asp.net core web mvc之异常

与web api类似，asp.net core web mvc模板也是利用ExceptionHandler来处理错误，在starup的Configure配置数据发生时导向的/home/error

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                app.UseHsts();
            }
            //处理404数据的显示信息
            app.UseStatusCodePages(async context =>
            {
                context.HttpContext.Response.ContentType = "text/plain";
                await context.HttpContext.Response.WriteAsync($"找不到资源，状态码: {context.HttpContext.Response.StatusCode}");
            });
            //……
         }

异常业务类定义如下

using System;
namespace WebError
{
    /// <summary>
    /// 产品异常
    /// </summary>
    public class DaMeiException : ApplicationException
    {
        /// <summary>
        /// 
        /// </summary>
        /// <param name="message"></param>
        public DaMeiException(string message) : base(message)
        {
        }
    }
    /// <summary>
    /// His项目异常
    /// </summary>
    public class HisException : DaMeiException
    {
        /// <summary>
        /// 
        /// </summary>
        /// <param name="message"></param>
        public HisException(string message) : base(message)
        {
        }
    }
    /// <summary>
    /// Lis项目异常
    /// </summary>
    public class LisException : DaMeiException
    {
        /// <summary>
        /// 
        /// </summary>
        /// <param name="message"></param>
        public LisException(string message) : base(message)
        {
        }
    }
    /// <summary>
    /// 模块异常
    /// </summary>
    public class RegisteredException : HisException
    {
        /// <summary>
        /// 
        /// </summary>
        /// <param name="message"></param>
        public RegisteredException(string message) : base(message)
        {
        }
    }
}

Controller.cs中，因为web mvc是有view的，所以把错误返回到ErrorViewModel到View前端进行显示。同样，业务异常类DaMeiException作为错误分类处理的标志，从而完成异常的分类处理。

public IActionResult Privacy()
        {
            var ran = new Random();
            switch (ran.Next(1, 4))
            {
                case 1:
                    int i = 0;
                    var j = 10 / i;
                    return Ok();
                case 2:
                    throw new RegisteredException("这是一个错误");
                default:
                    return View();
            }
        }

        [ResponseCache(Duration = 0, Location = ResponseCacheLocation.None, NoStore = true)]
        public IActionResult Error()
        {
            var context = HttpContext.Features.Get<IExceptionHandlerFeature>();       
            //如果是业务自定义异常，进行特殊处理
            if (context.Error is DaMeiException)
            {
                return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier, ErrorMessage = context.Error.Message, ErrorType = "His" });
            }
            else
            {
                return View(new ErrorViewModel { RequestId = Activity.Current?.Id ?? HttpContext.TraceIdentifier, ErrorMessage = context.Error.Message, ErrorType = "System" });
            }
        }

Error.schtml 完成具体数据的展示  

@model ErrorViewModel
@{
    ViewData["Title"] = "错误";
}
<h1 class="text-danger">错误</h1>
<h2 class="text-danger">一个请求处理错误</h2>
@if (Model.ShowRequestId)
{
    <h3>@Model.ErrorType</h3>
    <p>
        <strong>请求ID:</strong> <code>@Model.RequestId</code>
    </p>
    <p>
        @Model.ErrorMessage
    </p>
}

       每个框都有处理异常的方式，关键是要设计好业务系统中的异常关系，标准化异常处理的流程和格式，方便日志，监控系统采集汇总这些异常，为系统稳定提供保驾护航。

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