c++ - qt 定期检查 QProcess 状态

Question

我从一个文本文件启动多个 QProcesses(例如像 notepad.exe 等不同的程序)并想定期检查它们是否仍在运行。

while 循环不是解决方案，因为它阻塞了 ui 线程。如何实现？在 Java (Android) 中，我会用一个 asynctask 来做到这一点连接到 ScheduldExecutorService。 qt 有类似的东西吗？

这是我开始流程的地方:

void mywidget::startprocesses(QString &text)
{
    QProcess *process = new QProcess(this);
    this->myprocess.append(process);
    process->start(text);
    int state = process->state();
    addlabelstatus(state);
}

这里调用的方法是:

while(!stream->atEnd())                                    //check stream until empty and assign line as a caption to a new QLabel
        {
            this->fileread = stream->readLine();
            if(!this->fileread.isEmpty())
            {
                central->addlabel(this->fileread);
                central->startprocesses(this->fileread);
            }
        }






void mywidget::addlabelstatus(QProcess::ProcessState newstate)
{
    QString sstring;

    if(newstate == 0)
    {
        QString sstring = "Wird nicht ausgeführt";
        QLabel *label = new QLabel(sstring);
        this->processstatus.append(label);
        this->vrarea->addWidget(label);
    }
    else if (newstate == 1)
    {
        QString sstring = "Wird gestartet!";
        QLabel *label = new QLabel(sstring);
        this->processstatus.append(label);
        this->vrarea->addWidget(label);
    }
    else if (newstate == 2)
    {
        QString sstring = "Wird ausgeführt!";
        QLabel *label = new QLabel(sstring);
        this->processstatus.append(label);
        this->vrarea->addWidget(label);
    }
    else
    {
        QString sstring = "kein Status vorhanden!";
        QLabel *label = new QLabel(sstring);
        this->processstatus.append(label);
        this->vrarea->addWidget(label);
    }
}

Answer 1

每个 QProcess 都有 finished(int exitCode, QProcess::ExitStatus exitStatus) 和 stateChanged(QProcess::ProcessState newState) 信号，即当某些进程已终止或更改(按类型)时发出。所以你的代码可以是:

.H 面:

public slots:
    void processFinished(int exitCode, QProcess::ExitStatus exitStatus);
    void addlabelstatus(QProcess::ProcessState newState);

.CPP 端:

void mywidget::processFinished(int exitCode, QProcess::ExitStatus exitStatus)
{
    <...>
}

void mywidget::addlabelstatus(QProcess::ProcessState newState)
{
    switch(newState) {
        <...>
    };
}

// Your code change

QProcess *process = new QProcess(this);
this->myprocess.append(process);
connect(process, &QProcess::finished, this, &mywidget::processFinished);
connect(process, &QProcess::stateChanged, this, &mywidget::addlabelstatus);
process->start(text);

评论问题的更新

你可以这样试试:

.H面

public slots:
    void processFinished(QLabel *label, int exitCode, QProcess::ExitStatus exitStatus);
    void addlabelstatus(QLabel *label, QProcess::ProcessState newState);

.CPP 端

void mywidget::processFinished(QLabel *label, int exitCode, QProcess::ExitStatus exitStatus)
{
    <...>
}

void mywidget::addlabelstatus(QLabel *label, QProcess::ProcessState newState)
{
    switch(newState) {
        <...>
    };
}

while(!stream->atEnd()) {
            this->fileread = stream->readLine();
            if(!this->fileread.isEmpty()) {
                QLabel *label = new QLabel(this->fileread);
                QProcess *process = new QProcess(this);
                this->myprocess.append(process);

                connect(process, &QProcess::finished, [=] 
                (int exitCode, QProcess::ExitStatus exitStatus) 
                { processFinished(label, exitCode, exitStatus); });

                connect(process, &QProcess::stateChanged, [=] 
                (QProcess::ProcessState newState) 
                { addlabelstatus(label, newState); });

                process->start(text);
            }
}