我们常常想通过某一个类,来启动一个外部进程
本文将讲解如何通过QProcess来进行启动外部进程
一:了解QProcess
QProcess是Qt框架提供的一个类,用于在应用程序中执行外部进程。它提供了一系列函数来启动、控制和与外部进程进行交互
1.启动进程的方式:
(1.1)分离式:外部程序启动程序后,主程序退出时,被调用的进程继续执行,不退出
[static] bool QProcess::startDetached(const QString &program, const QStringList &arguments, const QString &workingDirectory = QString(), qint64 *pid = nullptr)
(1.2)一体式:当主程序退出时,被主程序调用起来的进程也退出
start还有其他的重载的函数,下面是其中一个
void QProcess::start(const QString &program, const QStringList &arguments, QIODevice::OpenMode mode = ReadWrite)
2:常用的阻塞函数
// 主进程阻塞,直到外部程序启动完毕,
waitForStarted()
// 主进程阻塞,直到外部程序执行完毕
waitForFinished()
3:被调用进程接受数据
QStringList list = QCoreApplication::arguments();
//为什么试3个呢,我明明参数是传的两个 因为第一个参数是我们传的exe启动 全路径 C:\Users\admin\Desktop\a.exe
if (list.size() == 3)
{
QString exeFileName= list.at(0);
QString oneStr = list.at(1);
QString twoStr= list.at(2);
}
4:主进程接受被调用进程的数据
(4.1)使用QFile输出内容被 主进程捕获
QFile file;
file.open(1, QFile::WriteOnly);
file.write("finished");
file.close();
(4.2)使用输出流 被 主进程捕获
cout << "it's message" << endl;
5:常用的信号
//启动完毕
connect(process, &QProcess::started, this, [=]()
{
});
//捕获到消息时
connect(process, &QProcess::readyReadStandardOutput, this, [=]()
{
});
//完成
connect(process, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished), this, [=](int exitCode, QProcess::ExitStatus exitStatus)
{
});
//状态改变
connect(process, &QProcess::stateChanged, this, [=](QProcess::ProcessState state)
{
});
二:使用QPrecess
1:startDetached 启动进程
1:使用了startDetached来启动进程,信号都是无效的,接受不到任何消息
2:当主进程关闭时,被调用的QTcpClientTest.exe 是不会退出的
3:主进程发送的参数,被调用的QTcpClientTest.exe 依然可以接受
void QTcpSeverTest::on_btn1_clicked()
{
QProcess* process = new QProcess(this);
QString str = QApplication::applicationDirPath() + "/QTcpClientTest.exe";
QStringList list;
list.append("123");
list.append("456");
//分离式 启动外部进程
process->startDetached(str, list);
//无效
connect(process, &QProcess::started, this, [=]()
{
qDebug() << "started";
});
//无效
connect(process, &QProcess::readyReadStandardOutput, this, [=]()
{
QString qstr(process->readAllStandardOutput());
qDebug() << "startDetached:" << qstr;
});
connect(process, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished), this, [=](int exitCode, QProcess::ExitStatus exitStatus)
{
QString result = process->readAll();
qDebug() << "result:" << result;
});
//无效
connect(process, &QProcess::stateChanged, this, [=](QProcess::ProcessState state)
{
qDebug() << "show state:";
switch (state)
{
case QProcess::NotRunning:
qDebug() << "Not Running";
break;
case QProcess::Starting:
qDebug() << "Starting";
break;
case QProcess::Running:
qDebug() << "Running";
break;
default:
qDebug() << "otherState";
break;
}
});
}
2:start启动进程
1:使用了startDetached来启动进程,信号都是可以接受的
2:当主进程关闭时,被调用的QTcpClientTest.exe 是随着主进程一起退出
3:主进程发送的参数,被调用的QTcpClientTest.exe 可以接受参数
QProcess* process = new QProcess(this);
QString str = QApplication::applicationDirPath() + "/QTcpClientTest.exe";
QStringList list;
list.append("bbbbb");
list.append("aaaaa");
//启动完毕
connect(process, &QProcess::started, this, [=]()
{
qDebug() << "started:" ;
});
//捕获到消息时
connect(process, &QProcess::readyReadStandardOutput, this, [=]()
{
QString qstr(process->readAllStandardOutput());
qDebug() << "readyReadStandardOutput:" << qstr;
});
//完成
connect(process, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished), this, [=](int exitCode, QProcess::ExitStatus exitStatus)
{
if (exitStatus == QProcess::NormalExit) {
qDebug() << "Process finished with exit code:" << exitCode;
}
else {
qDebug() << "Process crashed!";
}
});
//状态改变
connect(process, &QProcess::stateChanged, this, [=](QProcess::ProcessState state)
{
qDebug() << "show state:";
switch (state)
{
case QProcess::NotRunning:
qDebug() << "Not Running";
break;
case QProcess::Starting:
qDebug() << "Starting";
break;
case QProcess::Running:
qDebug() << "Running";
break;
default:
qDebug() << "otherState";
break;
}
});
//一体式 启动外部进程
process->start(str, list);
3:execute()启动进程
1:使用了execute来启动进程,信号是无效的
2:主进程一直处于阻塞状态,等待被调用的QTcpClientTest.exe完成(关闭软件)
QProcess* process = new QProcess(this);
QString str = QApplication::applicationDirPath() + "/QTcpClientTest.exe";
QStringList list;
list.append("bbbbb");
list.append("aaaaa");
//无效
connect(process, &QProcess::started, this, [=]()
{
qDebug() << "started:";
});
//无效
connect(process, &QProcess::readyReadStandardOutput, this, [=]()
{
QString qstr(process->readAllStandardOutput());
qDebug() << "readyReadStandardOutput:" << qstr;
});
//无效
connect(process, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished), this, [=](int exitCode, QProcess::ExitStatus exitStatus)
{
QString result = process->readAll();
qDebug() << "result:" << result;
});
//无效
connect(process, &QProcess::stateChanged, this, [=](QProcess::ProcessState state)
{
qDebug() << "show state:";
switch (state)
{
case QProcess::NotRunning:
qDebug() << "Not Running";
break;
case QProcess::Starting:
qDebug() << "Starting";
break;
case QProcess::Running:
qDebug() << "Running";
break;
default:
qDebug() << "otherState";
break;
}
});
//如果进程 QTcpClientTest 不关闭 或者完成 , 则此进程一直卡住
int exitCode = QProcess::execute(str, list);
if (exitCode != 0) {
qDebug() << "外部程序执行失败";
}
//接受进程捕获到输出的消息
QByteArray output = process->readAllStandardOutput();
QString msg = QString::fromLocal8Bit(output);
qDebug() << msg;
打印的信息为:QIODevice::read (QProcess): device not open,说明execute没有打开设备,接受不到消息
4:start() + waitForFinished()启动进程
1:使用了execute来启动进程,信号是无效的
2:主进程一直处于阻塞状态,等待被调用的QTcpClientTest.exe完成(关闭软件)
QProcess* process = new QProcess(this);
QString str = QApplication::applicationDirPath() + "/QTcpClientTest.exe";
QStringList list;
list.append("bbbbb");
list.append("aaaaa");
//启动进程
process->start(str,list);
// 等待进程完成
process->waitForFinished();
//接受进程捕获到输出的消息
QByteArray output = process->readAllStandardOutput();
QString msg = QString::fromLocal8Bit(output);
qDebug() << msg;
完整代码:
QProcess完整学习代码文章来源:https://www.toymoban.com/news/detail-650793.html
参考博客:
QProcess使用 一
QProcess使用 二
QProcess使用 三
QProcess使用 四
QProcess使用 五文章来源地址https://www.toymoban.com/news/detail-650793.html
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