C# 您能否使用匿名委托在控制台应用程序中创建多个观察者？

在另一次提问中，我得到了一个关于使用匿名代表的提示。该功能适用于单个观察者，但当我创建三个观察者时，它只保留最后一个观察者。这是因为匿名委托吗？是否有解决方案

我已经添加了代码

foreach (ConfigurationSectionGroup sectionGroup in sectionGroups)
{
    if (sectionGroup.Name == "FileCheckerConfigGroup")
    {
        foreach(ConfigurationSection configurationSection in sectionGroup.Sections)
        {
            //FileChecker filecheck = new FileChecker();
            //filecheck.ProccessFolders(configurationSection);
            //FileChecker filecheck = new FileChecker();
            var section = ConfigurationManager.GetSection(configurationSection.SectionInformation.SectionName) as NameValueCollection;
            watcher = new FileSystemWatcher(section["inputDirectory"]);
            watcher.EnableRaisingEvents = true;
            watcher.Created += (sender, e) =>
            {
                using (var filecheck = new FileChecker())
                {
                    filecheck.ProccessFolders(configurationSection);
                }
            };                               
        }
    }
}

---

这是因为您使用的是相同的变量

watcher

。尝试在每次迭代中重新创建一个新的观察者：

foreach (ConfigurationSectionGroup sectionGroup in sectionGroups)
{
    if (sectionGroup.Name == "FileCheckerConfigGroup")
    {
        foreach (ConfigurationSection configurationSection in sectionGroup.Sections)
        {
            var section = ConfigurationManager.GetSection(configurationSection.SectionInformation.SectionName) as NameValueCollection;
            var watcher = new FileSystemWatcher(section["inputDirectory"]);
            watcher.EnableRaisingEvents = true;
            watcher.Created += (sender, e) =>
            {
                using (var filecheck = new FileChecker())
                {
                    filecheck.ProccessFolders(configurationSection);
                }
            };                               
        }
    }
}

---

您现在要做的是覆盖以前的观察者。。这就是为什么只有最后定义的观察者才能工作

不知道这是否有效：

watcher = new FileSystemWatcher(section["inputDirectory"]);
 foreach (ConfigurationSectionGroup sectionGroup in sectionGroups)
            {
                if (sectionGroup.Name == "FileCheckerConfigGroup")
                {
                    foreach (ConfigurationSection configurationSection in sectionGroup.Sections)
                    {
                        //FileChecker filecheck = new FileChecker();
                        //filecheck.ProccessFolders(configurationSection);
                        //FileChecker filecheck = new FileChecker();
                        var section = ConfigurationManager.GetSection(configurationSection.SectionInformation.SectionName) as NameValueCollection;
                        watcher.EnableRaisingEvents = true;
                        watcher.Created += (sender, e) =>
                        {
                            using (var filecheck = new FileChecker())
                            {
                                filecheck.ProccessFolders(configurationSection);
                            }
                        };                               
                    }
                }
            }

---

我认为问题在于，在lambda中需要foreach循环之外的元素。在循环中创建它的本地副本，一切都应该正常工作：

foreach (ConfigurationSectionGroup sectionGroup in sectionGroups)
{
    if (sectionGroup.Name == "FileCheckerConfigGroup")
    {
        foreach(ConfigurationSection configurationSection in sectionGroup.Sections)
        {
            //FileChecker filecheck = new FileChecker();
            //filecheck.ProccessFolders(configurationSection);
            //FileChecker filecheck = new FileChecker();
            var localConfigurationSectionCopy = configurationSection;
            var section = ConfigurationManager.GetSection(configurationSection.SectionInformation.SectionName) as NameValueCollection;
            watcher = new FileSystemWatcher(section["inputDirectory"]);
            watcher.EnableRaisingEvents = true;
            watcher.Created += (sender, e) =>
            {
                using (var filecheck = new FileChecker())
                {
                    filecheck.ProccessFolders(localConfigurationSectionCopy);
                }
            };                               
        }
    }
}

---

为了更好地解释问题所在，请看一看。

包含要监视的目录的部分仅在循环中创建，并且对于每个监视者都会有所不同。哦，是的，当然。。您只需要初始化一个新的观察程序，而不是覆盖同一个观察程序。在“FileSystemWatcher=newfilesystemwatcher（第[“inputDirectory”]”部分中更改行“watcher=newfilesystemwatcher（第[“inputDirectory”]”）；这是一个有趣的博客。谢谢你给我指出这一点。