Custom Signals and Slots
Simple implementation of Qt multithreading
Passing variables between threads

engineering structure

Main thread class:

//export_key.h#ifndef EXPORT_KEY_H#define EXPORT_KEY_H#include "main_widget.h"namespace Ui {
class export_key;
}
class texport_work;
class export_key : public QWidget
{
    Q_OBJECTpublic:    explicit export_key(QWidget *parent = 0);
    ~export_key();public slots:    int send_cmd(int *len, uchar *pk);private:
    Ui::export_key *ui;    //工作线程对象指针，在类实现中new对象work_thread
    texport_work *work_thread;
    uchar cmd[1024];
    uchar kek[16];
};#endif // EXPORT_KEY_H12345678910111213141516171819202122232425262728291234567891011121314151617181920212223242526272829

//export_key.cpp#include "export_key.h"#include "ui_export_key.h"#include <QMessageBox>//#define printpkexport_key::export_key(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::export_key)
{
    ui->setupUi(this);    //实例化 工作线程的对象
    **work_thread = new texport_work();**    //连接主线程和工作线程,信号处于工作线程，槽位于当前主线程，注意保持信号和槽的参数一致！
    //connect的第五个参数必须为阻塞队列连接，这样才能保证信号传递过来的参数和槽接收的是实时的！
    **connect(work_thread,SIGNAL(send_export_signal(int *,uchar *)),this,SLOT(send_cmd(int *,uchar*)),Qt::BlockingQueuedConnection);**

}//槽的实现int export_key::send_cmd(int *len,uchar* pk)
{
    work_thread->stop();  
    //接收来自工作线程信号传递过来的参数
    mymemcpy(cmd,pk,*len);#ifdef printpk
    int n = 0;    uchar cmd2[2048] = {0};
    n = hextostr(cmd,*len,cmd2);
    cmd2[n] = '\0';
    qDebug("send pk:%s \n",cmd2);#endif

    ui->pbenter->setEnabled(true);    return ErrCode_NoErr;

}
export_key::~export_key()
{
    delete ui;
}1234567891011121314151617181920212223242526272829303132333435363738394041424344454612345678910111213141516171819202122232425262728293031323334353637383940414243444546

Worker class:

#ifndef EXPORT_WORK_H#define EXPORT_WORK_H#include <QThread>#include "main_widget.h"//继承Qthread基类，重写虚函数runclass texport_work : public QThread
{
    Q_OBJECTpublic:     texport_work();protected:     void run();//自定义信号**signals:    void send_export_signal(int *,uchar *);**private:     volatile int start_export;    
};#endif // EXPORT_WORK_H12345678910111213141516171819202122232425261234567891011121314151617181920212223242526

//export_work.cpp#include "export_work.h"#include "export_key.h"#include <QThread>texport_work::texport_work()
{
    start_export = 0;

}//重写虚函数run，在虚函数中实现要在工作线程中要做的事情，开启事件循环void texport_work::run()
{    while(!start_export)
    {
        qDebug()<<"start thread!";
        timerThread();//自定义函数
    }

    start_export = 0;


}void texport_work::stop()
{
    start_export = 1;

}void texport_work::timerThread()
{    int len = 0;    uchar buf[1024];

    len = serial::GetSerialPtr()->recvcommdata(buf);

    if(len <= 0) return;
    if(buf[0] == 0xAA)
    {
        if(buf[1] || buf[2] || buf[3] || buf[4] != 16) return;        //发射信号，自定义信号send_export_signal并将变量len和数组buf传递给槽函数。
        emit send_export_signal(&len,buf);
    }

}12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849501234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950

Summarize:

1. Pay attention to the connection method when connecting signals and slots across threads, that is, the fifth parameter of the connect function
2. To achieve multi-threading, the worker thread inherits the Qthread base class and rewrites the virtual function run to implement what the worker thread needs to do in run ;Create an instance of the worker thread in the main thread to control the worker thread.
3. One way to transfer variables between multiple threads is directly through the connection between the signal and the slot, pay attention to the connection method

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Qt multi-threaded instance

engineering structure

Summarize:

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