Question

我绑定了一个udp套接字，我正在尝试为特定地址编写一个udp数据报，所以这是我的代码：

UDP::UDP(QObject *parent) :
    QObject(parent)
{
    socket = new QUdpSocket(this);
    QObject::connect(socket,SIGNAL(bytesWritten(qint64)),this,SLOT(bytesWritten(qint64)));
    QObject::connect(socket,SIGNAL(readyRead()),this,SLOT(readyRead()));
}
void UDP::connect(int port){

if(socket->state()==QAbstractSocket::BoundState){
    qDebug()<<"already bound try to disconnect";
    socket->close();
}
     if(socket->bind(QHostAddress::Any,port,QAbstractSocket::ShareAddress|QAbstractSocket::Reuse    AddressHint)){
        qDebug()<< "listening";
        emit changeStatus("UDP: escutando("+QString::number(port)+")");
    }else{
        qDebug()<< "error no bind";
        emit changeStatus("UDP: erro no bind("+QString::number(port)+")");
    }
}

void UDP::bytesWritten(qint64 bytes){
    qDebug()<<"bytes written:"<<bytes;
    emit changeStatus("UDP: enviado");
}

void UDP::readyRead(){
    qDebug()<<"ready to read";
    QByteArray datagram;
    QHostAddress sender;
    quint16 senderPort;

    datagram.resize(socket->pendingDatagramSize());
    socket->readDatagram(datagram.data(),datagram.size(),&sender,&senderPort);
    qDebug()<< "datagram received from " << sender.toString();

    emit receivedUDPdata(datagram);

}
bool UDP::write(QString dest,int port, QString buffer, int size){
    char *finalOutput;
    finalOutput = new char[size];
    unsigned int j=0;

    for(unsigned int i=0;i<size;i++){
        if(buffer[i]== '\\'){
            switch (buffer.at(++i).toLatin1()){
            case 'r':
                finalOutput[j++] = '\r';
                break;
            case 'n':
                finalOutput[j++]= '\n';
                break;
            case 't':
                finalOutput[j++]='\t';
                break;
            case '\\':
                finalOutput[j++]='\\';
                break;
            }
        }else{
            finalOutput[j++]= buffer[i].toLatin1();
        }
    }
    socket->writeDatagram(finalOutput,j,QHostAddress(dest),port);
    if(!socket->waitForBytesWritten(2000)){
        qDebug() << "UDP Couldnt write.";
        emit changeStatus("UDP: Não foi possível escrever");
        return false;
    }
    return true;
}

变量dest是QString，但在我调用socket-＆gt; writeDatagram之后，它输入if如果它已经失败，但实际上写入了字节（我接收），并发出字节写入的信号。那么为什么要输入if子句？

ps（我测试了ip dest为127.0.0.1）和socket-＆gt; errorString（）打印“未知错误”

Answer 1

QAbstractSocket :: waitForBytesWritten（）用于调用write（）后的TCP套接字。

使用QUdpSocket，API是writeDatagram（），它立即发送（至少在Qt级别，OS我有一个缓冲区）。为了证明这一点，请参阅src / network / socket / qudpsocket.cpp中的writeDatagram（）的实现，它发出bytesWritten（已发送）;

因此在writeDatagram（）之后调用waitForBytesWritten（）没有意义。

QT 5.0 Qudpsocket不会触发waitforbyteswritten

1 个答案: