[C++知识库]QProcess简单使用

作用：QProcess类用于启动外部程序，并可以和外部程序进行通信。

继承于QIODevice类，因此可以被视为一个顺序I/O设备。

常用枚举：

ProcessState:NotRunning,Starting,Running.（完整流程Starting->Running->NotRunning）

常用函数：

启动外部程序（当主程序关闭时，外部程序也会关闭）

void start(const QString &program, const QStringList &arguments, QIODevice::OpenMode mode = ReadWrite)
void start(const QString &command, QIODevice::OpenMode mode = ReadWrite)
void start(QIODevice::OpenMode mode = ReadWrite)

?启动外部程序（当主程序关闭时，外部程序不会关闭）

bool startDetached(qint64 *pid = nullptr)

常用信号：

//错误发生
void errorOccurred(QProcess::ProcessError error)

//进程结束
void finished(int exitCode, QProcess::ExitStatus exitStatus)

//进程有错误数据
void readyReadStandardError()

//进程有标准的输出
void readyReadStandardOutput()

//已经开始
void started()

//状态改变
void stateChanged(QProcess::ProcessState newState)

demo代码:

//头文件
#include <QProcess>
#include <QDebug>


//我自定义的按钮槽函数
void QProcessDemo::on_pushButton_clicked()
{
	QProcess *myProcess = new QProcess(this);
	connect(myProcess, &QProcess::started, this, &QProcessDemo::onQProcessStarted);
	connect(myProcess, &QProcess::stateChanged, this,&QProcessDemo::onQProcessStateChanged);
	connect(myProcess, &QProcess::errorOccurred, this, &QProcessDemo::onQProcessErrorOcurred);
	connect(myProcess, QOverload<int, QProcess::ExitStatus>::of(&QProcess::finished),
		[=](int exitCode, QProcess::ExitStatus exitStatus) { 
		qDebug() << exitCode << exitStatus;
	});
	myProcess->start("D://Program Files//Modbus Tools//Modbus Tools//Modbus Poll//mbpoll.exe", QStringList() << "");
}

//下面的是信号对应的槽函数，没有写全
void QProcessDemo::onQProcessStarted()
{
	qDebug() << "QProcess started";
}

void QProcessDemo::onQProcessStateChanged(QProcess::ProcessState newState)
{
	qDebug() << "QProcess current state:" << newState;
}

void QProcessDemo::onQProcessErrorOcurred(QProcess::ProcessError error)
{
	qDebug() << "QProcess errorOcurred:" << error;
}

测试输出：

QProcess current state: QProcess::Starting
QProcess current state: QProcess::Running
QProcess started
QProcess current state: QProcess::NotRunning
0 QProcess::NormalExit