.Net Core 同 Asp.Net MVC一样有几种过滤器，这里不再赘述每个过滤器的执行顺序与作用。
在实际项目开发过程中，统一API返回值格式对前端或第三方调用将是非常必要的，在.NetCore中我们可以通过ActionFilterAttribute来进行统一返回值的封装。
在封装之前我们需要考虑下面几个问题：
1，需要对哪些结果进行封装
我目前的做法是，只对ObjectResult进行封装，其他的类型：FileResult,ContentResult,EmptyResult,RedirectResult不予处理
2，对异常错误的封装
既然是统一返回值，当然也要考虑接口异常的问题了
但是不是所有的异常我们都需要返回给前端的，我们可能需要自定义一个业务异常，业务异常可以在前端进行友好提示，系统异常完全没必要抛出给前端或第三方，且需要对系统异常进行日志记录
项目结构：
Exceptions：自定义业务异常
Filters：自定义过滤器（统一结果封装，全局异常）
Models：统一结果实体
部分代码：
using System;
namespace NetCoreCommonResult.Exceptions
{
/// <summary>
/// 自定义业务异常，可以由前端抛出友好的提示
/// </summary>
public class BizException:Exception
{
public BizException()
{
}
public BizException(string message):base(message)
{
}
public BizException(string message, Exception ex) : base(message, ex)
{
}
}
}
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
namespace NetCoreCommonResult.Filters
{
public class CommonResultFilterAttribute : ActionFilterAttribute
{
public override void OnResultExecuting(ResultExecutingContext context)
{
if (context.Result is ObjectResult objRst)
{
if (objRst.Value is Models.ApiResult)
return;
context.Result = new ObjectResult(new Models.ApiResult
{
Success = true,
Message = string.Empty,
Data = objRst.Value
});
}
}
}
}
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using Microsoft.Extensions.Logging;
namespace NetCoreCommonResult.Filters
{
public class GlobalExceptionFilterAttribute : ExceptionFilterAttribute
{
private readonly ILogger<GlobalExceptionFilterAttribute> _logger;
public GlobalExceptionFilterAttribute(ILogger<GlobalExceptionFilterAttribute> logger)
{
_logger = logger;
}
public override void OnException(ExceptionContext context)
{
context.ExceptionHandled = true;
var isBizExp = context.Exception is Exceptions.BizException;
context.Result = new ObjectResult(new Models.ApiResult
{
Success = false,
Message = context.Exception.Message
});
//非业务异常记录errorLog,返回500状态码，前端通过捕获500状态码进行友好提示
if (isBizExp == false)
{
_logger.LogError(context.Exception, context.Exception.Message);
context.HttpContext.Response.StatusCode = 500;
}
base.OnException(context);
}
}
}
Startup.cs
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
namespace NetCoreCommonResult
{
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
services.AddLogging();
services.AddControllers(ops =>
{
//添加过滤器
ops.Filters.Add(new Filters.CommonResultFilterAttribute());
//GlobalExceptionFilterAttribute构造中注入其他服务，需要通过ServiceFilter添加
ops.Filters.Add(new Microsoft.AspNetCore.Mvc.ServiceFilterAttribute(typeof(Filters.GlobalExceptionFilterAttribute)));
});
//注册GlobalExceptionFilterAttribute
services.AddScoped<Filters.GlobalExceptionFilterAttribute>();
}
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
else
{
app.UseExceptionHandler("/Error");
}
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
{
endpoints.MapControllers();
});
}
}
}
最后新建一个Controller然后写上几个不同返回值的的Action
using Microsoft.AspNetCore.Mvc;
using System;
using System.Collections.Generic;
using System.Text;
using System.Threading.Tasks;
namespace NetCoreCommonResult.Controllers
{
[Route("api/[controller]")]
[ApiController]
public class HomeController : ControllerBase
{
/// <summary>
/// string
/// </summary>
/// <returns></returns>
[HttpGet]
public string Index() => "Welecome to .NetCore";
/// <summary>
/// 跳转，不处理
/// </summary>
/// <returns></returns>
[HttpGet("redirect")]
public ActionResult Redirect() => RedirectToAction("Index");
/// <summary>
///
/// </summary>
/// <returns></returns>
[HttpGet("num")]
public int Num() => 10;
/// <summary>
/// 异步
/// </summary>
/// <returns></returns>
[HttpGet("async")]
public Task<IEnumerable<string>> TaskString() =>Task.FromResult<IEnumerable<string>>(new[] { "A","B","C"});
/// <summary>
/// 文件输出，不处理
/// </summary>
/// <returns></returns>
[HttpGet("file")]
public ActionResult GetFile() => File(Encoding.UTF8.GetBytes("File String"), "text/plain");
/// <summary>
/// 空返回值，不处理
/// </summary>
/// <returns></returns>
[HttpGet("empty")]
public ActionResult Empty() => Empty();
/// <summary>
/// contentResult 不处理
/// </summary>
/// <returns></returns>
[HttpGet("content")]
public ActionResult Content() => Content("this is content");
/// <summary>
/// 异常，返回500错误
/// </summary>
/// <returns></returns>
[HttpGet("exception")]
public ActionResult GetException() => throw new InvalidOperationException("invalid");
/// <summary>
/// 自定义异常，返回200
/// </summary>
/// <returns></returns>
[HttpGet("bizException")]
public ActionResult GetBizException() => throw new Exceptions.BizException("bizException");
}
}
下面是返回结果截图：
上图：访问/api/home和/api/home/redirect的结果
上图：Action返回数字的结果
上图：返回string集合的结果
上图：输出文本文件的结果
上图：返回ContentResult的结果
上图：系统异常的结果，输出状态码为500
上图：抛出业务异常的结果，输出状态码200
不知道如何上传ZIP包，实例代码项目已经放到Gitee上了，后面有时间也会写点简单的例子
地址：https://gitee.com/tang3402/net-core-samples.git