案 2 :(得分：6)
class WifiReceiver extends BroadcastReceiver {
public void onReceive(Context c, Intent intent) {
sb = new StringBuilder();
wifiList = mainWifi.getScanResults();
for (int i = 0; i < wifiList.size(); i++){
sb.append(new Integer(i+1).toString() + ".");
sb.append((wifiList.get(i)).SSID);
sb.append("\n");
}
mainText.setText(sb);
}
}