后台任务中的 .Net Core Channel答案

【问题标题】：.Net Core Channel in Background Tasks后台任务中的 .Net Core Channel
【发布时间】：2021-02-14 18:18:50
【问题描述】：

我想在后台服务中使用chanel，但是在运行我的代码时出现这个错误，我需要做什么。

抱歉英语不好

无法解析服务类型 'System.Threading.Channels.ChannelReader`1[SendMailChanel]' 尝试激活“SendEmailService”时

public class SendMailChanel
    {
        public List<SendMail> SendMails { get; set; }
        public List<string> MailTos { get; set; }
    }

public class SendEmailService: BackgroundService
{
      
        private readonly ChannelReader<SendMailChanel> _channel;

        public HostedService(         
            ChannelReader<SendMailChanel> channel)
        {
            _channel = channel;
        }

        protected override async Task ExecuteAsync(CancellationToken cancellationToken)
        {
            await foreach (var item in _channel.ReadAllAsync(cancellationToken))
            {
                try
                {
                    // do your work with data
                }
                catch (Exception e)
                {
                    
                }
            }
        }
}

[ApiController]
[Route("api/data/upload")]
public class UploadController : ControllerBase
{
    private readonly ChannelWriter<SendMailChanel> _channel;

    public UploadController (
        ChannelWriter<SendMailChanel> channel)
    {
        _channel = channel;
    }

    public async Task<IActionResult> Upload([FromForm] FileInfo fileInfo)
    {
        SendMailChanel mailChanel = new SendMailChanel();
        mailChanel.SendMails = lstSendMail;
        mailChanel.MailTos = lstEmailTo;
        await _channel.WriteAsync(mailChanel);

        return Ok();
    }
}

Startup.cs
services.AddHostedService<SendEmailService>();

【问题讨论】：

您尚未在 DI 容器中注册 Channel<SendMail> 的实例
@JohanP 怎么做先生，我谷歌太多但没有找到任何东西这是我尝试过的：1.公共接口 IChannelReader 2.公共 SendEmailService(MySettingsConfiguration 配置，IChannelReader chanel ) 3. services.AddSingleton();但是抛出错误不能将对象...转换为...

标签： c# .net-core channel

【解决方案1】：

按照本指南进行操作

https://flerka.github.io/personal-blog/2020-01-23-communication-with-hosted-service-using-channels/

    services.AddHostedService<SendEmailService>();
    services.AddSingleton<Channel<SendMailChanel>>(Channel.CreateUnbounded<SendMailChanel>(new UnboundedChannelOptions() { SingleReader = true }));
    services.AddSingleton<ChannelReader<SendMailChanel>>(svc => svc.GetRequiredService<Channel<SendMailChanel>>().Reader);
    services.AddSingleton<ChannelWriter<SendMailChanel>>(svc => svc.GetRequiredService<Channel<SendMailChanel>>().Writer);

【讨论】：