微信小程序的API可以说是越来越强大了，UDP通信也有了。

近期，有个项目可能要用到小程序，刚好提前研究学习调研，顺便写个简单例子总结一下。

通信效果展示

小程序端 QT端

小程序UDP通信这一块可以说是很简单了就一个UDPSocket实例。然后bind()方法绑定端口，send()方法发送数据，close()方法关闭通信，onMessage()方法监听消息等等，具体可以去看文档。

既然是通信，那么至少得有两个参与者，这里我以小程序为Server端，QT应用程序为Client端。

小程序为Server端：

固定IP：不定
端口号：不定

小程序UDP通信，Server端蛮简单：
创建UDPSocket实例，bind()方法绑定端口，onListening()方法监听，onMessage()方法接收消息，send()方法发送数据，close()方法关闭通信，onMessage()方法监听消息等等，具体可以去看官方文档。

  initUdpSocket() {
    this.data.udpSocket = wx.createUDPSocket();
    if (this.data.udpSocket === null) {
      console.log('暂不支持')
      return ;
    }

    const locationPort = this.data.udpSocket.bind()
    this.setData({
      'locationUrl.port': locationPort
    })

    this.data.udpSocket.onListening(function(res){
      console.log('监听中Res ===' + res)
    })

    let that = this
    this.data.udpSocket.onMessage(function (res) {
      console.log('remoteInfo ===' + res.remoteInfo)
      console.log('remoteInfo.size ===' + res.remoteInfo.size)
      if (res.remoteInfo.size > 0) {
        console.log('UDP接收数据 ' + res.remoteInfo.size + ' 字节：' + JSON.stringify(res, null, '\t'))
  
        let unit8Arr = new Uint8Array(res.message);
        let encodedString = String.fromCharCode.apply(null, unit8Arr);
        let escStr = escape(encodedString);
        let decodedString = decodeURIComponent(escStr);
        
        console.log('str==='+decodedString)
        let list = that.data.messageList
        let obj = {
          text: decodedString,
          from: 1
        }
        list.push(obj)
        that.setData({
          messageList: list
        })
      }
    })
  },

sendMessage() {
    if (this.data.mydata.isSend) {
      return ;
    }
    this.data.mydata.isSend = true
    let ip = this.data.mydata.remoteUrl.ip
    let port = this.data.mydata.remoteUrl.port
    let message = this.data.mydata.message
    if (message.trim() === '') {
      wx.showToast({
        title: '请输入内容',
      })
      this.data.mydata.isSend = false
      return ;
    }

    this.data.udpSocket.send({
      address: ip,
      port: port,
      message: message
    })

    this.data.mydata.isSend = false
    let list = this.data.messageList
    let obj = {
      text: message,
      from : 2
    }
    list.push(obj)
    this.setData({
      messageList : list
    })
  },

QT应用程序为Client端：

固定IP：如，192.168.1.103
端口号：6510

QT端UDP通信，Server也简单：

创建QUdpSocket

void AppUdp::createSocket()
{
    if (mUdpSocket != nullptr)
    {
        delete mUdpSocket;
        mUdpSocket = nullptr;
    }
    mUdpSocket = new QUdpSocket();
}

绑定端口：6510

void AppUdp::listen(unsigned short listenPort)
{
    // udp端口监听（线程安全）
    if (listenPort != 0)
    {
        appConfig->clientPort = listenPort;
    }

    // signalListenSuccess信号返回监听结果，listenSuccess属性可获取
    emit signalSelfListenPort();
}

void AppUdp::slotSelfListenPort()
{
    bool result = mUdpSocket->bind(QHostAddress::Any, appConfig->clientPort);
    this->setListenSuccess(result);
    if (result)
    {
        QLOG_INFO() << "bind success ======= Listen port:" + QString("%1").arg(appConfig->clientPort);
    }
    else
    {
        QLOG_FATAL() << "bind fail ======= Listen port:" + QString("%1").arg(appConfig->clientPort);
    }

    emit signalListenSuccess(result);
}

udp监听回调

void AppUdp::slotUdpSocketReceive()
{
    while (mUdpSocket->hasPendingDatagrams())
    {
        QHostAddress targetaddr;
        unsigned short targetPort;
        QByteArray datagram;
        datagram.resize(static_cast<int>(mUdpSocket->pendingDatagramSize()));
        mUdpSocket->readDatagram(datagram.data(), datagram.size(), &targetaddr, &targetPort);
        if (datagram.size() > 0)
        {
            emit signalUdpSocketReceiveData(targetaddr, targetPort, datagram);
        }
    }
}

QT端作了一个信息回馈，

void AppUdpClientServer::slotSelfWriteControl(const QByteArray data)
{
    QHostAddress address;
    address.setAddress(appConfig->serverIp);
    qint64 result = mUdpSocket->writeDatagram(data, address, appConfig->serverPort);

    if (result == -1)
    {
        QLOG_WARN() << "Send ip=" << appConfig->serverIp << "Send port=" << appConfig->serverPort << " result=" << result
                    << " udpState=" << mUdpSocket->state();

        createSocket();
        result = mUdpSocket->writeDatagram(data, address, appConfig->serverPort);
        if (result == -1)
        {
            QLOG_FATAL() << "Send ip=" << appConfig->serverIp << "Send port=" << appConfig->serverPort << " result=" << result
                         << " udpState=" << mUdpSocket->state();
            emit signalUdpSocketError();
        }
    }
}

回馈前，需要在Client接收数据是解析，IP和端口号

void AppUdpServerControl::slotClienttReceiveData(QHostAddress ipAddr, unsigned short port, QByteArray bytes)
{
    QMutexLocker locker(m_mutex);
    QString qStrIpAddrTemp = ipAddr.toString();
    QString qStrIpAddr;

    int i = 0;

    // 填充ip地址
    for (i = 7; qStrIpAddrTemp[i] != '\0'; i++)
    {
        qStrIpAddr[i - 7] = qStrIpAddrTemp[i];
    }

    QLOG_INFO() << "Ip[" << qStrIpAddr << "]. ort[" << port << "]. Size[" << bytes.size() << "]." << endl;
    QString keyCmd                                 = QString(bytes);
    appUdpClientServer->getAppConfig()->serverIp   = qStrIpAddr;
    appUdpClientServer->getAppConfig()->serverPort = port;

    if ("1" == keyCmd)
    {
        // TODO 一键回原点
        motorSystem->getSystemMotor()->getParentBoard()->returnHome();
    }
    else if ("2" == keyCmd)
    {
        // TODO 单轴回原点
        motorSystem->getControl()->returnHome();
    }
    else if ("3" == keyCmd)
    {
        // TODO 下降5mm
        motorSystem->getControl()->moveByType(5);
        const QByteArray data = "中文zhongwen";
        appUdpClientServer->udpWriteData(data);
    }

    QLOG_INFO() << "keyCmd == " << keyCmd << "]." << endl;
}

感谢大家看完微信小程序UDP通信篇，更多精彩等待下次创作，你最大的支持就是：赞同+评论+赞赏+...，关注我。

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