Question

我如何检查是否有申请设置?

i.e. app.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
    <add key ="someKey" value="someValue"/>
  </appSettings>
</configuration>

和在法典中

if (ConfigurationManager.AppSettings.ContainsKey("someKey"))
{
  // Do Something
}else{
  // Do Something Else
}

Answer 1

MSDN: 配置管理员。

if (ConfigurationManager.AppSettings[name] != null)
{
// Now do your magic..
}

或

string s = ConfigurationManager.AppSettings["myKey"];
if (!String.IsNullOrEmpty(s))
{
    // Key exists
}
else
{
    // Key doesn t exist
}

Answer 2

if (ConfigurationManager.AppSettings.Settings.AllKeys.Contains("myKey"))
{
    // Key exists
}
else
{
    // Key doesn t exist
}

Answer 3

通过公用和LINQ安全退还违约值。

public T ReadAppSetting<T>(string searchKey, T defaultValue, StringComparison compare = StringComparison.Ordinal)
{
    if (ConfigurationManager.AppSettings.AllKeys.Any(key => string.Compare(key, searchKey, compare) == 0)) {
        try
        { // see if it can be converted.
            var converter = TypeDescriptor.GetConverter(typeof(T));
            if (converter != null) defaultValue = (T)converter.ConvertFromString(ConfigurationManager.AppSettings.GetValues(searchKey).First());
        }
        catch { } // nothing to do just return the defaultValue
    }
    return defaultValue;
}

用途如下:

string LogFileName = ReadAppSetting("LogFile","LogFile");
double DefaultWidth = ReadAppSetting("Width",1280.0);
double DefaultHeight = ReadAppSetting("Height",1024.0);
Color DefaultColor = ReadAppSetting("Color",Colors.Black);

Answer 4

var isAlaCarte = 
    ConfigurationManager.AppSettings.AllKeys.Contains("IsALaCarte") && 
    bool.Parse(ConfigurationManager.AppSettings.Get("IsALaCarte"));

Answer 5

如果你在座标上看着底部,那么,你就能够把它改写成大体。最好先看一下,在试图获得代表之前是否存在价值。

if (!String.IsNullOrEmpty(ConfigurationManager.AppSettings["myKey"]))
{
    String myKey = ConfigurationManager.AppSettings["myKey"].ToString();
}

或者,正如《刑法》所建议:

if (ConfigurationSettings.AppSettings["myKey"] != null)
{
// Now do your magic..
}

Answer 6

Upper options gives flexible to all manner, if you know key type try parsing them bool.TryParse(ConfigurationManager.AppSettings["myKey"], out myvariable);

Answer 7

我认为,准则表述最好:

   const string MyKey = "myKey"

   if (ConfigurationManager.AppSettings.AllKeys.Any(key => key == MyKey))
          {
              // Key exists
          }

Answer 8

我喜欢 codebender swer,但需要在C++/CLI开展工作。这是我结束的。没有准则的使用,而是工作。

generic <typename T> T MyClass::ReadAppSetting(String^ searchKey, T defaultValue) {
  for each (String^ setting in ConfigurationManager::AppSettings->AllKeys) {
    if (setting->Equals(searchKey)) { //  if the key is in the app.config
      try {                           // see if it can be converted
        auto converter = TypeDescriptor::GetConverter((Type^)(T::typeid)); 
        if (converter != nullptr) { return (T)converter->ConvertFromString(ConfigurationManager::AppSettings[searchKey]); }
      } catch (Exception^ ex) {} // nothing to do
    }
  }
  return defaultValue;
}

Answer 9

借助新的C# syntax和TryParse为我做了很好的工作:

  // TimeOut
  if (int.TryParse(ConfigurationManager.AppSettings["timeOut"], out int timeOut))
  {
     this.timeOut = timeOut;
  }

友情链接