.net Core 中自定义筛选器

本文主要是介绍.net Core 中自定义筛选器，对大家解决编程问题具有一定的参考价值，需要的程序猿们随着小编来一起学习吧！

异常筛选器：

定义：

using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;

public class MyExceptionFilter : IAsyncExceptionFilter
{
    private readonly ILogger<MyExceptionFilter> logger;
    private readonly IHostEnvironment env;
    public MyExceptionFilter(ILogger<MyExceptionFilter> logger, IHostEnvironment env)
    {
        this.logger = logger;
        this.env = env;
    }
    public Task OnExceptionAsync(ExceptionContext context)
    {
        Exception exception = context.Exception;
        logger.LogError(exception, "UnhandledException occured");
        string message;
        if (env.IsDevelopment())
        {
            message = exception.ToString();
        }
        else
        {
            message = "程序中出现未处理异常";
        }
        ObjectResult result = new ObjectResult(new { code = 500, message = message });
        result.StatusCode = 500;
        context.Result = result;
        context.ExceptionHandled = true;
        return Task.CompletedTask;
    }
}

在program。cs 注册这个筛选器：

builder.Services.Configure<MvcOptions>(options =>
{
    options.Filters.Add<MyExceptionFilter>();
});

普通操作筛选器：

定义：

using Microsoft.AspNetCore.Mvc.Filters;

public class MyActionFilter1 : IAsyncActionFilter
{
    public async Task OnActionExecutionAsync(ActionExecutingContext context, 
        ActionExecutionDelegate next)
    {
        Console.WriteLine("MyActionFilter 1:开始执行");
        ActionExecutedContext r = await next();
        if (r.Exception != null)
        {
            Console.WriteLine("MyActionFilter 1:执行失败");
        }
        else
        {
            Console.WriteLine("MyActionFilter 1:执行成功");
        }
    }
}

自动开启事务，自动提交事务的筛选器

using Microsoft.AspNetCore.Mvc.Controllers;
using Microsoft.AspNetCore.Mvc.Filters;
using System.Reflection;
using System.Transactions;

namespace 自动启用事务的筛选器
{
    public class TransactionScopeFilter : IAsyncActionFilter
    {
        public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
        {
            bool hasNotTransactionalAttribute = false;
            if (context.ActionDescriptor is ControllerActionDescriptor)
            {
                var actionDesc = (ControllerActionDescriptor)context.ActionDescriptor;
                hasNotTransactionalAttribute = actionDesc.MethodInfo
                    .IsDefined(typeof(NotTransactionalAttribute));
            }
            if (hasNotTransactionalAttribute)
            {
                await next();
                return;
            }
            using var txScope =
                    new TransactionScope(TransactionScopeAsyncFlowOption.Enabled);
            var result = await next();
            if (result.Exception == null)
            {
                txScope.Complete();
            }
        }
    }
}

[AttributeUsage(AttributeTargets.Method)]
public class NotTransactionalAttribute : Attribute
{
}

以上示例代码来自杨中科老师：

NETBookMaterials/第七章 at main · yangzhongke/NETBookMaterials · GitHub

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