经常能在.Net 项目中看到App.Config/Web.Config , 一直没有了解过.Net 自带的对配置文件的读写操作，常规的操作类在 System.Configuration.dll 中 ，比较重要的类为ConfigurationManager

底部有全部代码+单元测试

AppSetting 及 ConnectionString 的读取

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <sectionGroup name="MyGroup" type="AppConfig.MyGroup,Appconfig">
      <section name="MySection" type="AppConfig.MySection,Appconfig" />
    </sectionGroup>
    <section name="MySection" type="AppConfig.MySection,Appconfig" />
  </configSections>
  <appSettings>
    <add key="A" value="a"/>
    <add key="B" value="b"/>
    <add key="C" value="c"/>
  </appSettings>
  <connectionStrings>
    <add connectionString="123" name="1"/>
    <add connectionString="456" name="2"/>
  </connectionStrings>
  <MySection Code="asdas">
    <Member Id="dasd"/>
    <Members>
      <add Id="1"/>
      <add Id="2"/>
      <add Id="3"/>
    </Members>
  </MySection>
  <MyGroup>
    <MySection Code="asdas1">
      <Member Id="dasd1"/>
      <Members>
        <add Id="12"/>
        <add Id="22"/>
      </Members>
    </MySection>
  </MyGroup>
</configuration>

指定AppSetting 的 读取

public string GetAppSettingValue(string appSettingName)
{
    return ConfigurationManager.AppSettings.AllKeys.FirstOrDefault(item => item.Equals(appSettingName)) != null ? ConfigurationManager.AppSettings[appSettingName] : null;
}

指定ConnecString的获取

public string GetConnectString(string name)
{
    return ConfigurationManager.ConnectionStrings[name]?.ConnectionString;
}

自定义内容的读取

• ConfigurationSection
• ConfigurationElement
• ConfigurationSectionGroup
• ConfigurationElementCollection

ConfigurationSection

表示配置文件中的节。

// 自定义一个Section   
internal class MySection : ConfigurationSection
{
    [ConfigurationProperty(nameof(Code))]
    public string Code
    {
        get => base[nameof(Code)].ToString();
    }
}

需要在属性上使用ConfigurationPropertyAttribute

//调用方法      
public string GetMySectionCode()
{
    return (ConfigurationManager.GetSection("MySection") as MySection)?.Code;
}

ConfigurationElement

表示Section的成员

//根据Config 配置属性
public class MyElement : ConfigurationElement
{
    [ConfigurationProperty(nameof(Id))]
    public string Id
    {
        get => this[nameof(Id)].ToString();
    }
}
//同时在MySection 中进行扩展
internal class MySection : ConfigurationSection
{
    ...
    [ConfigurationProperty(nameof(Member))]
    public MyElement Member
    {
        get => base[nameof(Member)] as MyElement;
    }
    ...
}
//调用方法
public string GetMySectionMember()
{
    return (ConfigurationManager.GetSection("MySection") as MySection)?.Member?.Id;
}

ConfigurationElementCollection

表示Element的集合

//定义一个MyElement 的集合    
[ConfigurationCollection(typeof(MyElement))]
internal class MyElementCollection : ConfigurationElementCollection
{
    protected override ConfigurationElement CreateNewElement()
    {
        return new MyElement();
    }

    protected override object GetElementKey(ConfigurationElement element)
    {
        return (element as MyElement).Id;
    }
}
//在Section 中进行填充
internal class MySection : ConfigurationSection
{
    [ConfigurationProperty(nameof(Members)), ConfigurationCollection(typeof(MyElement))]
    public MyElementCollection Members
    {
        get => base[nameof(Members)] as MyElementCollection;
    }
}
//调用
public int GetMySectionMembers()
{
    return (int)(ConfigurationManager.GetSection("MySection") as MySection)?.Members?.Count;
}

ConfigurationSectionGroup

在Section 外面在套一个类

public class MyGroup : ConfigurationSectionGroup
{
    [ConfigurationProperty(nameof(MySection))]
    public MySection MySection { get => this.Sections[nameof(MySection)] as MySection; }
}

// 两种调用方式都可以    
public int GetMySectionMembersInGroup()
{
    return (int)(ConfigurationManager.GetSection("MyGroup/MySection") as MySection)?.Members?.Count;
}
public int GetMySectionMembersInGroupByOpenConfig()
{
    Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);
    var group = (MyGroup)config.GetSectionGroup("MyGroup");
    return group.MySection.Members.Count;
}

处理不是默认名字的Config 文件

ExeConfigurationFileMap exeConfigurationFileMap = new ExeConfigurationFileMap() { ExeConfigFilename = @".\App1.config" };
Configuration config = ConfigurationManager.OpenMappedExeConfiguration(exeConfigurationFileMap,ConfigurationUserLevel.None);

这边加载方式与上面的不同 后续一致

github