Python哈希函数啥情况下抛出异常

Posted 2023-05-09

参考技术A 抛出异常是停止运行这个函数中的代码。
哈希算法将一个不定长的输入，通过散列函数变换成一个定长的输出，即散列值。是一种信息摘要算法。对象的hash值比原对象拥有更低的内存复杂度。
它不同于加密。哈希是将目标文本转换成具有相同长度的，不可逆的杂凑字符串，而加密则是将文本转换为具有相同长度的，可逆的密文。哈希算法是不可逆的，只能由输入产生输出，不能由输出产生输入。而加密则是可逆的。即可以从输入产生输出，也可以反过来从输出推出输入。

csharp 一个过滤器（应该用作全局过滤器）来检查应用程序是否配置为脱机，并在此情况下抛出异常

using System;

namespace Utility
{
    public class OfflineException : ApplicationException
    {
        public OACSOfflineException(string message)
            : base(message) 
        {
        }
    }
}

// Apply a filter so that Elmah does not log any "system offline" exceptions. Otherwise the log will 
// be flooded with those messages as users try to access the system while it is down for maintenance.
void ErrorLog_Filtering(object sender, Elmah.ExceptionFilterEventArgs e)
{
    if (e.Exception is OfflineException)
        e.Dismiss();
}

using System;
using System.Net;
using System.Web.Mvc;
using System.Web.Routing;

namespace Web.Filters
{
    /// <summary>
    /// Check whether the application is marked as offline in the config file.
    /// If so, and the user does not have the override permission, throw an exception.
    /// The MVC error handling will deal with displaying the exception message to the user.
    /// </summary>
    public class CheckApplicationOfflineAttribute : ActionFilterAttribute
    {
        public override void OnActionExecuting(ActionExecutingContext filterContext)
        {
            // Only need to carry out the check on parent actions, otherwise there is an unnecessary overhead
            if (filterContext.IsChildAction)
                return;

            if (ConfigurationHelper.ApplicationOffline && !SecurityHelper.UserHasApplicationOfflineOverridePermission)
                throw new OfflineException("The system is offline for maintenance.");
        }
    }
}