Qt 进程 QProcess
【摘要】
定义
The QProcess class is used to start external programs and to communicate with them.
QProces...
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");
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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);
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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);
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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()<<"======================";
}
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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()<<"======================";
}
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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()<<"======================";
}
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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();
}
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文章来源: blog.csdn.net，作者：福州-司马懿，版权归原作者所有，如需转载，请联系作者。
原文链接：blog.csdn.net/chy555chy/article/details/53119551
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