在qt环境中，写出完整libusb 同步传输例程，使用多线程读写操作，使用c++实现，封装成一个类，并在主界面调用，显示发送和接收的数据

在Qt环境中，使用libusb库进行同步传输并结合多线程处理读写操作，首先需要安装libusb库并包含相应的头文件。以下是一个基础的例子，我们将创建一个名为`UsbDevice`的类，它包含了读写数据的方法以及多线程处理。请注意，这个例子假设你已经对Qt和libusb有基本了解。

#include <QThread>
#include <QMutex>
#include <QObject>
#include <QPair>
#include <libusb.h>

class UsbDevice : public QObject
{
    Q_OBJECT
public:
    explicit UsbDevice(libusb_device* device, QObject *parent = nullptr);
    ~UsbDevice();

    void sendData(const char* data, int length);
    QByteArray receiveData(int length);

signals:
    void sentDataSignal(const QPair<int, QByteArray>& data);
    void receivedDataSignal(const QPair<int, QByteArray>& data);

private slots:
    void readThreadFunction();
    void writeThreadFunction();

private:
    libusb_device* m_device;
    QMutex m_dataLock;
    QThread* m_readerThread;
    QThread* m_writerThread;

    QByteArray mDataToWrite;
    QByteArray mDataReceived;
};

// 类的构造函数
UsbDevice::UsbDevice(libusb_device* device, QObject *parent) : QObject(parent)
{
    m_device = device;
    // 初始化线程
    m_readerThread = new QThread(this);
    connect(m_readerThread, &QThread::finished, this, &UsbDevice::deleteLater);
    m_writerThread = new QThread(this);
    connect(m_writerThread, &QThread::finished, this, &UsbDevice::deleteLater);
}

// 类的析构函数
~UsbDevice()
{
    if (m_readerThread->isRunning())
        m_readerThread->quit();
    if (m_writerThread->isRunning())
        m_writerThread->quit();
    m_readerThread->wait();
    m_writerThread->wait();
}

// 发送数据
void UsbDevice::sendData(const char* data, int length)
{
    // 将数据复制到内部缓冲区
    QMutexLocker locker(&m_dataLock);
    mDataToWrite.resize(length);
    memcpy(mDataToWrite.data(), data, length);

    // 在新线程中开始写入
    if (!m_writerThread->isRunning()) {
        m_writerThread->start();
        connect(m_writerThread, &QThread::started, [this]() { sendDataTask(); });
    }
}

// 读取数据任务
void UsbDevice::sendDataTask()
{
    Q_ASSERT(!m_writerThread->isFinished());
    Q_ASSERT(!m_readerThread->isRunning());

    libusb_transfer* transfer = libusb_alloc_transfer(0);
    libusb_fill_bulk_transfer(transfer,
                              m_device,
                              LIBUSB_ENDPOINT_IN,
                              (unsigned char*)mDataReceived.data(),
                              mDataToWrite.size(),
                              NULL, // callback function
                              0,     // flags
                              1000); // timeout in milliseconds

    int result;
    while ((result = libusb_submit_transfer(transfer)) != LIBUSB_TRANSFER_COMPLETED) {
        // handle errors and timeouts
    }

    // 线程结束时发出信号
    emit sentDataSignal({transfer->actual_length, QByteArray(mDataReceived.data(), transfer->actual_length)});
}

// 接收数据
QByteArray UsbDevice::receiveData(int length)
{
    QByteArray buffer(length);
    libusb_transfer* transfer = libusb_alloc_transfer(0);
    libusb_fill_bulk_transfer(transfer,
                              m_device,
                              LIBUSB_ENDPOINT_OUT,
                              buffer.data(),
                              length,
                              NULL, // callback function
                              0,     // flags
                              1000); // timeout in milliseconds

    int result;
    while ((result = libusb_submit_transfer(transfer)) != LIBUSB_TRANSFER_COMPLETED) {
        // handle errors and timeouts
    }

    return buffer;
}

// 开始读取线程
void UsbDevice::readThreadFunction()
{
    while (true) {
        // 读取数据，然后在锁保护下更新
        QByteArray newData = receiveData(1024); // 每次读取1KB
        QMutexLocker locker(&m_dataLock);
        mDataReceived.append(newData);

        // 发出接收到数据的信号
        emit receivedDataSignal({newData.size(), newData});
        QThread::sleep(1); // 避免过于频繁地读取
    }
}

// 开始写入线程
void UsbDevice::writeThreadFunction()
{
    sendDataTask();
}

// 主界面调用
// ...

在主界面，你可以这样实例化并调用`UsbDevice`：

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    libusb_context* ctx = libusb_init(nullptr);
    libusb_device_list* devices = libusb_get_device_list(ctx, nullptr);
    libusb_device* device = libusb_get_device_by_index(ctx, 0); // 获取设备

    // 创建UsbDevice实例并启动线程
    UsbDevice* dev = new UsbDevice(device);
    dev->moveToThread(&thread);
    thread.start();

    // 在适当的时候调用sendData和receiveData方法

    delete devices;
    libusb_exit(ctx);
    return app.exec();
}