1、使用QProcess和Ping

            QProcess *cmd = new QProcess;  
            #ifdef _TTY_ARMV4_  
            QString strArg = "ping -s 1 -c 1 " + b_tmpIpStr;        //linux平台下的格式  
            #else  
            QString strArg = "ping " + b_tmpIpStr + " -n 1 -w " + QString::number(m_timeoutInt) ;  //windows下的格式  
            #endif  
            cmd->start(strArg);  
            cmd->waitForReadyRead();  
            cmd->waitForFinished();  
            QString retStr = cmd->readAll();  
            if (retStr.indexOf("TTL") != -1)  
            {  
                qDebug() << m_curIpStr <<"is online!\n";  
            }  
            retStr.clear();

2、使用QTcpSocket连接

            QTcpSocket socket(0);
            socket.abort(); //取消原有连接
            socket.connectToHost(m_curIpStr,m_curPort); //建立一个TCP连接
            if(socket.waitForConnected(m_timeoutInt))
            {
                qDebug()<<m_curIpStr<<"is online\n";
            }
            socket.close();