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(); }