自定义中间件（MiddleWare）

原文链接： https://www.cnblogs.com/ysmc/p/16512669.html

　　以下代码自定义简单的异常处理中间件Demo

ExceptionMiddleWare

public class ExceptionMiddleWare
{
    private readonly RequestDelegate _next;
    public ExceptionMiddleWare(RequestDelegate next)
    {
        _next = next;
    }
    public async Task Invoke(HttpContext context)
    {
        try
        {
            await _next.Invoke(context);
        }
        catch (Exception ex)
        {
            await HandleExceptionAsync(context, ex);
        }
    }
    private async Task HandleExceptionAsync(HttpContext context, Exception exception)
    {
        var time = DateTime.Now.ToString("yyyyMMddhhmmss");
        FileHelper.WriteInformationFile(exception.ToString(), Path.Combine("Errlog", DateTime.Now.ToString("yyyyMMdd"), time + ".txt"));
        var response = context.Response;
        response.ContentType = "application/json";
        response.StatusCode = (int)HttpStatusCode.InternalServerError;
        await response.WriteAsync(JsonConvert.SerializeObject(new
        {
            // customize as you need
            error = new
            {
                message = "系统错误，请联系管理员",
                errfile = time
            }
        }));
    }
}

ExceptionMiddleWareBuilder

public static class ExceptionMiddleWareBuilder
{
    public static IApplicationBuilder ExceptionMiddleWare(this IApplicationBuilder builder) => builder.UseMiddleware<ExceptionMiddleWare>();
}

Startup

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    app.HttpRequestMiddleWare();

    if (env.IsDevelopment())
    {
        //app.UseDeveloperExceptionPage();
        app.ExceptionMiddleWare();
    }
    else
        app.ExceptionMiddleWare();

    app.UseMvc();
}