disconnect | 易学教程

QT信号和槽

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信号和槽是一种高级接口，应用于对象之间的通信，它是 QT 的核心特性。要正确的处理信号和槽，必须借助一个称为 moc（Meta Object Compiler）的 QT 工具，该工具是一个 C++ 预处理程序，它为高层次的事件处理自动生成所需要的附加代码。信号和槽能携带任意数量和任意类型的参数。我们可以将很多信号与单个的槽进行连接，也可以将单个的信号与很多的槽进行连接，（当这个信号被发射时，这些槽将会一个接一个地执行，但是它们执行的顺序将会是随机的、不确定的，我们不能人为地指定哪个先执行、哪个后执行。）甚至于将一个信号与另外一个信号相连接，这时无论第一个信号什么时候发射系统都将立刻发射第二个信号。总之，信号与槽构造了一个强大的部件编程机制。信号（Signals）信号只需要在头文件中做声明，不需要在cpp中实现。放在QT自定义关键字signals下，在此之前一定要加上Q_OBJECT宏！在编程中，一般使用的是控件内部定义好的信号。如：QTreeView类下的 Signals： 1 Q_SIGNALS: 2 void pressed(const QModelIndex &index); 3 void clicked(const QModelIndex &index); 4 void doubleClicked(const QModelIndex &index);

Call disconnect for asterisk

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问题 How to capture call disconnect for asterisk using PHPAGI ? For e.g. if user disconnects the call which event is invoked ? How to capture it ? 回答1: You can check the Return Results of your PHP-AGI API calls, for example stream_file returns -1 on hangup. You could also invoke another AGI Script on the h Extension in the Dialplan. If you have to clean up something, you could also register a Shutdown function. Another Approach is to register a Signal Handler which edmund long described in his

libtorrent-rasterbar can't download metadata using magnet links

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问题 I'm trying to download a remote metadata file (.torrent) using no-DHT, tracker-only behavior with libtorrent-rasterbar 0.16.13. Unfortunately, I get a lot of peer_disconnected errors; seeding from my program and downloading through clients such as BT or QBittorrent works. I'm using hex-encoded hashes, I don't know if this is the problem as libtorrent-rasterbar seems to support both Hex and Base32 hashes in the Magnet URI. Remember that I already have a tracker and I dont want to use DHT, but

Android连接蓝牙耳机播放音乐

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参考： Android实现主动连接蓝牙耳机具体实现： private static final String TAG = "BluetoothA2DPTest"; private BroadcastReceiver mBroadcastReceiver; private BluetoothA2dp mBluetoothA2dp; private BluetoothAdapter mBluetoothAdapter; private String DEVICE_NAME = "KUWO_K1"; private BluetoothDevice mBluetoothDevice; private MediaPlayer mMediaPlayer; private void initParameters(){ mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter(); if(mBluetoothAdapter == null){ Log.e(TAG,"have no bluetooth adapter."); return; } if(!mBluetoothAdapter.isEnabled()){ mBluetoothAdapter.enable(); }else{ //开始搜索附近蓝牙 startDiscovery(); /

Using Android API23 Call and Call.Details Class to get Disconnect Cause for Calls

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问题 All i am trying to do is to get the reason why a call was disconnected. I have searched but i am unable to find any solution for API level under 23. but in API 23 we have; https://developer.android.com/reference/android/telecom/Call.html https://developer.android.com/reference/android/telecom/Call.Details.html Call.Details.getDisconnectCause() returns the Disconnect Cause object but i am unable to understand how i can use use the CALL class or DETAILS class or which broadcasts to use to get

TcpClient disconnect during async read

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问题 I have a few questions about finishing a tcp connection. A client connects to my server using Tcp, after accepting the client with listener.BeginAcceptTcpClient(ConnectionEstabilishedCallback, null); , I start to read with networkStream.BeginRead(....) . What happens when the client disconnects while I wait for a message? (e.g. it loses power, internet, etc) How do I know when it happens? If after a successful read, I do some stuff, and then call networkStream.Close(); client.Close(); What

TcpClient disconnect during async read

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Android InputStream Internet Disconnect

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问题 In my Android program, I have some code that downloads a file. This works fine, but since on a cell phone, you can be disconnected at any time, I need to change it do it reconnects and resumes the download when you are halfway through and somebody calls/you lose cell reception/etc. I cannot figure out how to detect the InputStream has stopped working. See the code below: InputStream in = c.getInputStream(); byte[] buffer = new byte[8024]; int len1 = 0; while ( (len1 = in.read(buffer)) > 0 ) {

How can I detect a USB disconnect event? (Windows, .NET C# application)

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问题 Currently how I do this is I poll for a masked list of USB devices (masked specifically for the device I'm working with) and if it's there, I continue, if not then I notify the user that the device is not connected. The method for getting a list of USB devices is provided for me through a USB peripheral controller chip manufacturer's .NET library. Is there an event somewhere for a USB device disconnect? 回答1: I ended up using this: http://msdn.microsoft.com/en-us/library/aa363480(VS.85).aspx

Paho's MQTT client disconnects after the device locks

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问题 I'm currently working on a small "Panic Button" app supposed to operate in a medical facility. As one of the project's assumptions is to be Internet-independent, I've decided to go for MQTT with a server set up in the local WLAN. I've implemented the Paho Android Service and it works pretty good. Up to a certain point. Once I lock the device and turn off the sreen, exactly after one minute the client gets disconnected. As I've set MQTT options to KeepAlive interval of 30s, this must be caused