在qt环境中，写出完整libusb 异步传输例程，使用多线程读写操作，使用c++实现，封装成一个类

在Qt环境下，使用libusb库进行异步传输并利用多线程处理读写操作，首先需要确保已经安装了Qt和libusb库。以下是一个简单的示例，展示如何创建一个名为`UsbAsyncTransfer`的类，该类负责异步读写操作，并通过Qt的QThread实现多线程：

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

class UsbAsyncTransfer : public QObject
{
    Q_OBJECT

public:
    explicit UsbAsyncTransfer(QIODevice* device, const libusb_device_handle& handle);
    ~UsbAsyncTransfer();

    void startRead(int length, QByteArray* data);
    void startWrite(const QByteArray& data);

signals:
    void readCompleted(int bytesRead);
    void writeCompleted();

private slots:
    void onTransferDone(libusb_transfer* transfer);

private:
    QThread m_thread;
    QIODevice* m_device;
    libusb_device_handle m_deviceHandle;
    libusb_transfer* m_readTransfer;
    libusb_transfer* m_writeTransfer;
};

// 构造函数和析构函数
UsbAsyncTransfer::UsbAsyncTransfer(QIODevice* device, const libusb_device_handle& handle)
{
    // 初始化设备
    m_device = device;
    m_deviceHandle = handle;

    // 创建线程
    moveToThread(&m_thread);
    connect(&m_thread, &QThread::started, this, &UsbAsyncTransfer::startProcessing);
}

UsbAsyncTransfer::~UsbAsyncTransfer()
{
    stop();
    qDeleteAll(transfers());
    deleteLater();
}

// 启动读取操作
void UsbAsyncTransfer::startRead(int length, QByteArray* data)
{
    m_readTransfer = libusb_alloc_transfer(0); // 无缓冲区的读取
    libusb_fill_read(m_readTransfer, m_deviceHandle, 0, static_cast<void*>(data), length, NULL, onTransferDone, this);
    startTransfer(m_readTransfer, "read");
}

// 启动写入操作
void UsbAsyncTransfer::startWrite(const QByteArray& data)
{
    m_writeTransfer = libusb_alloc_transfer(0); // 无缓冲区的写入
    libusb_fill_write(m_writeTransfer, m_deviceHandle, static_cast<void*>(data.data()), data.size(), NULL, onTransferDone, this);
    startTransfer(m_writeTransfer, "write");
}

// 开始传输
void UsbAsyncTransfer::startTransfer(libusb_transfer* transfer, const QString& type)
{
    m_thread.start();
    transfer->callback = this;
    transfer->context = this;
    if (type == "read") {
        libusb_submit_transfer(m_readTransfer);
    } else {
        libusb_submit_transfer(m_writeTransfer);
    }
}

// 传递完成槽函数
void UsbAsyncTransfer::onTransferDone(libusb_transfer* transfer)
{
    int status = libusb_get_error_code(transfer);
    if (status == LIBUSB_SUCCESS) {
        switch (transfer->type) {
            case LIBUSB_TRANSFER_TYPE_BULK:
                emit readCompleted(transfer->actual_length); // 如果是读操作
                break;
            case LIBUSB_TRANSFER_TYPE_IN:
                emit writeCompleted(); // 如果是写操作
                break;
        }

        // 清理并取消未完成的传输
        libusb_free_transfer(transfer);
    } else {
        qDebug() << "Error in USB transfer: " << status;
        stop();
    }
}

// 停止所有传输
void UsbAsyncTransfer::stop()
{
    foreach (libusb_transfer* transfer, transfers()) {
        libusb_cancel_transfer(transfer);
        libusb_free_transfer(transfer);
    }
}

// 所有正在进行的传输
QList<libusb_transfer*> UsbAsyncTransfer::transfers()
{
    return {m_readTransfer, m_writeTransfer};
}

在这个例子中，你需要确保已经包含所需的头文件，并且在main函数或适当的位置实例化这个类。注意这只是一个基础的框架，实际应用可能需要添加错误处理、进度指示和其他功能。