我已经在 SO 上阅读了大量关于使用 WakeLock 和 WifiLock 的教程和帖子，但仍然没有解决我的问题。

我正在编写一个应用程序，当您启动它时，它的唯一作用是创建和启动(前台)服务。该服务运行两个线程，一个是 UDP 广播监听器(使用 java.io)，另一个是 TCP 服务器(使用 java.nio)。在服务的 onCreate 中，我获取了一个唤醒锁和一个 wifilock，并在 onDestroy 中释放了它们。

只要手机处于唤醒状态，一切正常，但是当显示屏关闭时，UDP 广播接收器停止接收广播消息，并且在我再次打开显示屏之前不会收到任何消息。实际上，这些锁根本不起作用，放置它们也没有区别……我哪里错了？我确定我在某个地方做了一些愚蠢的事情，但我自己找不到。

这是一些代码:

这是 Activity 所做的:

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    onlyStartService = true;
}@Override
protected void onStart() {
    super.onStart();
    Intent bIntent = new Intent(this, FatLinkService.class);
    getApplicationContext().startService(bIntent);
    getApplicationContext().bindService(bIntent, flConnection, BIND_AUTO_CREATE);
} 
// service connection to bind idle service
private ServiceConnection flConnection = new ServiceConnection() {
    public void onServiceConnected(ComponentName className, IBinder binder) {
       linkService.MyLinkBinder flBinder = (LinkService.MylinkBinder) binder;
       flServiceInstance = flBinder.getService();
       if (onlyStartService) {
           condLog("Service bound and finishing activity...");
           finish();
       }
    }
    public void onServiceDisconnected(ComponentName className) {
        flServiceInstance = null;
    }
}; 
@Override
protected void onStop() {
    super.onStop();

    if (fatFinish) {
        Intent bIntent = new Intent(this, FatLinkService.class);
        flServiceInstance.stopServices();
        flServiceInstance.stopForeground(true);
        flServiceInstance.stopService(bIntent);
        condLog("Service stop and unbound");
        flServiceInstance = null;
    }
    getApplicationContext().unbindService(flConnection);
}

服务是这样的:

public class LinkService extends Service {
    InetAddress iaIpAddr, iaNetMask, iaBroadcast;
    private final IBinder mBinder = new MyLinkBinder();
    private linklistenBroadcast flBroadServer = null;
    private linkTCPServer flTCPServer = null;
    private linkUDPClient flBroadClient = null;
    List<String> tokens = new ArrayList<String>();
    private PowerManager.WakeLock wakeLock;
    private WifiManager.WifiLock wifiLock;

public class MylLinkBinder extends Binder {
    lLinkService getService() { return LinkService.this; }
}

@Override
public IBinder onBind(Intent intent) {
    return mBinder;
}

@Override
public void onCreate() {
    super.onCreate();
    getLocks();
}

@Override
public int onStartCommand(Intent intent, int flags, int startId)
{        
    instantiateServices();
    // notifies presence to other fat devices
    condLog("Service notifying fat presence...");
    flBroadClient = new LinkUDPClient();
    flBroadClient.startSending(LinkProtocolConstants.BRCMD_PRESENCE + String.valueOf(LinkProtocolConstants.tcpPort), iaBroadcast, LinkProtocolConstants.brPort);
    return START_STICKY;
}

public void getLocks() {
    // acquire a WakeLock to keep the CPU running
    condLog("Acquiring power lock");
    WifiManager wm = (WifiManager) getApplicationContext().getSystemService(Context.WIFI_SERVICE);
    wifiLock = wm.createWifiLock(WifiManager.WIFI_MODE_FULL , "MyWifiLock");
    wifiLock.acquire();
    PowerManager pm = (PowerManager) getApplicationContext().getSystemService(Context.POWER_SERVICE);
    wakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "MyWakeLock");
    wakeLock.acquire();
}

public void stopServices() {
    if (flTCPServer != null)
        flTCPServer.stopServer();
    if (flBroadServer != null)
        flBroadServer.stopSelf();
}

private void instantiateServices() {
    populateAddresses(); // just obtain iaIpAddr  
    if (flTCPServer == null) {
        condLog("Instantiating TCP server");
        flTCPServer = new LinkTCPServer(iaIpAddr, FatLinkProtocolConstants.tcpPort);
        flTCPServer.execute();
    }
    if (flBroadServer == null) {
        condLog("Instantiating UDP broadcast server");
        Intent notifyIntent = new Intent(this, LinkMain.class); // this is the main Activity class
        notifyIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
        notifyIntent.setAction("FROM_NOTIFICATION");
        PendingIntent notifyPIntent = PendingIntent.getActivity(this, 0, notifyIntent, 0);

        Notification fixNotification = new Notification.Builder(getApplicationContext())
                .setContentTitle("Link")
                .setSmallIcon(R.mipmap.imgLink)
                .setContentIntent(notifyPIntent)
                .build();
        startForeground(1234, fixNotification);
        flBroadServer = new LinklistenBroadcast();
        flBroadServer.start();
    }
}

private final class LinklistenBroadcast extends Thread {
    private boolean bStopSelf = false;
    DatagramSocket socket;
    public void stopSelf() {
        bStopSelf = true;
        socket.close();
    }

    @Override
    public void run() {
        condLog( "Listening broadcast thread started");
        bStopSelf = false;
        try {
        //Keep a socket open to listen to all the UDP trafic that is destinated for this port
        socket = new DatagramSocket(null);
        socket.setReuseAddress(true);
        socket.setSoTimeout(LinkGeneric.BR_SOTIMEOUT_MILS);
        socket.setBroadcast(true);
        socket.bind(new InetSocketAddress(InetAddress.getByName("0.0.0.0"), FatLinkProtocolConstants.brPort));
        while (true) {
                condLog("Ready to receive broadcast packets...");
                //Receive a packet
                byte[] recvBuf = new byte[1500];

                DatagramPacket packet = new DatagramPacket(recvBuf, recvBuf.length);
                try {
                    socket.receive(packet);
                } catch (InterruptedIOException sException) {
                    condLog(sockExcept.toString());
                    break;
                } catch (SocketException sockExcept) {
                   condLog(sockExcept.toString());
                }
                if (bStopSelf) {
                    condLog("Broadcast server stopped...");
                    break;
                }
                int len = packet.getLength();
                String datarecvd = new String(packet.getData()).trim();
                //datarecvd = datarecvd.substring(0, len);
                //Packet received
                String message = new String(packet.getData()).trim();
                condLog("<<< broadcast packet received from: " + packet.getAddress().getHostAddress() + " on port: " + packet.getPort() + ", message: " + message);
                if (packet.getAddress().equals(iaIpAddr)) {
                    condLog("Ooops, it's me! discarding packet...");
                    continue;
                }
                else
                    condLog("<<< Packet received; data size: " + len + " bytes, data: " +  datarecvd);

                //See if the packet holds the right command (message)

                // protocol decode
                // here do some tuff
        } catch (IOException ex) {
            condLog(ex.toString());
        }

        if (socket.isBound()) {
            condLog( "Closing socket");
            socket.close();
        }
        condLog( "UDP server thread end.");
        flTCPServer = null;
        flBroadServer = null;
    }

    public boolean isThreadRunning() {
        return !bStopSelf;
    };
}

// Utility functions
public boolean checkBroadcastConnection (DatagramSocket socket, int timeOutcycles) {
    int tries = 0;
    while (!socket.isConnected()) {
        tries++;
        if (tries >= timeOutcycles)
            return false;
    }
    return true;
}

@Override
public void onDestroy() {
    super.onDestroy();
    if (wakeLock != null) {
        if (wakeLock.isHeld()) {
            wakeLock.release();                
        }
    }
    if (wifiLock != null) {
        if (wifiLock.isHeld()) {
            wifiLock.release();
        }
    }
}

最后，这是 list :

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="xxxxxx.ink" >
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
    <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.WRITE_SETTINGS" />
    <application
        android:allowBackup="true"
        android:icon="@mipmap/imgLinkmascotte"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".LinkMain"
            android:label="@string/app_name"
            android:theme="@android:style/Theme.Translucent.NoTitleBar.Fullscreen">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <service android:name=".LinkService" />
    </application>
</manifest>

• 我已阅读 this ，我怀疑问题是一样的，但它实际上发生在我试过的所有手机上(galaxy Tab 7.1，galaxy tag 10，Galaxy SIII，Galaxy Note 3 Neo，Galaxy SIII mini)从4.0 到 4.4。

• 我已经尝试过发布 here 的解决方案，但一切都变了(再次……有点令人沮丧)。

• 我什至尝试在我试过的所有手机中将“保持 wifi 选项处于待机状态”设置为“始终”，但仍然没有。

• 我研究了 WakeFulIntentService 类，它应该像每个人所说的那样工作，但我看不出我的代码有任何显着差异。

我真的希望有人能帮助我，从上周开始我就一直坚持这个问题。

编辑:根据 waqaslam 的回答，我检查了一个在 Wifi-Advaced 设置中有“Wifi 优化”选项的设备，当我取消该选项时它实际上可以正常工作。所以，现在，问题变成了:我可以在高级菜单中没有显示该选项的设备中禁用 Wifi 优化吗？正如我在下面的评论中所写，这似乎与 Android 版本无关，因为我有两台设备(都是三星)4.4.2，但它们没有显示该选项。

新编辑:从编辑过的 waqaslam 答案中，我尝试将 multicaSTLock 添加到我的服务中，但又发生了任何变化。这越来越烦人了，几乎没有什么简单明了的事情可以用 android 来做。

非常感谢 C.

最佳答案

我认为问题不在于 WakeLocks，而在于 Wi-Fi 设置。

在较新版本的 android 中，设置 -> Wi-Fi -> 高级 中有一个额外的设置 称为 Wi-Fi 优化，它(如果打开)会在显示屏关闭时禁用所有低优先级通信(如收听 UDP 广播)。

禁用该选项应该允许您的设备即使在显示器关闭时也能收听 UDP 广播。

您也可以使用 WifiManager.MulticastLock为了获得 WiFi 锁，应该在屏幕关闭时收听这些特殊广播。

WifiManager wifi = (WifiManager) this.getSystemService(Context.WIFI_SERVICE);
MulticastLock lock = wifi.createMulticastLock("lockWiFiMulticast");
lock.setReferenceCounted(false);
lock.acquire();

完成锁定后，调用:

lock.release();

此外，不要忘记将以下权限添加到您的 list 中:

<uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE"/>

更多信息，您可以阅读this .

关于java - 唤醒锁和 wifilock 不工作，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/28627928/