实现自定义配置节处理程序

Question

来自各种来源（包括 stackOverlflow）的收集，但是当我开始使用它时，我收到以下错误消息

“配置属性 'deviceconfig' 可能不是从 ConfigurationSection 派生的。”

我已经在一天的大部分时间里一直在努力解决这个问题，并且还没有更接近解决方案，因此我们将非常感谢您对此事的任何帮助。我是实施自定义配置部分的新手，所以请温柔对待我 :-)

app.config 文件如下所示：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <section name="deviceconfig"  type="CNIMonitor.Core.CustomConfig.DeviceConfig,Core"/>
  </configSections>
<system.diagnostics>
    <sources>
        <!-- This section defines the logging configuration for My.Application.Log -->
        <source name="DefaultSource" switchName="DefaultSwitch">
            <listeners>
                <add name="FileLog"/>
                <!-- Uncomment the below section to write to the Application Event Log -->
                <!--<add name="EventLog"/>-->
            </listeners>
        </source>
    </sources>
    <switches>
        <add name="DefaultSwitch" value="Information" />
    </switches>
    <sharedListeners>
        <add name="FileLog"
             type="Microsoft.VisualBasic.Logging.FileLogTraceListener, Microsoft.VisualBasic, Version=8.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a, processorArchitecture=MSIL" 
             initializeData="FileLogWriter"/>
        <!-- Uncomment the below section and replace APPLICATION_NAME with the name of your application to write to the Application Event Log -->
        <!--<add name="EventLog" type="System.Diagnostics.EventLogTraceListener" initializeData="APPLICATION_NAME"/> -->
    </sharedListeners>
</system.diagnostics>
<deviceconfig>
  <devices>          
      <device deviceid = "1" 
              name = "localhost" 
              ipaddress="127.0.0.1" 
              port="10000"
              status="not listening"
              message="no message"
      />
      <device deviceid ="2" 
              name ="2nd localhost" 
              ipaddress="127.0.0.1" 
              port="20000" 
              status="not listening"
              message="no message"
      />
  </devices>  
</deviceconfig>

Custom Section Handler 代码如下：

Imports System.Configuration

命名空间 CNIMonitor.Core.CustomConfig

Public Class DeviceConfig
    Inherits ConfigurationSection
    <ConfigurationProperty("deviceconfig")> _
    Public ReadOnly Property DeviceConfig() As DeviceConfig
        Get
            Return CType(MyBase.Item("deviceconfig"), DeviceConfig)
        End Get
    End Property
End Class

<ConfigurationCollectionAttribute(GetType(Device))> _
Public Class Devices
    Inherits ConfigurationElementCollection
    Protected Overrides Function CreateNewElement() As ConfigurationElement
        Return New Device
    End Function
    Protected Overrides Function GetElementKey _
    (ByVal element As ConfigurationElement) As Object
        Return CType(element, Device).DeviceID
    End Function
    Public Sub Add(ByVal element As Device)
        Me.BaseAdd(element)
    End Sub
End Class
Public Class Device
    Inherits ConfigurationElement
    <ConfigurationProperty("deviceid", DefaultValue:="", IsKey:=True, IsRequired:=True)> _
    Public Property DeviceID() As String
        Get
            Return CType(MyBase.Item("deviceid"), String)
        End Get
        Set(ByVal value As String)
            MyBase.Item("deviceid") = value
        End Set
    End Property
    <ConfigurationProperty("hostname", DefaultValue:="", IsKey:=True, IsRequired:=False)> _
    Public Property HostName() As String
        Get
            Return CType(MyBase.Item("RegisteredDate"), String)
        End Get
        Set(ByVal value As String)
            MyBase.Item("RegisteredDate") = value
        End Set
    End Property
    <ConfigurationProperty("ipaddress", DefaultValue:="", IsKey:=True, IsRequired:=False)> _
    Public Property IpAddress() As String
        Get
            Return CType(MyBase.Item("ipaddress"), String)
        End Get
        Set(ByVal value As String)
            MyBase.Item("ipaddress") = value
        End Set
    End Property
    <ConfigurationProperty("port", DefaultValue:="", IsKey:=True, IsRequired:=False)> _
    Public Property Port() As String
        Get
            Return CType(MyBase.Item("port"), String)
        End Get
        Set(ByVal value As String)
            MyBase.Item("port") = value
        End Set
    End Property
    <ConfigurationProperty("status", DefaultValue:="", IsKey:=False, IsRequired:=False)> _
    Public Property Status() As String
        Get
            Return CType(MyBase.Item("status"), String)
        End Get
        Set(ByVal value As String)
            MyBase.Item("status") = value
        End Set
    End Property
    <ConfigurationProperty("message", DefaultValue:="", IsKey:=False, IsRequired:=False)> _
    Public Property Message() As String
        Get
            Return CType(MyBase.Item("message"), String)
        End Get
        Set(ByVal value As String)
            MyBase.Item("message") = value
        End Set
    End Property
End Class

End Namespace

Answer 1

顶层不需要 DeviceConfig 属性。您做需要做的是为您的ConfigurationElementCollection 设备添加一个属性。我还会将您的 Devices 类重命名为不那么含糊的名称，例如 DeviceElementCollection。试试这个：

Public Class DeviceConfig    
    Inherits ConfigurationSection    

    <ConfigurationProperty("Devices")> _    
    Public ReadOnly Property Devices() As DeviceElementCollection    
        Get    
            Return CType(Me("Devices"), DeviceElementCollection)    
        End Get    
    End Property    
End Class    

那么，在您对DeviceElementCollection 的定义中，如果不添加以下内容，您可能会遇到问题：

Public Overrides ReadOnly Property CollectionType() As System.Configuration.ConfigurationElementCollectionType
    Get
        Return ConfigurationElementCollectionType.BasicMap
    End Get
End Property

Protected Overrides ReadOnly Property ElementName() As String
    Get
        Return "Device"
    End Get
End Property

我为类似问题写了一个很长的答案（抱歉，用 C#）here。

更新 - 如何在代码中使用

Dim deviceConfiguration as DeviceConfig = ConfigurationManager.GetSection("deviceconfigs")
For Each device As Device in deviceConfiguration.Devices
    '...whatever you need to do
Next