第三节：使用Log4net和过滤器记录异常信息，返回异常给前端

    public class HeaderResult
    {
        public HeaderResult()
        {
            // ReSharper disable once VirtualMemberCallInConstructor
            IsSucceed = false;
        }
     
        public virtual bool IsSucceed { get; set; }
       
        public virtual string Message { get; set; }
      
        public virtual T Result { get; set; }
       
        public virtual string StatusCode { get; set; }
    }
    

    public class ProjectExceptionFilter : IExceptionFilter
 {
    public void OnException(ExceptionContext context)
    {         
       Exception exception = context.Exception;
        var exceptionType = exception.GetType().ToString();
        if (exceptionType == "ProjectCore.Common.DomainException")
        {
            //用来分类处理业务逻辑
        }
        //获取controller的名称
        var controller = context.RouteData.Values["controller"].ToString();
        //获取Action的名称
        var action = context.RouteData.Values["Action"].ToString();
        var errorPath = controller + "/" + action;
        LogHelper.LogError("web service error:" + errorPath, exception);           
        //返回异常信息给前端
        context.Result = new JsonResult(new HeaderResult<string>
        {
            Message = "错误路径:" + errorPath + ":错误信息" + exception.Message+"",
            IsSucceed = false
        });         
        //异常已处理了
        context.ExceptionHandled = true;          
    }
}
</pre>

    public static class LogHelper
{
    private static ILog _logger;

    static LogHelper()
    {
        ILoggerRepository repository = LogManager.CreateRepository("NETCoreRepository");
        XmlConfigurator.Configure(repository, new FileInfo("log4net.config"));          
        LogHelper._logger = LogManager.GetLogger(repository.Name, "NETCorelog4net");
    }
    public static void LogError(string msg, Exception ex)
    {
        string errorMsg = string.Format("【抛出信息】：{0} <br/>【异常类型】：{1} <br/>【异常信息】：{2} <br/>【堆栈调用】：{3}", new object[] { msg,
        ex.GetType().Name, ex.Message, ex.StackTrace });
        errorMsg = errorMsg.Replace("\r\n", "<br>");
        errorMsg = errorMsg.Replace("位置", "<strong style=\"color:red\">位置</strong>");         
        LogHelper._logger.Error(errorMsg);
    }
    public static void LogInfo(string msg)
    {
        LogHelper._logger.Info((object)msg);
    }
    public static void LogDebug(string msg)
    {
        LogHelper._logger.Debug((object)msg);
    }
}
</pre>

       services.AddMvc(options =>
        {

            options.Filters.Add(typeof(ProjectExceptionFilter));              
            options.Filters.Add(typeof(ModelVerificationFilter));              
        }).
           SetCompatibilityVersion(CompatibilityVersion.Version_2_1).
            AddJsonOptions(options =>
            {
                //忽略循环引用
                options.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
                //不使用驼峰样式的key
                options.SerializerSettings.ContractResolver = new DefaultContractResolver();
                //设置时间格式
                options.SerializerSettings.DateFormatString = "yyyy-MM-dd";
            });
</pre>