Qt 进程 QProcess

定义

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

QProcess类是用来启动一个外部程序并与之通信。

使用说明

开启外部线程的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().

想要启动一个进程，可以传递你想启动的程序的名字和命令行参数作为参数传递给start()函数。参数作为QStringList中每一个单独的字符串。

或者，你可以通过setProgram()和setArguments()来设置该程序，然后调用start()或者open()启动该程序。

启动时在指定程序名时就附带上参数

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

启动时分别指定函数名和参数列表

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

分别指定函数名和参数，然后再启动

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

一次性读取进程输出

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();    /*     * 如果打开的不是自动关闭的进程，那么这里最多可能会等待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()<<"======================";}

按行读取进程输出

void readProcessByLine() {    qDebug()<<"readProcessByLine";    qDebug()<<"----------------------";    bool ret;    QProcess process(0);    /*     * cmd /c 的命令执行完后会关闭窗口     * cmd /k 的命令执行完后不会关闭窗口     *     * aa && bb 就是执行aa，成功后再执行bb     * aa || bb 先执行aa，若执行成功则不再执行bb，若失败则执行bb     * a  &  b  表示执行a再执行b，而无论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) {        /*         * 一个waitForReadyRead信号可能输出的是多行         */        ret = process.waitForReadyRead();        qDebug()<<"waitForReadyRead"<<ret;        if(!ret) {            break;        }        while(true) {            len = process.readLine(buffer, maxSize);            qDebug()<<"buffer len"<<len;            /*             * 因为每一行至少还有回车换行符，因此读到0，说明waitForReadyRead超时返回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()<<"======================";}

与进程交互

void openProcessThenWrite() {    qDebug()<<"openProcessThenWrite";    qDebug()<<"----------------------";    bool ret;    QProcess *process = new QProcess(QThread::currentThread());    /*     * 如果没有QCoreApplication的话，会报如下错误     * QObject::startTimer: Timers can only be used with threads started with QThread. timer只能在同一个线程中创建和启动.     */    process->start("cmd", QIODevice::ReadWrite);    ret = process->waitForStarted();    qDebug()<<"waitForReadyRead"<<ret;    QByteArray byteArray = process->readAllStandardOutput();    QString str = QString::fromLocal8Bit(byteArray);    qDebug()<<str;    //这里不加换行的话命令发不出去    qint64 len = process->write("ping 127.0.0.1\r\nexit\r\n");    qDebug()<<"write len"<<len;    while(true) {        /*         * 如果进程已经关闭，waitForReadyRead会直接返回false         */        ret = process->waitForReadyRead();        qDebug()<<"waitForReadyRead"<<ret;        if(!ret) {            break;        }        byteArray = process->readAllStandardOutput();        str = QString::fromLocal8Bit(byteArray);        qDebug()<<str;        qDebug()<<"";    }    /*     * 如果没有关闭cmd的指令，因此该process永远不会finished，会超时(30秒)返回false     */    ret = process->waitForFinished();    qDebug()<<"waitForFinished"<<ret;    process->close();    delete process;    qDebug()<<"";    qDebug()<<"======================";}

测试函数

#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();}