将请求的正文作为中间件中的字符串读取

Question

如何在 ASP.NET Core 3.0 中间件中从HttpContext.Request 读取正文值作为字符串？

private static void MyMiddleware(IApplicationBuilder app)
{
    app.Run(async ctx =>
    {
        var body = ctx.Request.??????
        await context.Response.WriteAsync(body);
    });
}

Answer 1

这里有两种自定义中间件的方法，如下所示：

1.第一种方式是在Startup.cs中编写中间件：

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
       //...
        app.Run(async ctx =>
        {
            string body;
            using (var streamReader = new System.IO.StreamReader(ctx.Request.Body, System.Text.Encoding.UTF8))
            {
                body = await streamReader.ReadToEndAsync();
            }
            await ctx.Response.WriteAsync(body);
        });    
       //... 
    }

2.第二种方法是您可以自定义中间件类，如下所示：

public class MyMiddleware
{
    private readonly RequestDelegate _next;

    public MyMiddleware(RequestDelegate next)
    {
        _next = next;
    }
    public async Task Invoke(HttpContext httpContext)
    {
        string body;
        using (var streamReader = new System.IO.StreamReader(httpContext.Request.Body, System.Text.Encoding.UTF8))
        {
            body = await streamReader.ReadToEndAsync();
        }
        await httpContext.Response.WriteAsync(body);
    }
}

然后你需要在Startup.cs中注册：

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        //...
        app.UseMiddleware<MyMiddleware>();
        //...
    }

3.结果：

参考：Write custom ASP.NET Core middleware