配置文件里添加自定义，并能够读取和修改其中的值

Question

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <sectionGroup name="applicationSettings" type="System.Configuration.ApplicationSettingsGroup, System">
      <section name="DevExpress.LookAndFeel.Design.AppSettings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false"/>
    </sectionGroup>

  </configSections>
    <connectionStrings>
        <add name="Main" connectionString="server=170.168.1.2;database=K;uid=sa;pwd=sa@123"/>
        <add name="Detail" connectionString="server=170.168.1.2;database=K;uid=sa;pwd=sa@123"/>
        
    </connectionStrings>
    
    <system.data>
        <DbProviderFactories>
            <add name="SqlClient Data Provider" invariant="System.Data.SqlClient" description=".Net Framework Data Provider for SqlServer" type="System.Data.SqlClient.SqlClientFactory, System.Data"/>
            <add name="MySQL Data Provider" invariant="MySql.Data.MySqlClient" description=".Net Framework Data Provider for MySQL" type="MySql.Data.MySqlClient.MySqlClientFactory, MySql.Data"/>
            <add name="OracleClient Data Provider" invariant="System.Data.OracleClient" description=".Net Framework Data Provider for Oracle" type="System.Data.OracleClient.OracleClientFactory, System.Data.OracleClient, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
            <add name="Oracle Data Provider for .NET" invariant="Oracle.DataAccess.Client" description="Oracle Data Provider for .NET" type="Oracle.DataAccess.Client.OracleClientFactory, Oracle.DataAccess, Version=2.112.1.0, Culture=neutral, PublicKeyToken=89b483f429c47342"/>
            <add name="ODP.NET, Managed Driver" invariant="Oracle.ManagedDataAccess.Client" description="Oracle Data Provider for .NET, Managed Driver" type="Oracle.ManagedDataAccess.Client.OracleClientFactory, Oracle.ManagedDataAccess, Version=4.122.1.0, Culture=neutral, PublicKeyToken=89b483f429c47342"/>
            <add name="OleDb Data Provider" invariant="System.Data.OleDb" description=".Net Framework Data Provider for OleDb" type="System.Data.OleDb.OleDbFactory, System.Data, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089"/>
            <add name="SQLite Data Provider" invariant="System.Data.SQLite" description=".Net Framework Data Provider for SQLite" type="System.Data.SQLite.SQLiteFactory, System.Data.SQLite, Version=1.0.58.0, Culture=neutral, PublicKeyToken=db937bc2d44ff139"/>
        </DbProviderFactories>
    </system.data>
  <applicationSettings>
    <DevExpress.LookAndFeel.Design.AppSettings>
      <setting name="DPIAwarenessMode" serializeAs="String">
        <value>System</value>
      </setting>
      <setting name="RegisterBonusSkins" serializeAs="String">
        <value>True</value>
      </setting>
      <setting name="DefaultAppSkin" serializeAs="String">
        <value>Skin/Office 2019 White</value>
      </setting>
      <setting name="DefaultPalette" serializeAs="String">
        <value></value>
      </setting>
      <setting name="TouchUI" serializeAs="String">
        <value></value>
      </setting>
      <setting name="CompactUI" serializeAs="String">
        <value></value>
      </setting>
      <setting name="TouchScaleFactor" serializeAs="String">
        <value></value>
      </setting>
      <setting name="DirectX" serializeAs="String">
        <value>True</value>
      </setting>
      <setting name="RegisterUserSkins" serializeAs="String">
        <value></value>
      </setting>
      <setting name="FontBehavior" serializeAs="String">
        <value>UseSegoeUI</value>
      </setting>
      <setting name="DefaultAppFont" serializeAs="String">
        <value></value>
      </setting>
      <setting name="CustomPaletteCollection" serializeAs="Xml">
        <value/>
      </setting>
    </DevExpress.LookAndFeel.Design.AppSettings>
  </applicationSettings>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2"/>
  </startup>
</configuration>


想在这个配置文件里添加自定义，并能够读取和修改其中的值，怎样实现呢？

Answer 1

```c#
<appSettings>
  <add key="url" value="www.baidu.com"/>
</appSettings>

获取值：ConfigurationManager.AppSettings["url"]

<connectionStrings>
  <add name="DbConnection" providerName="System.Data.SqlClient" connectionString="server=192.168.0.0;uid=sa;pwd=sa;database=db;pooling=true;max pool size=512;min pool size=0" />
</connectionStrings>

获取值：ConfigurationManager.ConnectionStrings["DbConnection"]

```