等待操作符只能在异步方法中使用 [英] The await operator can only be used within an async method

问题描述

我的界面ISFactory如下.

namespace MyApp.ViewModels
{
    public interface IStreamFactory
    {
        Stream CreateSPStream(string sPName);
    }
}

在Windows非通用版本中，上述功能的实现方式如下.

On Windows non-universal version the above function was implemented as follows.

public Stream CreateSerialPortStream(string serialPortName)
{
    var p = new System.IO.Ports.SerialPort();
    p.PortName = serialPortName;
    p.BaudRate = 9600;
    p.RtsEnable = true;
    p.DtrEnable = true;
    p.ReadTimeout = 150;
    p.Open();
    return p.BaseStream;
}

此实现在Windows Universal中不再可用.我的尝试如下所示.

This implementation is no longer available in Windows Universal. What I attempted is shown below.

public  Stream CreateSerialPortStream(string serialPortName)
{
    var selector = SerialDevice.GetDeviceSelector(serialPortName); //Get the serial port on port '3'
    var devices = await DeviceInformation.FindAllAsync(selector);
    if (devices.Any()) //if the device is found
    {
        var deviceInfo = devices.First();
        var serialDevice = await SerialDevice.FromIdAsync(deviceInfo.Id);
        //Set up serial device according to device specifications:
        //This might differ from device to device
        serialDevice.BaudRate = 19600;
        serialDevice.DataBits = 8;
        serialDevice.Parity = SerialParity.None;
    }
}

我收到以下错误消息.

await运算符只能在异步方法中使用.

The await operator can only be used within an async method.`

任何人都可以提出解决方法的建议.

Can anyone suggest a way around this.

推荐答案

最佳方法是使方法async生效，因为编译器错误指示:

The best approach is to make the method async, as the compiler error indicates:

public async Task<Stream> CreateSerialPortStreamAsync(string serialPortName)

这也需要更改界面:

Task<Stream> CreateSerialPortStreamAsync(string serialPortName);

是的，此方法的所有调用方都需要更新.

And yes, all callers of this method will need to be updated.

这篇关于等待操作符只能在异步方法中使用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！