在.NET中向前端发送EventStream流式数据

1.要让Controller类的方法返回EventStream类型的数据，首先需要确保在 Startup.cs 或 Program.cs 文件中注册了 IHttpContextAccessor:

public class Program
{
    public static void Main(string[] args)
    {
        var builder = WebApplication.CreateBuilder(args);

        // 添加服务到容器
        builder.Services.AddHttpContextAccessor();

        // 其他配置...

        var app = builder.Build();

        // 中间件配置...

        app.Run();
    }
}

2.在构造函数或方法注入拿到HttpContext

public class MyController : Controller
{
    public Task TestEventStream([FromServices] IHttpContextAccessor httpContextAccessor,...Args args)
    {
        var httpContext = httpContextAccessor.HttpContext;
        // 使用 httpContext
        
    }
}

3.为上下文设置内容格式为event-stream

// 设置响应格式，设置缓存为关闭
httpContext.Response.ContentType = "text/event-stream";
httpContext.Response.Headers.Add("Cache-Control", "no-cache");
httpContext.Response.Headers.Add("Connection", "keep-alive");

4.使用StreamReader从流数据Stream中读取，并使用Response的Write方法写入Response的响应体当中

public async Task SetResponse(Stream stream,HttpContext context){
    using StreamReader reader = new StreamReader(stream)
    while(!reader.EndOfStream){
        string? line = await reader.ReadLineAsync();
        // 对line进行格式化处理
        string? message = DealWithData(line);
        // 写入到响应体当中
        await context.Response.WriteAsync(message);
        await httpContext.Response.Body.FlushAsync();
    }    
}