Qt 進程 QProcess

定義

The QProcess class is used to start external programs and to communicate with them.

QProcess類是用來啟動一個外部程式並與之通訊。 使用說明 開啟外部線程的3中方式

To start a process, pass the name and command line arguments of the program you want to run as arguments to start(). Arguments are supplied as individual strings in a QStringList.

Alternatively, you can set the program to run with setProgram() and setArguments(), and then call start() or open().

想要啟動一個進程，可以傳遞你想啟動的程式的名字和命令列參數作為參數傳遞給start()函數。參數作為QStringList中每一個單獨的字串。

或者，你可以通過setProgram()和setArguments()來設定該程式，然後調用start()或者open()啟動該程式。 啟動時在指定程式名時就附帶上參數

QProcess process;process.start("cmd /c ping 127.0.0.1");

啟動時分別指定函數名和參數列表

QProcess process;process.start("cmd", QStringList()<<"/c"<<"ping 127.0.0.1", QIODevice::ReadWrite);

分別指定函數名和參數，然後再啟動

QProcess process;process.setProgram("cmd");process.setArguments(QStringList()<<"/c"<<"ping 127.0.0.1");process.start(QIODevice::ReadWrite);

一次性讀取進程輸出

void readProcessAllOnce(bool processAutoExit) {    qDebug()<<"readProcessAllOnce, processAutoExit ="<<processAutoExit;    qDebug()<<"----------------------";    bool ret;    QProcess process;    QString command;    if(processAutoExit) {        command = "cmd /c ping 127.0.0.1";    } else {        command = "cmd /k ping 127.0.0.1";    }    process.start(command);    /*     * bool QProcess::waitForStarted(int msecs = 30000)     */    ret = process.waitForStarted();    qDebug()<<"waitForStarted"<<ret;    qDebug()<<QDateTime::currentDateTime();    /*     * 如果開啟的不是自動關閉的進程，那麼這裡最多可能會等待30秒     * bool QProcess::waitForFinished(int msecs = 30000)     */    ret = process.waitForFinished();    qDebug()<<QDateTime::currentDateTime();    qDebug()<<"waitForFinished"<<ret;    QByteArray byteArray = process.readAllStandardOutput();    QString str = QString::fromLocal8Bit(byteArray);    qDebug()<<str;    process.close();    qDebug()<<"";    qDebug()<<"======================";}

按行讀取進程輸出

void readProcessByLine() {    qDebug()<<"readProcessByLine";    qDebug()<<"----------------------";    bool ret;    QProcess process(0);    /*     * cmd /c 的命令執行完後會關閉視窗     * cmd /k 的命令執行完後不會關閉視窗     *     * aa && bb 就是執行aa，成功後再執行bb     * aa || bb 先執行aa，若執行成功則不再執行bb，若失敗則執行bb     * a  &  b  表示執行a再執行b，而無論a是否成功     */    process.start("cmd", QStringList()<<"/k"<<"ping 127.0.0.1"<<"&"<<"exit", QIODevice::ReadWrite);//    process.setProgram("cmd");//    process.setArguments(QStringList()<<"/k"<<"ping 127.0.0.1"<<"&"<<"exit");//    process.start(QIODevice::ReadWrite);    ret = process.waitForStarted();    qDebug()<<"waitForStarted"<<ret;    qint64 maxSize = 512;    char buffer[maxSize];    qint64 len;    while(true) {        /*         * 一個waitForReadyRead訊號可能輸出的是多行         */        ret = process.waitForReadyRead();        qDebug()<<"waitForReadyRead"<<ret;        if(!ret) {            break;        }        while(true) {            len = process.readLine(buffer, maxSize);            qDebug()<<"buffer len"<<len;            /*             * 因為每一行至少還有斷行符號分行符號，因此讀到0，說明waitForReadyRead逾時返回false             */            if(len <= 0) {                break;            }            QString str = QString::fromLocal8Bit(buffer);            qDebug()<<"qstring len"<<str.length();            qDebug()<<str;            qDebug()<<"";        }    }    process.write("exit\r\n");    ret = process.waitForFinished();    qDebug()<<"waitForFinished"<<ret;    process.close();    qDebug()<<"";    qDebug()<<"======================";}

與進程互動

void openProcessThenWrite() {    qDebug()<<"openProcessThenWrite";    qDebug()<<"----------------------";    bool ret;    QProcess *process = new QProcess(QThread::currentThread());    /*     * 如果沒有QCoreApplication的話，會報如下錯誤     * QObject::startTimer: Timers can only be used with threads started with QThread. timer只能在同一個線程中建立和啟動.     */    process->start("cmd", QIODevice::ReadWrite);    ret = process->waitForStarted();    qDebug()<<"waitForReadyRead"<<ret;    QByteArray byteArray = process->readAllStandardOutput();    QString str = QString::fromLocal8Bit(byteArray);    qDebug()<<str;    //這裡不加換行的話命令發不出去    qint64 len = process->write("ping 127.0.0.1\r\nexit\r\n");    qDebug()<<"write len"<<len;    while(true) {        /*         * 如果進程已經關閉，waitForReadyRead會直接返回false         */        ret = process->waitForReadyRead();        qDebug()<<"waitForReadyRead"<<ret;        if(!ret) {            break;        }        byteArray = process->readAllStandardOutput();        str = QString::fromLocal8Bit(byteArray);        qDebug()<<str;        qDebug()<<"";    }    /*     * 如果沒有關閉cmd的指令，因此該process永遠不會finished，會逾時(30秒)返回false     */    ret = process->waitForFinished();    qDebug()<<"waitForFinished"<<ret;    process->close();    delete process;    qDebug()<<"";    qDebug()<<"======================";}

測試函數

#include <QCoreApplication>#include <QDebug>#include <QProcess>#include <QThread>#include <QDateTime>void readProcessAllOnce(bool processAutoExit) {    ……}void readProcessByLine() {    ……}void openProcessThenWrite() {    ……}int main(int argc, char *argv[]){    QCoreApplication a(argc, argv);    qDebug()<<"======================";    readProcessAllOnce(false);    readProcessAllOnce(true);    readProcessByLine();    openProcessThenWrite();    qDebug()<<"That's all";    return a.exec();}