从 Spring.NET xml 配置访问 ConfigurationManager.AppSettings 值

我有一个要求，要求我使用 Spring.net 获取存储在 app.config 中的连接字符串，然后将检索到的连接字符串注入到实例化对象中。

我如何使用 Spring.net 的 xml 配置来做到这一点？

例如，我的代码不这样做：

// Spring.net config:
<object name="myService" type="com.acme.MyService, com.acme">
    <constructor-arg type="System.String" value="myConnectionName"/>
</object>

// Web.config:
<connectionStrings>
    <add name="myConnectionName" connectionString="DB_connectionstring"/>
</connectionStrings>

// Codes:
public class MyService {
    public MyService(string connectionName) {
        var connectionString = ConfigurationManager.AppSettings[connectionName];
        // use connectionString to create a DB connection, etc
    }
}

我想要这样的：

 // Spring.net config:
<object name="myService" type="com.acme.MyService, com.acme">
    <constructor-arg type="System.String" ref="retrievedConnectionString"/>
</object>    
// How to make a call similar to "ConfigurationManager.AppSettings[connectionName]" and get the connection string from Web.config and put inside "retrievedConnectionString"?

// Web.config:
<connectionStrings>
    <add name="myConnectionName" connectionString="DB_connectionstring"/>
</connectionStrings>

// Codes:
public class MyService {
    public MyService(string connectionString) {
        // use connectionString to create a DB connection, etc
    }
}

是否可以打电话ConfigurationManager.AppSettings[..]来自 Spring.net xml 配置？

过去我用过一个表达 http://www.springframework.net/doc-latest/reference/html/expressions.html为了实现这一点，但通过这个问题和 bbaia 的回答，我发现更好的方法是使用VariablePlaceholderConfigurer。当您使用VariablePlaceholderConfigurer而不是我的“表达黑客”，你不会把自己束缚在appSettings / connectionStrings变量的样式配置：您可以切换到其中之一VariableSources http://www.springframework.net/doc-latest/reference/html/objects.html#objects-variablesource由 spring.net 提供，甚至实现您自己的IVariableSource.

Spring.NET 提供开箱即用的VariablePlaceholderConfigurer从标准 .NET 设置中检索变量，例如AppSettings, ConnectionStrings, UserSettings and ApplicationSettings。 bbaia 的答案部分说明了这一点，您将在下面找到完整的示例。

“表达式黑客”：调用ConfigurationManager来自 xml 配置

所以，我不建议你使用这个，但这是我过去使用过的技巧，应用于你的配置：

<object object name="myService" type="com.acme.MyService, com.acme">
  <constructor-arg name="Connection" 
                   expression="T(System.Configuration.ConfigurationManager).ConnectionStrings['myConnectionName']" />
</object>

您可以使用相同的方法ConfigurationManager.AppSettings, e.g.:

<object object name="myService" type="com.acme.MyService, com.acme">
  <constructor-arg name="AnotherConstructorArgument" 
                   expression="T(System.Configuration.ConfigurationManager).AppSettings['mySetting']" />
</object>

VariablePlaceholderConfigurer：从 Spring.NET xml 配置引用 .NET 设置

您可以轻松配置VariablePlaceholderConfigurer从标准 .NET 设置中检索变量，例如AppSettings, ConnectionStrings, UserSettings and ApplicationSettings。例如，考虑以下 xml 配置：

<?xml version="1.0" encoding="utf-8"?>
<objects xmlns="http://www.springframework.net" >

  <object type="Spring.Objects.Factory.Config.VariablePlaceholderConfigurer, Spring.Core">
    <property name="VariableSources">
      <list>
        <object type="Spring.Objects.Factory.Config.ConnectionStringsVariableSource, Spring.Core" />
        <object type="Spring.Objects.Factory.Config.ConfigSectionVariableSource, Spring.Core">
          <!-- Sections to read, sepearated by comma (leave out spaces) -->
          <property name="SectionNames"
                    value="appSettings,applicationSettings/q7991262.Properties.Settings,userSettings/q7991262.Properties.Settings" />
        </object>
      </list>
    </property>
  </object>

  <!-- Note that you have to append '.connectionstring' to the key! -->
  <object id="usingConnectionStringsVariableSource" 
          type="q7991262.MyService, q7991262">
    <property name="Connection" 
              value="${myConnectionName.connectionString}" />
  </object>

  <object id="configSectionVariableSource" 
          type="q7991262.MyService, q7991262">
    <property name="Connection" 
              value="${myConnectionNameAppSettings}" />
  </object>

  <object id="userSettingsSection" 
          type="q7991262.MyService, q7991262">
    <property name="Connection" 
              value="${myConectionNameUserSetting}" />
  </object>

  <object id="applicationSetting" 
          type="q7991262.MyService, q7991262">
    <property name="Connection" 
              value="${myConectionNameApplicationSetting}" />
  </object>

</objects>

它从中读取设置app.config:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <configSections>
    <sectionGroup name="userSettings" type="System.Configuration.UserSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
      <section name="q7991262.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" allowExeDefinition="MachineToLocalUser" requirePermission="false" />
    </sectionGroup>
    <sectionGroup name="applicationSettings" type="System.Configuration.ApplicationSettingsGroup, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" >
      <section name="q7991262.Properties.Settings" type="System.Configuration.ClientSettingsSection, System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
    </sectionGroup>
  </configSections>

  <connectionStrings>
    <add name="myConnectionName" 
         connectionString="From connection string section."/>
  </connectionStrings>

  <appSettings>
    <add key="myConnectionNameAppSettings" 
         value="From app setting section." />
  </appSettings>

  <userSettings>
    <q7991262.Properties.Settings>
      <setting name="myConectionNameUserSetting" serializeAs="String">
        <value>My connection from user settings.</value>
      </setting>
    </q7991262.Properties.Settings>
  </userSettings>

  <applicationSettings>
    <q7991262.Properties.Settings>
      <setting name="myConectionNameApplicationSetting" serializeAs="String">
        <value>My connection from application settings.</value>
      </setting>
    </q7991262.Properties.Settings>
  </applicationSettings>

</configuration>

这些配置取自github 上的这个工作示例 https://github.com/serra/stackoverflow/tree/master/spring-questions/q7991262-accessing-configurationmanager.