<?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？
```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"]
```
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<!-- insert your settings below -->
<appSettings>
<add key="MySetting" value="MySettingValue" />
</appSettings>
<!-- insert your settings above -->
<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>
string MySettingValue=System.Configuration.ConfigurationManager.AppSettings["MySetting"];//“MySettingValue”